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Journal of Animal Science - Article

 

 

This article in

  1. Vol. 85 No. 12, p. 3442-3453
     
    Received: Apr 18, 2007
    Accepted: Aug 20, 2007
    Published: December 8, 2014


    2 Corresponding author(s): joe.crenshaw@amerprotcorp.com
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doi:10.2527/jas.2007-0220

Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried plasma1

  1. J. D. Crenshaw*2,
  2. R. D. Boyd,
  3. J. M. Campbell*,
  4. L. E. Russell*,
  5. R. L. Moser and
  6. M. E. Wilson‡3
  1. APC Inc., Ankeny, IA 50021;
    The Hanor Co. Inc., Franklin, KY 42134; and
    JBS United Inc., Sheridan, IN 46069

Abstract

Four experiments involving 265, 410, 894, and 554 sows (Exp. 1 to 4, respectively) were conducted to determine the effect of spray-dried plasma (SDP) at 0 or 0.25% (Exp. 1 and 2) and 0 or 0.50% (Exp. 3 and 4) in lactation diets on average daily feed disappearance (FD), sum of sow BW, fetal and placental loss from d 110 gestation to weaning (SWL), litter size at weaning, litter weight at weaning, and average days from weaning to first estrus (WEI). Experiments 1, 3, and 4 were conducted during summer months, and Exp. 2 was conducted during fall to winter months. Experiment 1 used only parity 1 and parity 2 sows and Exp. 4 used only mature (>2 parities) sows, whereas Exp. 2 and 3 used all parity groups. Sows fed SDP in Exp. 1 had increased (P < 0.01) FD and a tendency for reduced (P = 0.06) SWL and WEI (P = 0.06). Sows fed SDP in Exp. 2 had a tendency for increased (P = 0.09) sow BW at weaning and reduced (P = 0.09) SWL, whereas other variables were not different between diets. Parity 1 and 2 sows fed SDP in Exp. 3 had increased (P < 0.01) FD, but mature sows fed SDP had reduced (P = 0.02) FD. Pig survival and litter size at weaning for all parity groups was not different between diets. The WEI for parity 1 sows fed SDP was reduced (P = 0.02) and tended to be reduced (P = 0.10) for mature sows fed SDP, but was not different between diets for parity 2 sows. More parity 1 sows fed SDP were detected (P = 0.01) in estrus 4 to 6 d after weaning, and fewer were detected (P < 0.01) in estrus 6 d after weaning compared with control parity 1 sows. In Exp. 4, FD was reduced (P < 0.01) for mature sows fed SDP; however, litter weight and average pig BW at weaning was increased (P < 0.01) with more (P < 0.01) marketable pigs (pig BW > 3.6 kg) weaned per litter. Relatively low dietary levels of SDP (0.25 to 0.50%) fed to parity 1 sows farrowed during summer months increased lactation FD and reduced WEI. Mature sows fed SDP during summer months consumed less lactation feed without compromising WEI, but had an increased litter weight, average pig BW, and number of marketable pigs at weaning.


INTRODUCTION

Attrition of young sows has significant social and economic impacts on achieving sow longevity targets. Reproductive and locomotor problems are 2 major reasons for attrition (Anil et al., 2005). The odds of sow removal before the next farrowing decreased 30% with every 1 kg increase in average daily lactation feed intake (Anil et al., 2006). Reduced lactation feed intake suppressed litter weight gain, increased maternal tissue loss, and increased the probability of a prolonged weaning to estrus interval (WEI) in primiparous sows (Eissen et al., 2003). Conserving protein mass in lactating sows minimized WEI and increased subsequent litter size (Boyd et al., 2000).

Heat stress reduced lactation feed intake, increased maternal BW loss, increased WEI, and reduced subsequent litter size in sows (Spencer et al., 2003). Loss of protein mass (>12%) in heat-stressed lactating sows coincided with impaired follicular development (Clowes et al., 2003). Urogenital diseases (Glock and Bilkei, 2005) and chronic immune system activation (Sauber et al., 1999) adversely affected postpartum sow and litter performance.

Dietary spray-dried plasma (SDP) has proven to have immunological effects on various species. Reduced intestinal inflammation was observed in pigs (Touchette et al., 2002; Bosi et al., 2004; Nofrarías et al., 2006) and rats (Pérez-Bosque et al., 2004) fed SDP. Modulation of the intestinal immune response by SDP may be related to improved mucosal barrier to antigens (Nofrarías et al., 2006; Pérez-Bosque et al., 2006). The outcome of immune modulation by SDP is improved growth and feed intake of young pigs, but this has not been evaluated in periparturient sows. We propose that dietary SDP may enhance lactation feed intake with potential to improve sow and piglet performance. The primary objectives of these experiments were to determine the impact of dietary SDP on lactation feed disappearance, sow and litter performance, and WEI.

MATERIALS AND METHODS

Standard operating procedures for animal care were in accord with published guidelines for animal care (FASS, 1999; National Pork Board, 2004).

This series of experiments are the first to evaluate relatively low and potentially economical levels of SDP in diets for lactating sows farrowed in commercial production conditions. The sows and pigs used in these experiments were located at commercial research farms. All protocols were under the supervision of licensed veterinarians who were certified by the swine welfare assurance program (National Pork Board, 2004). The experimental animals were not subjected to prolonged constraint or surgical procedures.

The SDP used in all experiments was Appetein (APC Inc., Ankeny, IA). Spray-dried plasma was produced from bovine or porcine blood collected at USDA-inspected abattoirs. Blood was collected in a stainless steel container with added anticoagulant. Plasma was separated by centrifugation, chilled to 4°C, and transported to a commercial facility for further processing by ultra-filtration and spray-dried to produce a powder. The powder was transported to a different facility where it was subjected to a chelsination process to produce a granular form of SDP (Appetein, APC Inc.).

Experiments 1 and 2

Objectives for the initial 2 experiments were to determine the effects of 0.25% SDP in lactation diets on sow feed disappearance, sow BW at d 110 of gestation and at weaning, sum of sow BW, fetal and placental loss from d 110 of gestation to weaning, WEI, percentage of sows within WEI category, pigs weaned per litter, and litter weight and average pig BW at weaning.

A total of 265 parity 1 (first litter sows; n = 92) and parity 2 (second litter sows; n = 173) Ausgene sows were used in Exp 1. Sows farrowed the months of August and September at the JBS United research facility (Frankfort, IN). Sows were allotted by parity to dietary lactation treatments containing 0 or 0.25% SDP as they were moved into the farrowing room. The facility had 7 farrowing rooms with thirty 1.5 × 2.1-m crates per room. Rooms and crates were of identical design. Each crate had a nipple drinker accessible for the sow and another accessible for the piglets. Farrowing rooms were thermostatically controlled and mechanically ventilated with air drawn through wet pads to provide evaporative cooling.

Multiparous (parity 1 to parity 10) C22 PIC sows (n = 410) were used in Exp. 2. Sows farrowed at JBS United research facility (Sheridan, IN) from September to December. Sows were randomly allotted by parity to dietary lactation treatments containing 0 or 0.25% SDP as they were moved into the farrowing room. The facility had 5 farrowing rooms with twenty 1.5 × 2.1-m crates per room. Rooms and crates were of identical design. Each crate had a nipple drinker positioned within a bowl, and water was accessible by the sow and the piglets. Farrowing rooms were thermostatically controlled and mechanically ventilated but did not have evaporative cooling provided.

Dietary treatments were offered in meal form and were formulated on an as-fed basis to contain equal amounts of total lysine and ME (Table 1). Sows in both experiments were fed their assigned dietary treatment from the time they entered the farrowing room (4 ± 1 d before farrowing) until weaning at approximately 2 wk of lactation. Sows were given 2.5 kg of feed per day before farrowing and 1.8 kg of feed the day of farrowing; thereafter, sows were given ad libitum access to feed until weaning. Sow feed was delivered 3 times daily to individual sow feeders by a hand scoop filled to full volume, which was 2.5 kg of feed. Technicians were trained before the experiments began to consistently fill the scoops to full volume and to provide adequate amounts of feed between feedings to ensure ad libitum access to feed. Sow feed delivered to individual sows was recorded, but feed wastage from sow feeders was not recorded. Remaining sow feed at weaning or discarded sow feed during lactation was weighed and recorded. Average daily lactation feed was calculated as total lactation feed divided by lactation days from d 1 to weaning. Sow BW was recorded at d 110 of gestation and at weaning. Weaning to estrus interval was recorded on all sows used in Exp. 1 and 2. Sows were assumed anestrous if they were not detected in estrus by d 42 postweaning.

Litter size within 24 h of birth was standardized to 11 ± 1 pigs within farrowing room to provide a similar distribution of pigs per litter across dietary treatments. Litter weights and number of pigs per litter at weaning were recorded. Average pig BW at weaning was calculated as litter weight divided by the number of pigs per litter at weaning. Creep feeding or supplemental milk feeding was not provided during Exp. 1 and 2.

Statistical Analysis.

Experiments 1 and 2 were analyzed as a completely randomized design with a 2 × 2 (Exp. 1) and 2 × 3 (Exp. 2) factorial arrangement of factors (dietary SDP × parity group). Individual sow or litter was the experimental unit. Average parity of sows in Exp. 2 with parity > 2 was not different between diets; therefore, sows were pooled into a parity group described as mature sows. Data analysis was performed for the main effects of diet, parity group (Exp. 1, parity 1 and parity 2; Exp. 2, parity 1, parity 2, and mature), and diet × parity interaction using the percentage difference of least squares means according to PROC MIXED (SAS Inst. Inc., Cary, NC). The main effects of diet, parity, and diet × parity interaction used the residual mean square as the error term. Parity means for Exp. 2 were separated using the LSD test.

An extensive assessment of commercial breeding herd records revealed that parity 1 to 4 sows detected in estrus 4 to 6 d after weaning had the greatest subsequent farrowing rate, most pigs born alive per litter, and oldest parity at time of removal from the herd (Hoshino and Koketsu, 2006). Weaning to estrus interval data of individual sows was placed in categories of estrus by < 4 d, 4 to 6 d, and > 6 d after weaning, or anestrous (yes or no), thus allowing calculation of the percentage of sows within each category. Categorical WEI data analysis was performed for diet, parity, and diet × parity interaction using χ2 analysis and percentage difference of least squares means by using PROC GENMOD of SAS. The main effects of diet, parity, and diet × parity interaction used the residual mean square as the error term. Parity means for Exp. 2 were separated using the LSD test. Least squares means of response variables for the main effects of diet and parity group are reported and considered different if P < 0.05, whereas trends are indicated when P = 0.05 to 0.10.

Experiment 3

Objectives for Exp. 3 were to determine effects of 0.5% SDP in lactation feed on sow feed disappearance, WEI, percentage of sows within WEI category, number of pigs weaned per litter, percentage survival of pigs at weaning, and subsequent farrowing rate and number of pigs born alive per litter.

Experiment 3 was conducted during the months of August to September using a commercial C22 PIC sow herd (The Hanor Company Inc., Ames, OK) utilizing parity segregated management, in which parity 1 sows were housed in 1 quadrant, parity 2 sows at another, and sows having > 2 litters (mature sows) were housed in the remaining quadrants at the sow site. All quadrants were located within 2 km of each other. Each quadrant was managed by a separate group of technicians designated to work only within a quadrant. Each quadrant contained 16 farrowing rooms of identical design with an evaporative cooling pad system for the outer hallways of the rooms. Each room had thermostatically controlled ventilation fans that pulled evaporatively cooled air from the hallways through the room. There were twenty-eight 1.5 × 2.1-m crates per room of identical design fitted with a nipple drinker accessible to the sow and a nipple drinker accessible to the piglets. Four rooms (28 crates per room) were used per quadrant, with 2 lactation cycles (sows farrowed in August and September) completed per room, providing 224 sows per parity 1 and parity 2 quadrants, and 223 sows per mature sow quadrants, for a total of 894 sows in the experiment. Both of the mature sow quadrants had 1 room with 1 empty crate.

One feed bin and automated feed delivery system serviced 2 adjacent farrowing rooms. Dietary treatments were assigned to feed bins. Dietary treatments were fed from entry (2 to 3 d before farrowing) until weaning. Lactation feed was delivered through augers to feed drop dispensers positioned above each farrowing crate. Daily feed delivery to each crate was managed manually by dispensing calibrated amounts of feed to the feeder. Technicians previously trained to manage feed delivery recorded daily feed delivered per sow on individual sow records. Feed delivery for the initial 4 d of lactation for parity 2 and mature sows and the initial 7 d of lactation for parity 1 sows was a controlled amount of feed based on a previously established average ad libitum intake curve for these initial time periods; thereafter, feed was provided ad libitum until weaning. Ad libitum feed delivery occurred 4 times per day at 6-h intervals. Failure of an individual sow to consume 100% of the previous feeding resulted in no further increase for the next 24 h to facilitate complete consumption. Feed wastage from feeders was previously determined to be <5%. Feed remaining in sow feeders at weaning was not recorded.

Lactation feed treatments were pelleted and contained 0 or 0.5% SDP (Table 2). Control parity 1, parity 2, and mature sows were fed diets formulated on an as-fed basis to contain 3.3 Mcal of ME/kg and 1.29, 1.04, and 1.04% total lysine for the respective segregated parity groups. A single diet containing 0.5% SDP was formulated to contain 3.3 Mcal ME/kg and 1.04% total lysine and was fed to all parity groups assigned the SDP treatment. Use of a single diet containing SDP was intentionally done to facilitate feed production and delivery schedules to the parity-segregated quadrants at this site.

Litter size of pigs at birth was not standardized across diets because diets were assigned to rooms; however, cross-fostering of pigs was allowed within 48 h of birth within a room. Creep feed or supplemental milk for pigs was not provided. Pigs were weaned 2 times per week to accommodate production flow to nursery facilities. Pigs per litter after cross-fostering, pigs per litter at weaning, lactation interval, individual sow daily feed delivery, WEI, and pigs born alive in the next litter were recorded.

Weaning to estrus interval data excluded sows that were not moved to breeding facilities, but included sows that were moved to breeding facilities and failed to express estrus. Attrition of parity 1 or parity 2 sows that were not available for breeding was because of mortality before breeding, unintentional culling immediately after weaning due to lameness, parturition difficulty, inadequate milking ability, inadequate body condition, prolapse, gastric ulcer, small litter size at weaning or at birth, or no record of placement into the breeding facility. Attrition of mature sows that were not available for breeding was due to the same reasons as for parity 1 and parity 2 sows, with the exception that some mature sows were intentionally culled due to age.

Statistics Analysis.

Experiment 3 was analyzed as a completely randomized block design separately within segregated parity group (parity 1 sows, parity 2 sows, or mature sows) with individual sow or litter as the experimental unit. Although sows were not randomized to rooms within parity segregated quadrants, distribution of sows from gestation into farrowing rooms was considered a random process because technicians responsible for moving sows to farrowing rooms were unaware of which rooms within a quadrant were designated for the experiment and which feed bins had been assigned dietary treatments. Farrowing room was considered a block to account for potential variation due to room location and management within a quadrant. Parity distribution of mature parity (parity > 2) sows was not recorded; therefore, these sows were described as mature sows. Data analysis was performed for diet and block separately by parity 1 and parity 2 groups and diet, block, and quadrant for mature parity groups using percentage difference of least squares means according to PROC MIXED of SAS. The main effects of diet and block for parity 1 and parity 2 groups and diet, block, and quadrant for mature parity groups used the residual mean square as the error term.

Even though cross-fostering of pigs within 48 h of birth was allowed within a room, litter size was not standardized across diets. Lactation interval also varied across diets because of weaning schedules. Therefore, analysis of lactation performance data included the covariates of lactation interval and pigs per litter after cross-fostering, because both covariates affected (P < 0.05) the remaining response variables within each parity group. Data for average WEI and pigs born alive in the subsequent litter were also analyzed as described for lactation data, but only included data of sows that were moved to breeding facilities.

Weaning to estrus interval data of individual sows was placed in categories of estrus by < 4 d, 4 to 6 d, and > 6 d after weaning, anestrous, or sows having their next litter (yes or no), thus allowing calculation of the percentage of sows within each category. Categorical data analysis was performed for each separate parity group for diet and block (parity 1 and parity 2) and diet, block, and quadrant (mature parity group) using χ2 analysis and percent difference of least squares means by using PROC GENMOD of SAS. The main effects of diet, block, or quadrant (mature parity group) used the residual mean square as the error term. Least squares means of response variables for the main effect of diet within segregated parity group are reported and considered different if P < 0.05, whereas trends are indicated when P = 0.05 to 0.10.

Experiment 4

Objectives for Exp. 4 were to determine effects of 0.5% SDP in lactation diets for mature sows on feed disappearance, number of pigs weaned per litter, number of marketable pigs at weaning (pigs > 3.6 kg of BW or without physical defects), survival of all pigs and marketable pigs at weaning, litter weight at weaning, and average pig BW at weaning.

Experiment 4 involved 554 C22 PIC mature sows farrowed during the month of July at the same site and mature sow quadrants utilized for Exp. 3, but in the subsequent year after Exp. 3 was completed. Sow and diet allotment was the same as described for Exp. 3. Within the 2 mature sow quadrants, there were 10 rooms (28 crates/room; 5 rooms/dietary treatment) utilized in the experiment. Data were collected and analyzed for all sows and litters in rooms assigned the control (n = 10 rooms) or SDP (n = 10 rooms) dietary treatment, with the exception that 5 control sows in 1 room and 1 sow in 1 room fed SDP had been weaned early to accommodate weaning schedules, and these sows and litters were not used in the statistical analyses.

Performance data included lactation interval, daily lactation feed disappearance, pigs per litter after cross-fostering, total pigs weaned per litter, and litter weights at weaning. Litter size of pigs at birth was not standardized across diets because diets were assigned to rooms; however, cross-fostering of pigs was allowed within 48 h of birth within a room. Pigs were weaned 2 times per week as described for Exp. 3. The number of pigs per litter with BW > 3.6 kg at weaning or without physical defects (lameness, ruptures, injuries, poor body condition) or clinical symptoms (dyspnea, diarrhea) was recorded to determine the number of marketable (full value) pigs at weaning. Pigs with BW < 3.6 kg at weaning or with physical defects or clinical symptoms were considered to have no market value. All pigs in a litter were weighed together to record litter weight. Pigs that were obviously less than or greater than 3.6 kg of BW at weaning were not weighed individually; only pigs that were obviously within 3 to 4 kg of BW were weighed within a litter to determine if they were a marketable pig.

Lactation feed treatments were pelleted and contained 0 or 0.5% SDP (Table 2). Dietary treatments were formulated on an as-fed basis to be equivalent in ME (3.3 Mcal/kg) and total lysine (1.0%).

During Exp. 4 an automated supplemental milk system (Soppe Systems Inc., Manchester, IA) was in operation, and all litters within a room had ad libitum access to supplemental milk (Advanced Birthright Nutrition, Marshall, MN) from d 2 to 12 of age. The supplemental milk contained spray-dried animal plasma; however, quantity of supplemental milk delivered per pig was not recorded.

Statistical Analysis.

Experiment 4 was analyzed as a randomized complete block design with individual sow or litter as the experimental unit. Randomization of sows and diets was the same as described for Exp. 3. Farrowing room was considered a block to account for potential variation due to room location and management within a quadrant. Parity of mature sows was recorded (range 3 to 15; mean 5.9 ± 0.1), but was not different (P > 0.60) between diets; therefore, parity effects were not evaluated in subsequent data analysis. Data analysis was performed for diet, block, and quadrant using percent difference of least squares means according to PROC MIXED of SAS. The main effects of diet, block, and quadrant used the residual mean square as the error term. Analysis of data included the covariates of lactation interval and pigs per litter after cross-fostering because of the same reasons described for Exp. 3 and because both covariates affected (P < 0.05) the lactation response variables. Least squares means of response variables for the main effect of diet are reported and considered different if P < 0.05, whereas trends are indicated when P = 0.05 to 0.10.

RESULTS

Experiment 1

No significant diet × parity interactions were detected (P > 0.05) for any of the response variables. Therefore, main effect means for diet and parity of lactation and postweaning responses for AUSGENE sows farrowed during summer months are presented in Table 3. The number of sows per diet and parity was unequal due to randomization; however, average sow parity (1.7 ± 0.06) was not different (P = 0.30) between diets.

Lactation interval (13.9 ± 0.1 d) did not differ (P > 0.10) for diet or parity. Sow BW at d 110 of gestation (P = 0.42) and sow BW at weaning (P = 0.74) was not different for diet; however parity 2 sows had greater BW at d 110 of gestation and at weaning compared with parity 1 sows (P < 0.01). Sows fed 0.25% SDP tended (P = 0.06) to have reduced BW, fetal and placental loss from late pregnancy to weaning compared with control sows. Parity 1 sows had greater (P = 0.04) BW, fetal and placental weight loss compared with parity 2 sows.

Parity 1 sows had less (P < 0.01) feed disappearance than parity 2 sows. Sows fed 0.25% SDP had greater (P < 0.01) feed disappearance compared with control sows. Pigs weaned per litter tended to be more (P = 0.10) for sows fed 0.25% SDP, but parity differences were not detected (P = 0.26). Litter weight was not different (P < 0.10) between diets or parity. Average pig BW at weaning was not different (P = 0.71) between diets, but was less (P < 0.01) for parity 1 sows compared with parity 2 sows.

Average WEI tended to be reduced (P = 0.06) for sows fed 0.25% SDP during lactation and was reduced (P = 0.04) for parity 2 sows compared with parity 1 sows. All sows were detected in estrus postweaning. The percentage of sows detected in estrus by < 4 d, 4 to 6 d, and > 6 d after weaning was not different (P ≥ 0.20) between diets. A greater (P < 0.01) percentage of parity 2 sows were detected in estrus by 4 to 6 d after weaning, and a lower (P < 0.01) percentage of parity 2 sows were detected in estrus > 6 d after weaning compared with parity 1 sows.

Experiment 2

No significant diet × parity interactions were detected (P > 0.25) for any of the response variables. Therefore, main effect means for diet and parity of lactation and postweaning responses for C22 PIC sows farrowed during fall to winter months are presented in Table 4. Number of sows by parity varied due to randomization. Average parity for all sows (3.5 ± 0.2) and mature sows (4.8 ± 0.2) was not different (P > 0.10) between diets.

Lactation interval was not different (P = 0.55) between diets, but differed (P = 0.05) by parity. Lactation interval was less (P < 0.05) for mature sows compared with parity 2 sows. Parity 1 sows had an intermediate (P > 0.05) lactation interval compared with parity 2 and mature sows. Sow BW at d 110 of gestation was not different (P = 0.58) between diets, but differed (P < 0.01) for the main effect of parity with greater (P < 0.05) BW as parity of sows increased. Sow BW at weaning tended to be greater (P = 0.09) and sow BW, fetal and placental loss tended to be reduced (P = 0.09) for sows fed 0.25% SDP compared with control sows. Parity differed (P < 0.01) for sow BW at weaning and sow BW, fetal and placental loss. Sow BW at weaning increased (P < 0.05) as parity age of sows increased, whereas sow BW, fetal and placental weight loss was greater (P < 0.05) for parity 1 and 2 sows compared with mature sows.

Lactation feed disappearance, pigs weaned per litter, litter weight at weaning, and average pig BW at weaning did not differ (P > 0.70) between diets, but parity differences were detected (P < 0.01) for these variables, except for litter weight at weaning (P = 0.24). Lactation feed disappearance was greater (P < 0.05) for mature sows compared with parity 1 and 2 sows. Pigs per litter at weaning were less (P < 0.05) for mature sows compared with parity 1 and parity 2 sows. Average pig BW at weaning was greater (P < 0.05) for mature sows compared with parity 1 sows. Average pig BW at weaning for parity 2 sows was intermediate (P > 0.05) to parity 1 and mature sows.

Average WEI, percentage of sows detected in estrus d 4 to 6 and > 6 d after weaning, and percentage of anestrous sows was not different (P > 0.20) for the main effect of diet. The main effect of parity was different (P < 0.02) for all postweaning response variables. Average WEI was reduced (P < 0.05) for parity 2 and mature sow groups compared with parity 1. The percentage of parity 2 and mature sow groups detected in estrus 4 to 6 d after weaning were greater (P < 0.05) compared with the parity 1 group. The percentage of sows detected in estrus > 6 d after weaning was reduced (P < 0.05) with increasing parity age. Similar percentages of parity 1 and mature sows were anestrous, whereas none of the parity 2 sows were anestrous (P < 0.05).

Experiment 3

Least squares diet means of lactation and postweaning response variables for segregated parity C22 PIC sows fed SDP during summer months are presented in Table 5. Data were analyzed separately by parity groups (parity 1 sows, parity 2 sows, and mature sows). Pigs were cross-fostered by 48 h of age within a room; however, litter size was not standardized across diets, because diets were assigned to rooms. Lactation interval also varied between rooms because of variations in weaning schedules. Both lactation interval and pigs per litter after cross-fostering as covariates had an effect (P < 0.05) on remaining response variables within each parity group; therefore, remaining response variables were adjusted for the covariate of these variables. Lactation interval was greater (P < 0.01) for parity 1 and 2 sows fed 0.5% SDP and less (P < 0.01) for mature sows fed 0.5% SDP compared with their control counterparts. Pigs per litter after cross-fostering were less (P < 0.01) for mature sows fed 0.5% SDP compared with control mature sows.

Lactation feed disappearance was increased (P < 0.01) for parity 1 and parity 2 sows fed 0.5% SDP, whereas mature sows fed 0.5% SDP had reduced (P = 0.02) feed disappearance. Pigs per litter at weaning and pig survival at weaning were not different (P > 0.30) between diets for any of the parity groups.

The number of sows available to breed was less within each parity group because of attrition during lactation or immediately after weaning, or no record of movement to breeding facilities. Intentional culling was done on mature sows due to age in the herd. Reasons for unintentional culling for all parity groups included mortality before breeding, lameness, parturition difficulty, inadequate milking ability, inadequate body condition, prolapse, gastric ulcer, small litter size at weaning or at birth, or no record of placement into the breeding facility. Effects of diet were not different (P > 0.10) for any reasons of sow attrition during lactation or immediately after weaning for any of the parity groups (data not shown).

Average weaning to estrus interval was reduced (P = 0.02) for parity 1 sows fed 0.5% SDP and tended (P = 0.10) to be reduced for mature sows fed 0.5% SDP, but was not different (P = 0.32) between diets for parity 2 sows. Percentage of parity 1 sows detected in estrus < 4 d after weaning tended (P = 0.06) to be increased for sows fed 0.5% SDP and was increased (P = 0.01) for parity 1 sows detected in estrus 4 to 6 d after weaning and fed 0.5% SDP compared with control parity 1 sows. Percentage of parity 1 sows detected in estrus > 6 d after weaning and fed 0.5% SDP was reduced (P < 0.01), whereas percentage of parity 1 sows that were anestrous or had a subsequent litter did not differ (P > 0.80) between diets. Percentages of parity 2 and mature sows within each postweaning category were not different (P> 0.10) between diets. The number of pigs born alive in the subsequent litter was not different (P > 0.20) between diets for any of the parity groups.

Experiment 4

Least squares diet means of lactation response variables for mature C22 PIC sows fed SDP during summer months are presented in Table 6. Average parity (5.85 ± 0.1) of mature sows was not different (P = 0.66) between diets; thus, parity was not included in the statistical model. Pigs were cross-fostered by 48 h of age within a room; however, litter size was not standardized across diets because diets were assigned to rooms. Lactation interval also varied between rooms because of variations in weaning schedules. Both lactation interval and pigs per litter after cross-fostering as covariates had an effect (P < 0.05) on remaining response variables; therefore, remaining response variables were adjusted for the covariate of these variables. Lactation interval was greater (P < 0.01) and pigs per litter after cross-fostering tended (P = 0.06) to be more for sows fed 0.5% SDP.

Lactation feed disappearance was reduced (P < 0.01) for mature sows fed 0.5% SDP. Number of total pigs weaned per litter and percentage survival of all pigs at weaning was not different (P = 0.21) between diets. However, number and percentage survival of marketable pigs at weaning were greater (P < 0.01) for sows fed 0.5% SDP. Marketable pigs included pigs that represented full market value at weaning as determined by lack of physical defects and clinical symptoms or having a BW at weaning > 3.6 kg. Both litter weight and average pig BW at weaning (included all pigs per litter at weaning) were greater (P < 0.01) for sows fed 0.5% SDP.

DISCUSSION

These experiments are the first to evaluate the impact of relatively low dietary levels of SDP in diets for lactating sows. Collectively, the results of these experiments present unique observations on lactation feed consumed by young sows (parity 1 and parity 2) vs. mature sows fed SDP. Lactation feed disappearance of sows farrowed during summer months when heat stress would be anticipated (Exp. 1, 3, and 4) was increased for young sows and decreased for mature sows fed diets containing SDP, whereas feed disappearance of young and mature sows that farrowed during fall and winter months (Exp. 2) was not different between diets. Genetics of sows used in Exp. 1 differed from genetics of sows used in the other experiments; however, feed consumption response to SDP, regardless of dietary SDP level, was similar for sows farrowed during summer months.

The tendency for Ausgene sows in Exp. 1 fed SDP during summer months to have increased sow BW at weaning, reduced sow BW, fetal and placental loss from d 110 of gestation to weaning, increased lactation feed disappearance, and a tendency for reduced WEI is consistent with previous work noting that increased lactation feed intake reduced maternal BW loss and reduced WEI (Boyd et al., 2000; Eissen et al., 2003; Spencer et al., 2003). However, maternal BW loss during lactation was not determined because sow BW after parturition was not recorded; thus, it is difficult to conclude if the increased feed disappearance of the SDP diet had a direct effect on maternal BW loss.

Increased lactation feed disappearance of young sows fed SDP in Exp. 1 is consistent with increased feed intake of weanling pigs fed SDP (Coffey and Cromwell, 2001; Van Dijk et al., 2001). The magnitude of feed intake and growth response to SDP by weanling pigs (Coffey and Cromwell, 1995), broilers (Campbell et al., 2003), and turkeys (Campbell et al., 2004) was greater as antigen exposure increased, even though diets were formulated to contain equal amino acid and caloric content.

Sows in Exp. 1 farrowed during summer months when heat stress would be anticipated. Indicators of heat and antigen stress were not recorded; however, it is generally accepted that lactation feed intake in commercial production is lower during summer months. The reduction of voluntary feed intake by lactating sows housed in heat stress conditions is well documented (Johnston et al., 1999; Renaudeau et al., 2001; Spencer et al., 2003). Heat stress increases body temperature, and initiates disruption of gut barrier resulting in gut leakage and increased serum endotoxin (Lambert, 2004). Chronic immune stimulation reduced average daily lactation feed intake 11% in primiparous sows (Sauber et al., 1999). Parturition stress and urogenital disease also adversely interfere with subsequent sow and litter performance (Glock and Bilkei, 2005).

The increased feed disappearance of lactating sows fed SDP in Exp. 1 may be partially associated with an indirect effect of SDP on immune stress as noted in other animal experiments. Excessive immune stimulation was reduced in antigen challenged pigs (Bosi et al., 2004; Nofrarías et al., 2006) or rats (Pérez-Bosque et al., 2004) fed dietary SDP. Bosi et al. (2004) and Nofrarías et al. (2006) proposed that SDP maintained gut barrier function during an inflammatory event. More recently Pérez-Bosque et al. (2006) determined that SDP fed to antigen challenged rats partially prevented the disruption of mucosal intracellular tight junction proteins thus supporting earlier proposals that SDP maintains gut barrier function.

The tendency for reduced WEI for parity 1 and parity 2 sows fed SDP in Exp. 1 with increased feed disappearance noted for both parity groups is a consistent relationship noted in other studies and implies that attrition due to prolonged WEI of young sows could be reduced if fed SDP during summer months. Reduced lactation feed intake increased the probability of a prolonged WEI in primiparous sows (Eissen et al., 2003). Furthermore, heat stress reduced lactation feed intake, prolonged WEI, and reduced subsequent litter size in sows (Spencer et al., 2003).

Conversely, most response variables of multiparous C22 PIC sows farrowed during fall to winter months in Exp. 2 were not different between dietary SDP levels. Lactation feed disappearance, WEI, and pig performance variables were not different between diets. However, similar to Exp. 1, sow BW, fetal and placental loss from d 110 of gestation to weaning tended to decrease for sows fed SDP. Postweaning response variables were not different between diets. Genetics of sows, experimental sites, and the months sows farrowed were different between Exp. 1 and 2. The differences in response to SDP in these earlier experiments led to further investigations.

Experiment 3 was conducted at a segregated parity commercial herd using the same genetics of sows used in Exp. 2 and the same summer months as used in Exp. 1. Dietary level of SDP was increased from 0.25% in Exp. 1 and 2 to 0.5% in this experiment to potentially magnify the potential response to SDP and because dose response information was lacking. Sow and pig BW variables were not measured during Exp. 3. Post-weaning sow response variables also included the number of pigs born alive in the subsequent litter. Parity segregated sows at this site were fed lactation diets of varying nutrient density. To facilitate feed production and delivery schedules only 1 diet containing 0.5% SDP was fed to all parity groups. The SDP diet was very similar in nutrient density to the parity 2 and mature sow control diet, but contained less total lysine (1.04%) than the control parity 1 diet (1.29%).

As observed in Exp. 1, lactation feed disappearance increased for parity 1 and parity 2 sows in Exp. 3 fed SDP during summer months. Even though total lysine content of the SDP diet was less than the parity 1 control diet, ME content was similar (3.3 Mcal of ME/ kg). The disparity in nutrient content of the parity 1 diets in Exp. 3 may have had some impact on feed disappearance. However, total dietary lysine varying from 0.80 to 1.52% total lysine did not influence feed intake of lactating primiparous sows; only lower levels of total lysine (<0.80%) of lactation diets affected feed intake (Touchette et al., 1998). Nutrient density of the parity 2 control diets and the SDP diet were essentially the same, and parity 2 sows fed SDP also had increased feed disappearance.

The reduction in feed disappearance by mature sows fed SDP in Exp. 3 was not anticipated. Feed disappearance was not affected for mature sows fed 0 vs. 0.25% SDP diets in Exp. 2. Experimental site and months the sows farrowed varied between Exp. 2 and 3. Differences in nutrient density of the control mature sow diet and the SDP diet were minimal.

The relationship of reduced WEI of parity 1 sows in Exp. 3 fed SDP was consistent with increased feed disappearance; however, the relationship of reduced feed disappearance and tendency for reduced WEI of mature sows fed SDP was unique. More parity 1 sows fed the SDP diet were detected in estrus 4 to 6 d after weaning; however, the subsequent farrowing rate and average number of pigs born alive per litter for parity 1 sows were not different between diets. The relationship of more parity 1 sows fed SDP being detected in estrus 4 to 6 d after weaning with a numerical improvement (11.3 vs. 10.4; P = 0.22) of more pig born alive in the subsequent litter was similar to that described by Hoshino and Koketsu (2006).

The novel observation of the reduction in feed disappearance by mature sows fed the 0.5% SDP diet in Exp. 3 led to another experiment. Experiment 4 was conducted the following summer at the same facility used in Exp. 3, but used only mature sows fed iso-nutritive diets containing 0 or 0.5% SDP. As noted in Exp. 3, feed disappearance of mature sows fed 0.5% SDP during summer months in Exp. 4 was reduced; however, litter weight, average pig BW, and number of marketable pigs at weaning were greater for sows fed SDP.

The mechanisms associated with the reduced feed disappearance and greater litter weights of mature sows fed 0.5% SDP in Exp. 4 are unknown. Litter weight and average pig BW at weaning were not different between 0 and 0.25% SDP diets used in Exp. 1 and 2. During Exp. 4 an automated supplemental milk system was in operation that provided supplemental milk replacer to all pigs from d 2 to 12 of age. The amount of supplement milk replacer provided per litter was not measured, nor was milk production of sows measured. Consumption of supplemental milk varies greatly among litters; however, supplemental milk intake was greater for pigs farrowed during summer months when sow feed intake was reduced compared with that of pigs farrowed during cooler months (Azain et al., 1996). Supplemental milk consumption by pigs had no effect on lactation feed intake of sows housed at 25.2°C, but did increase pig BW at weaning (Wolter et al., 2002). The increased pig BW at weaning could have been due to increased consumption of supplemental milk in response to presumably lowered milk production and feed disappearance of sows fed SDP. However, reduction of CP from 17.6 to 14.2% in lactation feed for multiparous sows housed in high ambient temperature did not influence milk production, milk quality, or pig BW gain (Renaudeau et al., 2001). Diets for Exp. 4 were formulated to be iso-nutritive, and the reduced daily feed disappearance of sows fed 0.5% SDP was only about 4% less than control sows.

The improved pig performance response from mature sows fed 0.5% SDP in conjunction with lower feed intake by sows could possibly be related to improvements in the efficiency of nutrient utilization. Blood urea N was reduced in pigs pair-fed a SDP diet with a control diet (Jiang et al., 2000). Glucose transport across intestinal membrane was reduced by immune stimulation; however, immune-stimulated rats fed SDP had 8 to 10% greater glucose uptake (Garriga et al., 2005). The reduced feed disappearance of mature sows fed 0.5% SDP may be related to the ability of SDP to maintain gut barrier function during heat or antigen stress, thus improving nutrient utilization and reducing metabolic demands for more nutrient intake to support increased maintenance and immune response to antigens.

The lack of SDP diet differences in litter weight and average pig BW at weaning in Exp. 1 and 2 could have been related to the dietary level of SDP (0.25 vs. 0.5%), and seasonal heat and antigen stress differences between sites used during the experiments. Additional research is needed to evaluate the feed intake of young and mature sows fed titrated dietary levels of SDP in ambient and heat stress conditions to better understand the unique feed disappearance patterns and litter performance observed in these experiments.

Results of these studies are unique in that young lactating sows fed SDP during summer months had increased feed intake and reduced weaning to estrus interval, whereas mature sows had less feed intake, improved number of marketable pigs at weaning, and heavier litter weights without compromising days to estrus. More research is needed to better understand the effects of SDP on lactating sow and litter performance and the potential impact on subsequent longevity of young sows in a herd.


View Full Table | Close Full ViewTable 1.

Composition of experiment 1 and 2 lactation diets (as-fed basis, %)

 
Ingredient
    Corn 66.75 67.06
    Soybean meal 27.42 26.86
    Dicalcium phosphate 2.36 2.36
    Fish meal 0.99 0.99
    Limestone 0.87 0.87
    Salt 0.49 0.49
    Spray-dried animal plasma 0.00 0.25
    l-Lys 0.15 0.15
    l-Thr 0.03 0.03
    Premix3 0.95 0.95
Calculated composition
    CP, % 19.40 19.35
    ME, Mcal/kg 3.26 3.26
    Calcium, % 1.05 1.04
    Phosphorus, % 0.84 0.84
    Total Lys, % 1.15 1.15

View Full Table | Close Full ViewTable 2.

Composition of experiment 3 and 4 lactation diets (as-fed basis, %)

 
Grain sorghum 35.00 35.81 59.20 35.27 30.00 30.00
Corn 17.04 15.00 15.00 22.15 28.00
Soybean meal 32.10 19.85 19.09 19.60 19.92 19.35
Wheat middlings 7.17 20.00 13.22 20.00 13.79 10.30
Bakery by-product 7.42 5.07
Fat source3 4.40 5.35 4.40 5.70 3.00 3.00
Spray-dried animal plasma 0.50 0.50
Limestone 1.28 1.25 1.27 1.25 1.25 1.26
Monocalcium phosphate 1.25 0.90 0.84 0.90 0.82 0.85
Dynamate4 0.75 0.75 0.75 0.75 0.65 0.65
Salt 0.36 0.35 0.36 0.35 0.25 0.28
Chromax5 0.05 0.05 0.05 0.05 0.10 0.10
Zinc oxide6 0.10 0.10 0.10 0.10
Premix7 0.15 0.15 0.15 0.15 0.19 0.19
Choline-Cl8 0.13 0.13 0.13 0.13 0.17 0.17
l-Lys 0.16 0.23 0.29 0.20 0.20 0.20
l-Thr 0.06 0.07 0.09 0.05 0.07 0.07
dl-Met 0.01 0.04 0.02 0.01
Calculated composition
    CP, % 21.08 17.38 16.96 17.56 17.15 16.94
    ME, Mcal/kg 3.29 3.31 3.29 3.33 3.28 3.29
    Ca, % 0.89 0.78 0.77 0.78 0.77 0.77
    P, % 0.68 0.64 0.59 0.64 0.58 0.57
    Total Lys, % 1.29 1.04 1.04 1.04 1.00 1.00

View Full Table | Close Full ViewTable 3.

Effect of dietary spray-dried animal plasma fed during summer months on sow and litter performance (Exp. 1)1

 
Lactation response4
    No. of sows5 144 121 92 173
    Lactation interval, d 14.0 13.9 0.1 0.39 14.1 13.9 0.1 0.14
    Pregnant sow BW at d 110, kg 214.1 211.9 2.1 0.42 207.8 218.2 2.2 <0.01
    Sow BW at weaning, kg 189.3 190.1 1.8 0.74 182.9 196.6 1.9 <0.01
    Sow BW, fetal and placental loss, kg −24.7 −21.8 1.2 0.06 −24.9 −21.6 1.3 0.04
    Sow feed disappearance, kg/d 4.59 4.89 0.1 <0.01 4.47 5.01 0.1 <0.01
    Pigs per litter at weaning 9.26 9.49 0.1 0.10 9.46 9.29 0.1 0.26
    Litter weight at weaning, kg 46.3 47.7 0.8 0.18 46.2 47.8 0.9 0.13
    Avg. pig BW at weaning, kg 5.00 5.03 0.1 0.71 4.88 5.15 0.1 <0.01
Postweaning response6
    Number of sows detected in estrus 144 121 92 173
    Avg. weaning to estrus interval, d 8.88 7.27 0.6 0.06 8.92 7.23 0.7 0.04
    Sows in estrus < 4 d, % 0.9 0.0 0.6 0.24 0.9 0.0 0.6 0.24
    Sows in estrus 4 to 6 d, % 53.2 61.1 4.7 0.20 45.4 68.9 5.0 <0.01
    Sows in estrus > 6 d, % 45.9 38.9 4.7 0.25 53.7 31.1 5.0 <0.01

View Full Table | Close Full ViewTable 4.

Effect of dietary spray-dried plasma fed during fall and winter months on sow and litter performance (Exp. 2)1

 
Lactation response4
    Number of sows 205 205 95 65 250
    Lactation interval, d 14.1 14.0 0.1 0.55 14.1ab 14.3a 13.8b 0.2 0.05
    Pregnant sow BW at d 110, kg 228.6 230.2 2.1 0.58 207.6a 229.5b 251.1c 3.1 <0.01
    Sow BW at weaning,5 kg 205.7 210.1 2.0 0.09 184.2a 206.1b 233.4c 2.9 <0.01
    Sow BW, fetal and placental loss,5 kg −22.9 −20.2 1.2 0.09 −23.3a −23.4a −18.0b 1.7 <0.01
    Sow feed disappearance, kg/d 6.18 6.18 0.1 0.98 5.88a 6.07a 6.60b 0.1 <0.01
    Pigs per litter at weaning 9.14 9.09 0.1 0.74 9.24a 9.28a 8.84b 0.1 <0.01
    Litter weight at weaning,6 kg 40.0 39.8 0.7 0.80 38.8 40.6 40.2 1.0 0.24
    Avg. pig BW at weaning,6 kg 4.38 4.37 0.1 0.87 4.21a 4.38ab 4.55b 0.1 <0.01
Postweaning response7
    Number of sows detected in estrus 179 181 80 65 215
    Avg. weaning to estrus interval, d 7.24 6.88 0.3 0.42 9.21a 6.26b 5.71b 0.5 <0.01
    Sows in estrus d 4 to 6, % 61.5 66.8 3.7 0.24 37.3a 78.9b 76.2b 5.5 <0.01
    Sows in estrus > d 6, % 28.4 23.5 3.2 0.21 46.9a 21.1b 9.8c 4.6 <0.01
    Anestrous sows, % 10.1 9.8 2.8 0.88 15.8a 0.0b 14.0a 4.0 0.02

View Full Table | Close Full ViewTable 5.

Effect of dietary spray-dried plasma fed during summer months on segregated parity lactating sow and pig performance and postweaning sow performance (Exp. 3)1

 
Lactation response
    Number of sows 112 112 112 112 223 223
    Lactation interval,5 d 17.2 19.9 0.1 <0.01 18.2 19.1 0.2 <0.01 18.7 18.3 0.1 <0.01
    Pigs/litter after cross-fostering 10.7 10.6 0.1 0.19 10.8 10.6 0.1 0.16 11.2 10.8 0.1 <0.01
    Sow feed disappearance,6 kg/d 4.50 5.03 0.1 <0.01 5.30 5.68 0.1 <0.01 5.98 5.79 0.1 0.02
    Pigs/litter at weaning7 9.84 9.94 0.1 0.64 9.56 9.55 0.1 0.94 9.88 9.99 0.1 0.45
    Pig survival at weaning,7 % 92.6 93.7 1.2 0.61 89.5 89.4 1.3 0.96 90.0 91.2 0.9 0.36
Postweaning response8
    Number of sows 94 95 103 101 202 177
    Avg. weaning to estrus interval, d 8.1 5.7 0.6 0.02 5.9 6.6 0.5 0.32 6.4 5.6 0.3 0.10
    Sows in estrus < 4 d, % 0.9 6.1 1.9 0.06 5.8 3.0 2.0 0.32 0.5 0.6 0.5 0.93
    Sows in estrus 4 to 6 d, % 59.1 75.6 4.7 0.01 76.7 78.2 4.2 0.80 84.1 83.7 2.8 0.90
    Sows in estrus > 6 d, % 38.0 16.4 4.5 <0.01 14.6 17.8 3.7 0.52 10.8 10.1 2.3 0.81
    Anestrous sows, % 2.0 1.9 1.5 0.97 2.9 1.0 1.4 0.31 4.6 5.7 1.7 0.59
    Sows having next litter, % 76.8 78.2 4.3 0.82 79.6 87.1 3.7 0.15 85.1 79.6 2.8 0.15
    Pigs born alive/litter 10.4 11.3 0.4 0.22 11.2 11.3 0.4 0.81 10.6 10.6 0.3 0.99

View Full Table | Close Full ViewTable 6.

Effect of dietary spray-dried plasma fed during summer months on lactating mature sow feed disappearance and litter performance (Exp. 4)1

 
Number of sows3 275 279
Average parity of sows 5.88 5.82 0.2 0.66
Lactation interval, d 15.9 16.2 0.1 0.01
Pigs/litter after cross-fostering 10.7 10.9 0.1 0.06
Sow feed disappearance,4 kg/d 5.32 5.11 0.1 <0.01
Pigs/litter at weaning 9.66 9.82 0.1 0.21
Pig survival at weaning, % 90.0 91.4 0.8 0.21
Marketable pigs weaned per litter5 8.94 9.32 0.1 <0.01
Marketable pig survival,5 % 83.4 86.8 0.9 <0.01
Avg. litter weight at weaning, kg 51.1 54.7 0.6 <0.01
Avg. pig BW at weaning, kg 5.28 5.57 0.1 <0.01

 

References

Footnotes


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