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Journal of Animal Science - Animal Production

Effects of supplementation during late gestation on goat performance and behavior under rangeland conditions

 

This article in JAS

  1. Vol. 93 No. 8, p. 4153-4160
     
    Received: Oct 13, 2014
    Accepted: May 27, 2015
    Published: July 24, 2015


    1 Corresponding author(s): velizderas@yahoo.com
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doi:10.2527/jas.2014-8609
  1. J. R. Luna-Orozco*,
  2. C. A. Meza-Herrera,
  3. V. Contreras-Villarreal,
  4. N. Hernández-Macías,
  5. O. Angel-Garcia,
  6. E. Carrillo§,
  7. M. Mellado and
  8. F. G. Véliz-Deras 1
  1. * Centro de Bachillerato Tecnológico Agropecuario No. 1, Torreón, Coahuila, México. 27000
     Universidad Autónoma Chapingo, Unidad Regional Universitaria de Zonas Áridas. Bermejillo, Durango, México. 35230
     Universidad Autónoma Agraria Antonio Narro. Torreón, Coahuila, México. 27054
    § Instituto Tecnológico de Torreón, Torreón, Coahuila, México. 27170

Abstract

This study evaluated the effects of peripartum feed supplementation on doe and kid BW and BCS, milk yield and composition, serum metabolites, and maternal–neonatal behavior under rangeland conditions in northern Mexico. Adult does (n = 23) were randomly assigned to 3 nutritional plane groups: 1) goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum (G15; n = 8), 2) the same supplementation as G15 but from 35 d before until 7 d after kidding (G35; n = 8), and 3) nonsupplemented does (GC; n = 7). Supplemented goats differed from GC goats in BW (48 ± 1.8, 46.1 ± 2.5, and 44.9 ± 2.3 kg; P < 0.05), milk yield (1.8 ± 0.1, 1.9 ± 0.2, and 1.2 ± 0.1 kg at d 15 postpartum; P < 0.01), kid birth weights (3.8 ± 0.2, 3.6 ± 0.2, and 3.4 ± 0.2 kg; P < 0.05), and kid BW at 15 d after birth (6.9 ± 0.2, 6.6 ± 0.2, and 5.6 ± 0.2 kg; P < 0.05) for the G35, G15, and GC, respectively. Serum concentrations for total protein, glucose, and cholesterol were not affected (P > 0.05) by treatments. Milk of GC goats showed increased (P < 0.05) percentages for fat, protein, lactose, and nonfat milk solids, whereas total quantities of these variables where higher (P < 0.05) in the G15 and G35 groups. Furthermore, GC dams spent more time seeking their offspring and emitted more low-pitched bleats 4 h postpartum (P < 0.05) in a 2-choice test compared with the G15 and G35 groups. In general, peripartum supplementation promoted a closer dam–kid relationship at 8 h postpartum. Goat performance may be improved in this semiarid region of Mexico with marginal production through supplementation in late gestation.



INTRODUCTION

Increased kid mortality rate under extensive rangeland conditions has been documented (Slayi et al., 2014; Petros et al., 2014); a greater understanding of maternal behavior may enhance neonate survival for range goats. Dams quickly establish a preferential bond with their offspring and rejects alien kids (Poindron et al., 2007a). Certainly, does recognize the appearance (Kendrick et al., 2001; Poindron et al., 2007a), odor (Lévy et al., 2004; Poindron et al., 2007b), and vocalization of their kids (Briefer et al., 2012). However, any disturbance in either maternal care or mutual recognition may be detrimental to kid survival shortly after birth (Nowak et al., 2007).

One critical issue regarding kid survival is the nutrition of dams during pregnancy. Pregnant goats that are undernourished give birth to kids with a reduced birth weight and heightened mortality rates (Laporte-Broux et al., 2011). Furthermore, undernutrition reduces udder development while decreasing production and quality of both colostrum and milk (Nowak and Poindron, 2006; Celi et al., 2008). Supplemental food during late pregnancy has been shown to reduce kid mortality by improving birth weight and enhancing the immune system while reducing the incidence of hypothermia (Hashemi et al., 2008; Mahboub et al., 2013).

In marginal-rangeland goat production systems, the opportunity to express optimum maternal behavior can be also hindered by the temporary early separation of kids when mothers are taken to the rangeland for grazing during the day. In addition, other factors hindering maternal behavior may include high goat densities in pens at night, greater herd manipulation during kidding periods, and other environment factors such as dams feeding on toxic plants such as locoweed (Oxytropis sericea), which adversely affects maternal nutrition and behavior (Pfister et al., 2006). The aim of this study was to evaluate the effect of supplementation during late gestation on mother–young bonding behavior, milk yield and composition, and serum concentration of some blood metabolites of dams as well as BW dynamics in both does and kids during early lactation.


MATERIAL AND METHODS

General

All procedures and methods used in this study regarding the use and care of animals were carried out in accordance with accepted international (FASS, 2010) and national (NAM, 2002) animal use and care guidelines.

Location, Environmental Conditions, Goat Management, and Treatments

The study was conducted in a rural community of northeast Mexico (26°23′ N, 103°47′ W), approximately 10 km north of Torreon, Mexico. The elevation of the study area is 1,117 m above sea level. The rainy season extends from June to October with mean annual rainfall and temperature of 225 mm and 24°C, respectively. The vegetation type is a highly degraded desert scrub and is characterized as Chihuahuan desert rangeland. Creosotebush [Larrea tridentata (DC.) Coville] dominates the grazing area. Other important species include lechuguilla (Agave lechuguilla Torr.), mesquite (Prosopis glandulosa Torr. var. glandulosa), and blue grama [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths]. The stocking rate is approximately 1.5 ha per goat, which was above the carrying capacity of this rangeland. Total standing crop in this environment is around 2,000 kg DM/ha, with browse providing the bulk of available forage (Mellado et al., 2012a). Goats grazed an open range driven by a herdsman 7 h/d (1100–1800 h), all year round. Animals were penned at night and managed according the traditional procedures used by marginal goat producers in northern Mexico.

Multiparous crossbred goats (n = 23) that were a mixture of dairy and native goats, experienced at grazing on this desert rangeland, were used. Goats were initially selected so they had a similar BCS of 2.5 (1 = emaciated to 4 = obese, in 0.5 increments), as determined by tactile appraisal of fat over the sternum and lumbar vertebrae. Goats were induced into estrus and bred in April using a testosterone-treated buck (Luna-Orozco et al., 2012). Does exposed to bucks were treated with 25 mg progesterone intramuscular to avoid short estrus cycles. The breeding date of each goat was recorded to ascertain the gestation age of these animals.

Thereafter, goats were randomly assigned to 1 of 3 experimental treatment groups: 1) goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum (G15; n = 8), 2) the same supplementation as G15 but from 35 d before until 7 d after kidding (G35; n = 8), and 3) nonsupplemented does (GC; n = 7). The offered concentrate (Table 1) included 20% chicken manure, 37% rolled corn, 37% wheat bran, 4% molasses, and 2% mineral salt; the concentrate was individually feed according to treatment group. Feed supplementation was offered shortly before leaving the pen for grazing. All experimental goats were taken to different grazing sites every day, and animals walked approximately 5 km daily from the rangeland to their pen; grazing constrains can be considered negligible in that goats were taken to different grazing sites every day (Gaytan et al., 2014). Even so, the intake requirements of pregnant goats are well above maintenance and forage availability in this environment, which barely supports gestation (Mellado et al., 2011). Water was available only once a day at a watering point away from the pen. Before parturition, goats were placed indoors and kidded in a roofed dirt-floor pen without bedding.


View Full Table | Close Full ViewTable 1.

Means (±SEM) for doe BW (kg), BCS (units), and milk yield (kg) over time in goats kept under rangeland conditions in northern Mexico

 
Dam BW, kg
Dam BCS,2 units
Milk yield, kg
Treatment1 Initial3 Parturition Initial Parturition 7 d 15 d
GC 54.9 ± 3.2a 44.9 ± 2.3a 2.5 ± 0.1a 1.7 ± 0.2a 1.2 ± 0.2a 1.2 ± 0.1a
G15 54.7 ± 3.6a 46.1 ± 1.5b 2.3 ± 0.2a 1.9 ± 0.2a 1.6 ± 0.2b 1.9 ± 0.2b
G35 55.1 ± 1.6a 48 ± 1.8b 2.3 ± 0.1a 1.9 ± 0.1a 1.6 ± 0.1b 1.8 ± 0.1b
a,bWithin a column, means without a common superscript differ (P < 0.05).
1GC = nonsupplemented does; G15 = goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum; G35 = same supplementation as G15 but from 35 d before until 7 d after kidding.
21 = emaciated and 4 = obese.
330 d prepartum.

Experimental Procedures, Measurements, and Response Variables

Goats were weighed at the beginning of the study and at parturition. Body condition score was also registered 30 d prepartum and at kidding. In addition, blood samples (10 mL) were collected by jugular venipuncture on d –30, –15, 0, +7, and +15 with respect to parturition. Blood samples were allowed to clot at room temperature for 30 min, and serum was separated by centrifugation (1,500 × g for 15 min at 20°C), decanted and collected in duplicate in polypropylene microtubes (Axygen Scientific, Union City, CA), and stored at –20°C until analyses. Glucose was determined with a portable glucose meter (True Read; Laboratory Dai, La Trinidad, Caracas, Venezuela). The biuret test was used to assess the concentration of serum proteins. Color intensity was registered with a Coleman Junior II spectrophotometer at 540 nm (Perkin Elmer, Maywood, IL) to obtain the protein concentration. Blood serum cholesterol concentration was determined with thecholesterol oxidase-phenol + aminophenazone enzymatic colorimetric method (MTI Diagnostics, Ames, IA).

Milk yield was determined on d 7 and 15 postpartum; kids were isolated from their mothers the previous evening (1700 h), and females were hand milked the next morning; under this production system, goats are routinely hand milked without the use of hormonal injection (i.e., oxytocin). Milk was weighed and milk samples were collected and preserved at 4°C until determination of chemical composition. Milk content for protein, fat, lactose, and total solids content was estimated by infrared spectroscopy (MilkoScan; Electric, Hillerod, Denmark). Kid BW was recorded at birth and at d 7 and 15 postpartum.

Evaluation of the behavioral dam–kids interaction at parturition was assessed in the 3 experimental groups using a 2-choice test in which dams could choose between the presence of their own or an alien kid of similar age at 4 h postpartum (Nowak et al., 1987). Dams were tested in a triangular testing enclosure (Fig. 1). All tests were conducted in the goats’ pen in which the animals were permanently kept at night. Each of the 2 stimulus kids—the own and the alien—was placed in 1 of the 2 small holding pens, located opposite the pen where the mother was kept. The test started with the introduction of the dam into its holding pen for 30 s, during which time she could hear the vocalizations of both kids. Then, the doe was released and its behavior recorded during 5 min. The same test was made for the kids using their own and an alien dam in a smaller triangular testing enclosure at 8 h postpartum (Fig. 1). The following variables were recorded: 1) the approaches of the test animal to their offspring or dam, 2) the time spent by the animals seeking the stimulus animal, 3) the vocalization activity of dams and young, 4) preference for their own or an alien kid, and 5) latency to approach, through the “natural zone” to the “contact zone,” considering either alien or own dam/kid after exiting the start box (Nowak et al., 1987).

Figure 1.
Figure 1.

Diagram of the test arena used for the 2-choice test for does (left panel) and kids (right panel). Zone 1: starting pen. Zone 2: neutral zone. Zone 3 and 4: proximity zone. Zone 5 and 6: holding pens for the stimulus animals.

 

Statistical Analyses

The effects of prepartum feed supplementation on blood metabolites, weight gain of kids and dams, and milk yield of dams were analyzed by ANOVA using the MIXED procedure of SAS (version 9.1; SAS Inst. Inc., Cary, NC). Significant differences detected by ANOVA were further investigated using a Tukey’s honest significant difference post hoc test comparing goat groups. Body condition score among treatments was analyzed with a Kruskal–Wallis test. Wilcoxon rank-sum nonparametric tests (NPAR1WAY procedure of SAS) were conducted to compare the proportions of the various types of bleats, approaches to stimulus animals, and the time spent seeking the stimulus animals. Further nonparametric analyses were made to compare behavioral events between the own and the alien kids. All the statistical analyses were computed using the procedures of SAS; the significance level was set at P < 0.05.


RESULTS

Initial BW (d 30 before kidding) did not differ between treatments groups, but BW did differ between treatments at parturition, with both supplement groups showing a higher BW (P < 0.05) compared with the GC group (Table 1). The G35 and G15 groups did not differ (P = 0.5) in BW at parturition. Litter size did not differ between experimental groups (data not shown). At d 7 postpartum, milk yield in both G15 and G35 animals increased 400 g/d (P < 0.05) compared with the GC group (Table 1). An even greater increase in milk production was observed on d 15 postpartum (600–700 g/d; P < 0.05) in the G15 and G35 groups. In addition, milk fat content (Table 2) did not differ (P = 0.750) among groups on d 7 and 15 postpartum. Milk protein content decreased 0.2% in the G35 goats at d 7 after kidding compared with the GC group, because of the increased milk yield, but the milk components were similar among experimental groups at d 15 postpartum. Both lactose and solid nonfat percentage values on d 7 postpartum were lower (P < 0.05) in the supplemented groups than in the controls, but this reduction was not observed on d 15 after kidding (Table 2).


View Full Table | Close Full ViewTable 2.

Means (±SEM) for different milk components across time in lactating goats kept under rangeland conditions in northern Mexico

 
7 d postpartum
15 d postpartum
Treatment1 Fat, % Protein, % Lactose, % NFMS,2 % Fat, % Protein, % Lactose, % NFMS, %
GC 3.9 ± 0.3a 4.0 ± 0.2a 5 ± 0.1a 9.8 ± 0.1a 3.7 ± 0.4a 3.7 ± 0.4a 4.5 ± 0.1a 8.9 ± 0.4a
G15 4.3 ± 0.3a 4.0 ± 0.2a 4.6 ± 0.1b 9.4 ± 0.2b 4.2 ± 0.3a 3.6 ± 0.1a 4.7 ± 0.1a 8.9 ± 0.1b
G35 4.5 ± 0.4a 3.8 ± 0.1b 4.8 ± 0.0b 9.2 ± 0.1b 3.7 ± 0.4b 3.5 ± 0.1a 4.8 ± 0.0a 8.9 ± 0.1b
a,bWithin a column, means without a common superscript differ (P < 0.05).
1GC = nonsupplemented does; G15 = goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum; G35 = same supplementation as G15 but from 35 d before until 7 d after kidding.
2NFMS = nonfat milk solids.

Serum glucose levels (41.5 ± 3.46 mg/dL) did not differ (P = 0.545) among treatment groups. However, serum glucose levels were 4.5 mg/dL higher at parturition compared with pre- or postpartum periods. Similarly, blood serum protein (18.3 ± 1.06 mg/dL) and cholesterol (41.7 ± 2.56 mg/dL) levels did not differ (P > 0.1) among experimental groups. Dam nutrition during the last trimester of gestation did affect (P < 0.01) kid weights at birth and at d 7 and 15 postpartum (Table 3).


View Full Table | Close Full ViewTable 3.

Means (±SEM) for kids BW at birth and at 1 and 2 wk of age when born to dams kept under rangeland conditions in northern Mexico

 
BW, kg
Treatment1 Parturition 7 d of age 15 d of age
GC 3.4 ± 0.2a 4.6 ± 0.2a 5.6 ± 0.2a
G15 3.6 ± 0.2a 5.2 ± 0.2b 6.6 ± 0.2b
G35 3.8 ± 0.1b 5.3 ± 0.2b 6.9 ± 0.2b
a,bWithin a column, means without a common superscript differ (P < 0.05).
1GC = nonsupplemented does; G15 = goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum; G35 = same supplementation as G15 but from 35 d before until 7 d after kidding.

There were treatments effects on dam behavior, as approaches of dams to their own or alien offspring was higher (P < 0.05) in the G35 than the other treatments. However, the GC goats spent more time in the proximity zone near the stimulus kids than the G15 or G35 goats. None of the goats from any group discriminated against the alien kids. Prepartum nutritional supplementation also affected (P < 0.05) vocal activity of both the does and their kids, with the G15 goats showing the greatest number of high- or low-pitched bleats values (Table 4). The total number of high- and low-pitch bleats was higher (P < 0.05) in the G35 than in the other treatment groups. Dams emitted more high- and low-pitched bleats than their kids. The number of bleats emitted by the own and the alien kids did not differ in any experimental group. Both approaches of kids to their own or alien dams were higher (P < 0.05) in kids from G35 dams than in the G15 or GC groups. There was no treatment effect for either dams or kids (P > 0.05) in their preference index at 4 or 8 h postpartum, respectively (Table 5). The latency to reach their mother in the kids from the G35 was lower than the other groups (P < 0.05); however, there was no treatment effect for kid discrimination of their own or an alien dam (Table 5).


View Full Table | Close Full ViewTable 4.

Means (±SEM) for vocal activity, time spent with stimulus animals, and approaches of kids (4 h postpartum) and dams (8 h postpartum) during a 5-h period in goats kept under rangeland conditions in northern Mexico

 
Approaches2
Contact between animals, s
High-pitched bleats
Low-pitched bleats
Treatment Own Alien Own Alien Own Alien Own Alien
Dams, 4 h postpartum
    GC 1.0 ± 0.4a 0.9 ± 0.3a 40.7 ± 19.5a 57.3 ± 36.5a 3.8 ± 1.9a 3.0 ± 1.5a 15.8 ± 6.8a 16.4 ± 6.1a
    G15 0.7 ± 0.5a 0.4 ± 0.3a 9.7 ± 4.9c 6.0 ± 3.7c 2.6 ± 2.5a 3.3 ± 3.0a 1.8 ± 1.2b 1.5 ± 1.1b
    G35 1.3 ± 0.5a 0.9 ± 0.2a 25.1 ± 11.5b 11.9 ± 5.9b 8.6 ± 4.0b 4.6 ± 2.3a 6.3 ± 2.8b 4.4 ± 2.0b
Kids, 8 h postpartum
    GC 0.3 ± 0.2a 0.3 ± 0.2a 0.3 ± 0.2a 0.3 ± 0.2a 2.1 ± 1.5a 1.0 ± 0.7a 0.8 ± 0.8a 0.2 ± 0.2a
    G15 0.2 ± 0.2a 0.2 ± 0.2a 6.2 ± 6.9a 0.2 ± 0.2a 1.8 ± 1.9a 0.4 ± 0.4a 0.4 ± 0.4a 0.1 ± 0.1a
    G35 0.8 ± 0.2b 0.9 ± 0.3b 19.6 ± 11.2a 15.7 ± 7.7b 2.9 ± 0.9a 2.1 ± 0.7b 3.4 ± 1.9a 0.3 ± 0.2a
a–cWithin a column, means without a common superscript differ (P < 0.05).
1GC = nonsupplemented does; G15 = goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum; G35 = same supplementation as G15 but from 35 d before until 7 d after kidding.
2Approaches represents the approaches of the test animal to their offspring or dam. Contact between animals represents the time spent by the animals seeking the stimulus animal. High-pitched bleats refers to the loud calls produced with the mouth open. Low-pitched bleats refers to the quiet vocalizations produced with the mouth closed.

View Full Table | Close Full ViewTable 5.

Means (±SEM) for correct/incorrect choices, preference index, and latency of entrance of kids (4 h postpartum) and dams (8 h postpartum) during a 5-h period in goats kept under rangeland conditions and supplemented with concentrate 35 or 15 d prepartum and 1 wk postpartum

 
Latency to make contact
Treatment1 Correct/incorrect choices2 Preference index Own Alien
Dams, 4 h postpartum
    CG 0.9 ± 0.2a 0.0 ± 0.1a 121 ± 26.6a 127 ± 26.4a
    G15 0.4 ± 0.1a 0.2 ± 0.1a 247 ± 15.6b 216 ± 24.0a
    G35 1.2 ± 0.2a 0.3 ± 0.1a 126 ± 19.4a 188 ± 25.4a
Kids, 8 h postpartum
    GC 0.3 ± 0.0a 0.0 ± 0.0a 223 ± 28.5a 257 ± 19.2a
    G15 0.2 ± 0.0a 0.1 ± 0.1a 263 ± 14.6a 282 ± 7.9a
    G35 0.5 ± 0.1a 0.1 ± 0.1a 195 ± 19.5a 140 ± 23.2b
a,bWithin a column, means without a common superscript differ (P < 0.05).
1GC = nonsupplemented does; G15 = goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum; G35 = same supplementation as G15 but from 35 d before until 7 d after kidding.
2Number of correct/incorrect choices (approaches) to their own dam or kid. Preference index for own or alien kid, calculated as (time spent near the mother – time spent near the alien ewe)/(total time spent near either ewes). Latency to make contact refers to the time taken to make contact with either the own or alien animal at the end of the test area.

DISCUSSION

Live Weight of Dams and Kids

Results of this study showed a progressive effect of feed supplementation before parturition. Does in the G35 group were 3.1 kg heavier at parturition and had a 0.2 greater BCS than GC goats, with the G15 group having weights at parturition that were intermediate between the G35 and GC groups. These results agree with Oyeyemi and Akusu (2002) and Mahboub et al. (2013), who showed that body mass gain in supplemented goats was greater than nonsupplemented groups when grazing low-quality rangelands. These results for BW are consistent with other reports documenting the effect of protein and energy supplementation of goats consuming poor-quality forage during late gestation (Madibela et al., 2002; Malau-Aduli et al., 2004; Sahu et al., 2013).

The weights of kids from the G15 and G35 groups were higher than that of GC kids. This trend is consistent with the observed higher live weight of their dams. Certainly, the offspring of the G35 dams at d 7 and 15 reflected the nutritional advantages of these groups. Goats from the G15 and G35 were able to provide more milk to their kids, who attained 23% higher weights at d 15 of age compared with kids from the GC goats. These results emphasize the advantages of supplemental feeding during late gestation in range goats with positive effects on both dams and kids. These results are in close agreement with other studies where feeding concentrate to grazing goats during pregnancy increased the birth weight of kids (Nnadi et al., 2007; Mahboub et al., 2013).

Milk Yield and Composition

Both G15 and G35 groups had increased milk yield at the beginning of lactation compared with controls. Malau-Aduli et al. (2004) also noted this same increase in milk yield for pregnant goats given a supplement while grazing. Other studies have reported no beneficial effects of feed supplementation during gestation on milk yield in grazing goats (Saha et al., 2012). The higher milk yield of the G15 and G35 goats suggest that they had a higher availability of nutritional precursors for milk synthesis.

As expected, the highest concentration of milk protein, fat, lactose, and solid nonfat protein was found at parturition and these levels dropped at d 15 after kidding. Milk fat, protein, and nonsolid fat yields were higher in the control group compared with the 2 supplemented groups, reflecting the negative correlation between milk yield and milk components (Analla et al., 1996). The concentration of milk components increased when milk yield decreased as a result of changes that occurred in the synthesis of components in milk.

Serum Blood Metabolites

Serum glucose levels sharply increased in all the experimental groups and then decreased on d 7 and 15 after kidding, as also reported by Sadjadian et al. (2013) and Magistrelli and Rosi (2014). Hyperglycemia is a metabolic disturbance caused by cortisol release during the terminal stages of labor (Jenkin and Young, 2004), which increases blood glucose by stimulating both hepatic glycogenolysis and by increasing gluconeogenesis from nonglycidic precursors (McDowell, 1983). Serum glucose level was not affected by feed supplementation. However, concentration of blood glucose has been used to monitor the nutrient status of goats, because this metabolite decreases when goats are subjected to restrictions in energy (Hussain et al., 1996) or because of a reduction in concentrate supplementation (Landau et al., 1993).

In the present study, goats had average serum glucose concentrations of 58.65, 130.57, and 52.9 mg/dL at –35 d, parturition, and + 7 d, respectively. Such trends are inconsistent with the plane of nutrition, suggesting that goats on a low nutritional plane decreased metabolic rate and the required energy for maintenance (Hornick et al., 2000). Additionally, crossbred goats used in the present study probably minimized their energy requirements for maintenance during periods of low energy intake as it has been previously reported (Silanikove, 2000). Another possibility is that the GC goats may have used catabolism of muscle protein to support gluconeogenesis. During fasting, propionate supply is reduced to negligible quantities such that glycerol and AA from adipose and muscle tissue, respectively, are major precursors of glucose (McDowell, 1983). Comline and Silver (1972) found a pronounced hyperglycemia in ewes during parturition; its extent and duration varied in different animals, but it was always associated with the terminal stages of labor and especially with the actual delivery. According to these authors, a likely cause for this phenomenon is the discharge of adrenaline stimulated by expulsion of the fetus and possibly traction on the umbilical cord transmitted to the uterus.

Cholesterol concentration, in the absence of excess dietary energy intake, reflects the capacity of the animal to mobilize body fat reserves (Ingraham and Kappel, 1988). In goats, blood cholesterol concentration is also associated with BCS (Cabiddu et al., 1999). This suggests that, in the present study, feed supplementation did not alter catabolism of fat reserves, which is inconsistent with previous studies (Cabiddu et al., 1999; Mellado et al., 2003). The same was true regarding serum concentrations of protein, as there were no differences in serum protein concentrations among experimental groups, suggesting that the GC goats did not have a deficiency in their nutrient supply. However, the control animals lost more weight, exhibited a lower BCS, and had lower milk yields than the supplemented animals after parturition, indicating nutritional deficiencies and stress.

Maternal and Young Behavior at Parturition

Feed supplementation before kidding did not alter the approach of dams toward their own or alien kids, but GC goats spent an increased period of time in contact with either their own or an alien kid compared with the G15 and G35 groups. Similarly, GC goats emitted a greater number of low-pitched bleats when exposed to their own or alien kids 4 h after parturition compared with the supplemented groups. All experimental groups, except the G35, showed an increased preference or a faster latency to traverse the distance to either their own or an alien doe or kid. These results suggest that feed supplementation to late-gestation goats grazing on marginal rangelands did not result in a heightened maternal response or an increased ability to recognize kids by their mother (Terrazas et al., 2009; Dwyer et al., 2003). In general, underfed ewes take longer to interact with their lambs, display more aggression, spend less time grooming and more time eating after birth, and are more likely to desert their lambs (Nowak and Poindron, 2006). Interestingly, however, a greater maternal investment of time spent in contact between animals shortly after parturition was observed in the GC goats. Such maternal behavior suggests that thinner goats with low energy reserves do not show a reduction in maternal behavior. Therefore, different factors in the mother, other than BCS, are likely involved in the development of preferential nursing of dams by their offspring after parturition (Terrazas et al., 2002). Mellado et al. (2012b) also proposed that nutritional stress during gestation under arid range conditions does not interfere with the neonate’s level of alertness and arousal in goats. There were no discernible differences in mother–young recognition due to supplementation. In previous studies in sheep using 2-choice tests, ewes discriminated their own lambs from alien lambs only at 4 h postpartum, whereas lambs discriminated their mothers at 12 h (Searby and Jouventin, 2003; Pfister et al., 2006; Sèbe et al., 2007). Nonetheless, prepartum nutritional supplementation affected vocal activity of both the does and their kids, with the goats in the G15 group having the greatest number of high- or low-pitched bleats and the total number of high- and low-pitch bleats was highest in the G35 group. Sèbe et al. (2007) stated that vocal behavior of ewes and their neonates plays an important role in the development of a preferential relationship and the maintenance of mother–young bonding very early after parturition. Moreover, vocal communication is a very important element in the development of a preferential response of the newborn lamb for its mother (Sèbe et al., 2010). Low-pitched bleats play a crucial role in this process. These low-pitched maternal bleats are emitted almost exclusively in the presence of the lamb and decline over time. These sounds are thought to calm the newborn and to provide cues for later recognition of the dam. High-pitched bleats increase with time and they are used for distal communication (Nowak and Poindron, 2006).

In summary, targeted high-energy and high-protein peripartum supplementation not only enhanced dam BW and kid birth weight but also increased milk yield and altered milk composition. Nutritional supplementation promoted increased searching activity in the dams after parturition while positively affecting the general behavior of the dam or the kid. Results point out that peripartum nutritional supplementation should be considered a key investment strategy rather than an economic charge, particularly under marginal production systems.

 

References

Footnotes


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