View Full Table | Close Full ViewTable 1.

Prebreeding blood ketones, serum metabolites, and milk production for 2- and 3-yr-old cows classified as early or late conception in Exp. 1

 
Conception1
Prebreeding measurement EARLY LATE SEM P-value
n 65 62
Blood ketones, µmol/L
    Whole-blood β-hydroxybutyrate 297 371 20 0.04
Serum metabolites
    Glucose, mg/dL 52.9 58.1 1.7 0.02
    Insulin, ng/mL 0.81 0.56 0.07 0.03
    NEFA, mmol/L 501 491 19 0.69
    Serum urea N, mg/100 mL 9.07 9.74 0.48 0.32
    IGF-I, ng/mL 45.78 42.04 3.46 0.42
Milk, g/d
    24-h milk production 5991 6510 335 0.28
    Lactose 298 320 16 0.34
    Protein 159 175 9 0.24
    Solids-non-fat 512 553 28 0.31
    Butterfat 197 215 15 0.41
1Conception date was estimated from calving date in the subsequent year: EARLY = conceived within first 15 d of breeding; LATE = conceived during the remainder of the breeding season.



View Full Table | Close Full ViewTable 2.

Calving date and reproductive measurements for 2- and 3-yr-old cows classified as early or late conception in Exp. 1

 
Conception1
Measurement EARLY LATE SEM P-value
Calving date,2 Julian d 62 65 2 0.19
Reproductive measurements
    Resumption of estrus,3 d 71 78 2 0.04
    Conception date,4 d 80 99 1 <0.01
    Estrus to conception,5 d 9 21 2 <0.01
    BW nadir, d 59 57 4 0.71
    Nadir to estrus,6 d 12 21 5 0.18
1Conception date was estimated from calving date in the subsequent year: EARLY = conceived within the first 15 d of breeding; LATE = conceived during the remainder of the breeding season.
2Calving date of the study year.
3Interval from calving to resumption of estrus.
4Interval from calving to estimated day of conception.
5Interval from resumption of estrus to estimated day of conception. 6Interval from BW nadir to resumption of estrus.6Interval from BW nadir to resumption of estrus.



View Full Table | Close Full ViewTable 3.

Cow BW and BW change, BCS, and calf BW for 2- and 3-yr-old cows classified as early or late conception in Exp. 1

 
Conception1
Measurement EARLY LATE SEM P-value
BCS2
    Calving 4.5 4.6 0.04 0.81
    Branding 4.0 4.1 0.05 0.12
    Weaning 4.6 4.7 0.06 0.80
Cow BW, kg
    Calving 449 454 5 0.41
    Nadir 368 368 4 0.97
    Begin of breeding 393 388 5 0.39
    End of breeding 400 408 5 0.19
    Weaning 447 453 5 0.37
Cow BW change, kg
    Calving to begin of breeding −56 −67 3 0.01
    Calving to nadir −81 −87 4 0.24
    Calving to end of breeding −49 −46 4 0.59
    Nadir to end of breeding 32 40 3 0.04
    Nadir to weaning 79 85 3 0.14
    Calving to weaning −2 −1 4 0.87
Calf BW, kg
    Birth 34 33 1 0.46
    Branding3 70 68 2 0.49
    Weaning4 203 205 4 0.67
1Conception date was estimated from the subsequent years calving date: EARLY = conceived within first 15 d of breeding; LATE = conceived during the remainder of the breeding season.
2For BCS, 1 = emaciated, 9 = obese; Wagner et al. (1988).
3Calf BW at branding, adjusted for 55-d BW.
4Calf BW at weaning, adjusted for 205-d BW.



View Full Table | Close Full ViewTable 4.

Cow BW, BCS, calf BW, and circulating concentrations of IGF-I for 2- and 3-yr-old cows classified as early or late conception in Exp. 2

 
Conception date1
Measurement EARLY LATE SEM P-value
n 145 160
Calving date, Julian d 90 92 5 0.49
Conception date2, d 81 111 5 <0.001
Cow BW, kg
    Precalving 451 448 7 0.80
    Prebreeding 426 426 7 0.97
Cow BCS3
    Precalving 5.0 5.0 0.1 0.83
    Prebreeding 4.5 4.4 0.1 0.43
Calf BW, kg
    Birth 33 34 1 0.25
    Weaning4 198 224 3 <0.01
IGF-I, ng/mL 144 130 5 <0.01
1Conception date was estimated from calving date in the subsequent year: EARLY = conceived within the first 15 d of breeding; LATE = conceived during the remainder of the breeding season.
2Interval from calving to estimated conception.
31 = emaciated, 9 = obese; Wagner et al. (1988)
4Weaning BW adjusted for 205-d BW.



View Full Table | Close Full ViewTable 5.

Concentrations of β-hydroxybutyrate (BHB) in precalving and prebreeding serum samples from 2- and 3-yr-old cows classified as early or late conception in Exp. 2

 
Conception1
Measurement EARLY LATE SEM
Precalving BHB
    2-yr-olds 567ax 518ax 24
    3-yr-olds 595ax 710by 36
Prebreeding BHB
    2-yr-olds 382ax 379ax 18
    3-yr-olds 387ax 363ax 28
a,bFor each interaction within timing of sample, means in rows with different superscripts differ (P < 0.05).
x,yFor each interaction within timing of sample, means in columns with different superscripts differ (P < 0.05).
1Conception date was estimated from calving date in the subsequent year: EARLY = conceived within the first 15 d of breeding; LATE = conceived during the remainder of the breeding season.