Effect of protein restriction of Angus cows during late gestation: Subsequent reproductive performance and milk yield

LOPEZ VALIENTE, S; PALLADINO, R.A.; QUINTANS, G.; MARESCA, S.; LACAU-MENGIDO, J.M.; RODRIGUEZ A.M.; LONG, N.M.

The Professional Animal Scientist

American Registry of Professional Animal Scientists (ARPAS)

Año: 2018 vol. 34 p. 261 - 268

1080-7446

The effect of level of CP fed during late gestation onreproductive performance and milk production was studiedin multiparous cows. Sixty-eight pregnant Angus cowswere used. At 121 d prepartum, cows were blocked by BW(409 ± 57 kg) and expected calving date, randomly assignedto a low-protein (LP = 6% CP) or high-protein diet(HP = 12% CP), and allocated to 12 pens per treatment.After parturition, all cows were managed in a single groupuntil weaning. Body weight and BCS were determined atthe start of the experiment, at calving, and at weaning.Nonesterified fatty acids, insulin, IGF-1, and glucose weredetermined every 24 d prepartum and nonesterified fattyacids and glucose every 38 d postpartum. Progesteronewas quantified weekly to indicate luteal activity and estimateinterval to first estrus. Milk production was measureduntil weaning. The HP cows had greater BW gainduring the prepartum period (P < 0.01) and tended togain more BCS (P = 0.06) than LP cows. The prepartumdiet did not affect gestation length (P = 0.44) or intervalfrom calving to the onset of luteal activity (P = 0.35).Pregnancy rates, milk quality, and production were not influencedby dietary treatments. Cows in the HP treatmenthad greater prepartum serum urea concentrations thanLP treatment (P < 0.05). In conclusion, protein level prepartumin multiparous beef cows affected the BW changeat calving, without consequences on reproductive performanceand milk quality and yield.