Influence of pre- and post-calving pasture allowance on hill country beef cow and calf performance

Abstract

Sixty pl egnant beef cows of Friesian, 7/8 Friesian X Jersey, and Angus genotypes 3 years of age and older were used. At 56 days before calving, each cow was allocated to 1 of 2 daily pasture DM allowance levels: 20 ("20") and 8 ("8") kg DM per cow. At calving cows were re-assigned to daily pasture allowances of 20 ("20-20" and "8-20") or 8 ("20-8" and 8-8") kg DM per cow for 56 days post-partum. At 56 days after calving, the cows were grouped into a single mob and given a daily allowance of 18 kg DM per cow throughout mating and until weaning. Despite similar pre-calving weights, "20" cows were 36 kg heavier (P < 0.01) immediately after calving than "8" cows. Forty-two days after calving the visually assessed condition scores of "20" cows remained consistently higher (P < 0.05) than the score of "8" cows. Mean DM intakes (kg/cow/day) for "20" and "8" cows before calving were 9.5 and 6.3 respectively. Mean DM intakes (kg/cow/day) (and % DM utilisation rates) for "20" and "8" cows before calving were 9.5 kg (47.6%) and 6.3 kg (78.2%) respectively. At 56 days after calving, "20-20" and "8-20" cows weighed 520 kg and ')02 kg respe('tively and were heavier (P < 0.01) than "20-8" and "8-8" cows (340 kg and 392 kg); condition scores were significantly different (P < 0.05) at 6.8, 6.0, 3.4, and 2.5 respectively. Treatments did not affect calf weights until 56 days of age when calves of "20-20" (76 kg) and "8-20" (81 kg) cows were heavier (P < 0.05) than those of "8-8" cows (67 kg) ; calves out of "20-8" cows (74 kg) were intermediate. Intakes (kg DM/cow/day) for " 20-20", "8-20", "20-8", and "8-8" cows during the 56 days after calving were 10.5, 11.7, 6.8, and 7.0 kg respectively. From 56 days post-partum until weaning, gains in cow live weight (and condition score) were -5 kg (-0.2) , 44 kg (2.0), 4 kg (-0.1), and 58 kg (2.7) for " 20-20", "20-8", "8-20", and "8-8" cows respectively. Corresponding calf weight gains (kg) were 81, 83, 83, and 83. The mean intervals (days) from calving to first oestrus were 72, 80, and 69 for "20-20", "20-8", and "8-20" cows respectively, shorter (P < 0.05) than the 97 days of "8-8" cows. Pre-calving pasture allowance had no effect on interval from calving to first oestrus or pregnancy rate, but both these traits were affected by post-calving allowance.417

Effects of pasture allowance level after calving on performance of beef cows on hill country

“…The absence of any lasting effect of cow nutrition on calf weight agrees closely with similar work by Hodgson et al (1980), Smeaton et al (1982), and Nicoll (1979). The cows apparently buffered their calves against low nutrition within the range encountered in this trial.…”

“…The decline in weight shown by all groups of cows from about 80 days after calving until weaning was also observed by Nicoll (1979) and Smeaton et al (1982). It may have been the result of declining herbage quality as the season advanced -a phenomenon also observed by Gillingham (1974), Jagusch et al (1978), and Smeaton et al (1983).…”

“…For every kg heavier at birth, the calves before and after calving were a little lower than those Table 5 Apparent intake by T12 cows (kg DM/cow per day), and comparison with recommendations (Scott et al 1980 observed by Nicoll (1979) for cows on similar allowance levels. Cow weight at mating was closely related to pasture disappearance, residual herbage, and pasture allowance.…”

“…However, in a hill country trial at Whatawhata, Nicoll(1979) found that offering 2 different pasture allowances (8 or 20 kg DM/cow per day) before calving did not affect either the interval from calving to first oestrus, or the pregnancy rate of the cows, provided the pasture allowance was high (20 kg DM/cow per day) after calving. Cows given maintenance allowance (8 kg DM/cow per day) before and after calving had longer intervals to first oestrus and lower pregnancy rates than those fed the 20 kg DM/cow per day allowance throughout or after calving.…”

Manejo de novilhas prenhes aos 13/15 meses de idade em sistemas a pasto

“…Na CCP houve, no entanto, redução na diferença para 0,2 ponto. Nicoll (1979) citou superioridade de 1,3 ponto de condição corporal pós-parto para vacas com maiores níveis nutricionais no pré-parto. A condição corporal ao parto é provavelmente o fator mais importante a afetar o desempenho reprodutivo de vacas de corte (Morrison et al, 1999) e está correlacionada à condição corporal ao início do acasalamento subseqüente (Sampedro et al, 2000).…”