Effects of Weaning Date and Prepartum Protein Supplementation on Cow Performance and Calf Growth

Abstract

Two experiments evaluated effects of weaning date on cow body condition score (BCS) and calf growth. In Experiment 1, 134 March-calving cows were used in a four-year experiment. Calves were weaned 18 August or 7 November and cows were fed 0 or 0.45 kg protein supplement (42% crude protein) three days per week from 1 December to 28 February while grazing upland range in a 2 by 2 factorial arrangement of treatments. In Experiment 2, spring calving cows (year 1, n 5 97; year 2, n 5 104) were assigned randomly to one of eight weaning dates at 2-week intervals from 19 August to 25 November. In Experiment 1, weaning in August increased cow BCS precalving (P , 0.001) and prebreeding (P , 0.001), but not pregnancy rates (P 5 0.56). Cows fed supplemental protein had greater BCS precalving (P , 0.001) and prebreeding (P 5 0.001) than nonsupplemented cows, but pregnancy rates were similar (P 5 0.27). Calves born to cows fed supplemental protein prepartum had greater weaning weight than calves born to nonsupplemented cows regardless of whether weaning occurred in August (P 5 0.001) or November (P , 0.001). Effects of weaning date on feedlot performance interacted with supplementation treatment. Calves born to cows fed supplement that were weaned in November generated the greatest net returns. In Experiment 2, BCS decreased linearly (P , 0.001) as date of weaning was delayed from August to November. Nursing calf gain increased cubically (P , 0.0004) and weaned calf gain from August to November increased quadratically (P , 0.002). Protein supplementation did not affect cow pregnancy rate, but calves born to cows fed protein supplement had greater pre-and postweaning gains. Cow BCS decreased as weaning date was moved later in the year but cow pregnancy rate was not affected by weaning date. Resumen Dos experimentos evaluaron los efectos de la época de destete sobre la condición corporal de la vaca (BCS) y el crecimiento del becerro. En el experimento 1, 134 vacas que parieron en marzo se usaron en un experimento de cuatro añ os. Los becerros se destetaron el 18 de agosto o el 7 de noviembre y las vacas fueron alimentadas con 0 o 0.45 kg de suplemento proteico (42% PC) tres días a la semana del 1 de diciembre al 28 de febrero mientras apacentaban en un pastizal de tierras altas. Los tratamientos tuvieron un arreglo factorial 2 3 2. En el experimento 2, vacas que parieron en primavera (añ o 1, n 5 97; añ o, 2 n 5 104) fueron asignadas aleatoriamente a una de ocho fechas de destete, con dos semanas de separación entre ellas, del 19 de agosto al 25 de noviembre. En el experimento 1, el destete en agosto incrementó la BCS de las vacas antes del parto (P , 0.001) y antes del empadre (P , 0.001), pero no aumentó las tasas de preñ ez (P 5 0.56). Las vacas suplementadas con proteína tuvieron una mayor BCS antes del parto (P , 0.001) y del empadre (P , 0.001) que las no suplementadas, pero las tasas de preñ ez de ambos grupos fueron similares (P 5 0.27). Los becerros nacidos de las vacas suplementadas con proteína antes del parto tuviero...

Late gestation supplementation of beef cows differing in body condition score: Effects on cow and calf performance1,2

“…However, no difference in BW of supplemented and nonsupplemented cows was noted at weaning (P = 0.16) but there was a tendency (P = 0.08) for supplemented cows to have a greater BCS than nonsupplemented. Our data agrees with numerous reports documenting the effect of protein supplementation of cows consuming poor quality forage during late gestation on BW and BCS (Randel, 1990;Bohnert et al, 2002;Stalker et al, 2007).…”

“…At calving, the difference in BW and BCS between HBCS and LBCS cows remained (P < 0.001), and at weaning, the HBCS cows were still 29 kg heavier (P < 0.001) and had a 0.5 greater (P < 0.001) BCS than LBCS cows. These data agree with those reported by Stalker et al (2007) who showed cows with greater BW and BCS at the beginning of the last trimester of gestation also had greater BW and BCS at calving and at weaning.…”

“…A reduction in live calves at weaning caused by nutrient restriction (Corah et al, 1975) or a lack of supplementation (Stalker et al, 2006) during the last trimester of gestation has been reported. However, like Stalker et al (2007) we did not observe an effect of supplementation on live calves at weaning. Nevertheless, we did observe an effect of cow BCS during the last trimester of gestation on percentage of live calves at weaning which is in contrast to the results reported by Stalker et al (2007).…”

“…However, like Stalker et al (2007) we did not observe an effect of supplementation on live calves at weaning. Nevertheless, we did observe an effect of cow BCS during the last trimester of gestation on percentage of live calves at weaning which is in contrast to the results reported by Stalker et al (2007). The difference between the two studies could be because the BCS of cows in our study was lower.…”

Calving date and wintering system effects on cow and calf performance I: A systems approach to beef production in the Nebraska Sandhills

“…Because Jun-and Augcalving cows rapidly gained BCS postweaning, Jun-and Aug-born calves could be weaned at older ages without decreasing cow BCS at weaning below the BCS of Mar-calving cows at weaning. Stalker et al (2007) demonstrated calf efficiency of gain is improved with later weaning dates and that it is preferable to keep the calf with the cow if it does not compromise cow BCS or rebreeding performance. 1 Number of pregnant cows that started the study each year.…”