What are the effects of weaning age and pre-breeding diet on replacement beef heifers?
The answer to the question may fall somewhere between the management decisions of nutrition and economic feasibility. By looking at studies focused on weaning age and different crude protein diets I hypothesize that results will show differences with age of onset of puberty, pregnancy rates, lactation performance, and offspring performance. Story et al. found that several problems have been associated with creep feeding and early weaning management of replacement heifers. According to one economic study, using an early weaning regimen could raise producer costs by 12.8% in comparison to normal weaning of heifer calves (Story et al., 2000).
Effects of calf…show more content… The normal weaned pairs were placed back in a pasture of bahiagrass, forage relatable to ______ in Oklahoma. The early weaned groups remained in drylot pens and were fed a free choice diet of long-stem hay and a preconditioning ration with 14% CP and 1.0% fat (as fed) eaten at an average of 0.90 kg/heifer daily, no health problems were noted during this…show more content… Group 2 consisted of early weaned heifers (n=10) that remained in the dry lot for the duration of the study and were fed a high concentrate diet at 3.5% of body weight the entire time. Group 3 was early weaned and fed a high concentrate diet at 3.5% of body weight in a drylot for 90 days and then moved onto a bahiagrass pasture and fed a high concentrate diet at 1% of body weight for the last 90 days of feeding. The final group was comprised of early weaned heifers (year 1; n=10 grazed until day 60) (year 2; n=8 grazed until day 90) grazed on ryegrass and fed a high concentrate diet at 1% of body weight for the first half of the feeding and then moved to bahiagrass pastures and continued to consume the high concentrate diet at 1% until the end of the feeding schedule. On day 60 and 80, all heifers were vaccinated and treated for internal parasites. At day 180 Group 1 heifers were weaned and all heifers were placed into bahiagrass pastures and supplemented with the high concentrate diet at 1.5% of body weight until day 390. All of the heifers were tested for IGF-1 concentrations on days 90, 180, and 270 and for progesterone every ten days from days 180 through 390 via plasma samples to determine the age of the heifer at onset of puberty. On day 330, yearling aged Brahman X British bulls were placed to heifers at a
