No abstract

This study investigates the newborn thermoregulatory responses to cold and the performance of calves fed different colostrum volumes. Thirty newborn Holstein calves were blocked by birth body weight (BW; 39.4 ± 6.5 kg) and fed different high-quality colostrum volumes: 10%, 15%, or 20% of BW, which was split and fed at 2 and 8 h after birth. At 24 h of life, calves were placed in a chamber at 10 °C for 150 min. Skin and rectal temperature (RT), heart and respiratory rate, and shivering were measured every 15 min. Blood samples were taken every 30 min. After the cold challenge, calves were housed in ambient temperature (26.8 ± 5.9 °C), with free access to water and concentrate and received 6 L/d of milk replacer. Feed intake, fecal score, and RT were recorded daily, until 56 d of age. Blood samples, BW, and body measures were taken weekly. During the cold challenge, prescapular temperature and total serum protein were greater for calves fed 15% or 20%. Leukocytes increased preweaning, presenting higher values for calves fed 20%. Even though there was a benefit for the calf submitted to cold stress on the first day of life, feeding higher volumes of colostrum resulted in no differences in performance during the preweaning phase. Nevertheless, calves fed a higher volume of colostrum (20% BW) presented increased immune responses during the preweaning phase.

No abstract

No abstract

This study aimed to evaluate the performance and metabolic changes in dairy calves supplemented with lysine and methionine in milk replacer (MR) or starter concentrate (SC). Male Holstein calves (n = 45) were blocked and distributed in Control without supplementation (1) and; Lysine and Methionine supplementation to achieve an intake of 17 and 5.3 g/d in the SC (2) and to achieve of 17 and 5.3 g/d in the MR (3). MR was fed (6 L/d) until the 8th week of life when weaning occurred. Calves were followed until the 10th week of age. Feed intake was measured daily. Weight and body measurements were registered weekly. Blood samples were collected biweekly to evaluate the intermediate metabolism. The AA supplementation resulted in lower body weight at weaning and week 10. Calves fed SC Lys:Met had lower SC intake and lower total feed intake at weaning when compared to control. Calves fed control had higher heart girth, hip-width, and plasma glucose concentration. The supplementation with Lys and Met did not benefit dairy calves’ performance nor metabolism in this study. Supplementation through the MR was more efficient than SC to result in adequate daily intakes of AA. Further studies are needed to understand the negative effects of AA on calf starter intake.