Davood Zahmatkesh

The positive effects of nucleotide (NU) supplementation in milk replacer have been elucidated in infants and in dairy calves; however, NU addition to whole milk has not been evaluated previously. This study aimed to assess NU supplementation in the whole milk on calf growth and health. Thirty Holstein calves (body weight: 39.1 ± 1.0 kg; 3 d after birth) were randomly assigned to the following treatments: whole milk without any supplementation (NU0), whole milk + 0.5 g/d added a NU-containing supplement to whole milk (NUCS0.5), and whole milk + 1 g/d added a NU-containing supplement to whole milk (NUCS1). Calves were weaned at d 55 and stayed on study until d 75. Calves had free access to feed and water throughout the study. Dry matter intakes (DMI) were similar among treatments (p > 0.05) during the pre-weaning period; however, increasing NU resulted in a linear (p < 0.05) increase in DMI during the post weaning period (2158, 2432, and 2518 g/d for NU0, NUCS0.5, and NUCS1, respectively). Treatments did not affect body weight (BW) at the first and second month of study, but final BW linearly increased as NU was added (87.1, 90.6, and 95.4 kg for NU0, NUCS0.5, and NUCS1, respectively). Neither pre-weaning average daily gain nor post-weaning average daily gain was affected by treatments; accordingly, feed efficiency was similar among treatment groups. Days with loose fecal score were linearly decreased as NU was added to whole milk during the first month of life, while the fecal score did not differ among treatments until the end of the study. No difference was observed in the skeletal growth of calves in the current study. Therefore, it can be concluded that NU supplementation in the whole milk has some beneficial effects on calf performance in terms of final BW, post-weaning DMI, and less days with loose feces.

This research paper addresses the effect of different grouping strategies of fresh cows on total lactational and reproductive performance. Hundred-sixty multiparous Holstein cows were enrolled in a completely randomized design and assigned to one of following treatments: 21 days in fresh pen with 12.5 kg/day concentrate (C21,n= 60), 10 days in fresh pen with 12.5 kg/day concentrate (C10,n= 50) and 10 days in fresh pen with 10 kg/day concentrate (L10,n= 50). Although there were no differences among treatments within the first 10 days in milk (DIM), C10 and L10 cows tended to produce more milk than C21 from 10 to 21 DIM. In addition, greater milk yield was obtained in C10 and L10 cows during 22–28 DIM and 29–70 DIM. Higher production in early lactation resulted in a tendency for greater milk production for C10 and L10 cows throughout a 305 days lactation. There was no difference in productivity between C10 and L10 groups at any time point. No blood metabolites (Ca, P, non-esterified fatty acids andβ-hydroxy butyrate) were affected by treatments. Pregnancy at first, second and third service was 38, 39 and 40%, respectively, which were not influenced by the days in fresh pen or concentrate allowance. Collectively, our results for the first time suggest that fresh cow grouping strategy has a long-term effect on productivity but that adding 2.5 kg/day concentrate has no effect on milk yield in fresh pen.