Effect of weaning on epidermal growth factor and its receptor messenger RNA levels in various tissues of piglets

Weights of pancreas, liver, and stomach, and total DNA of pancreas and stomach mucosa per body weight were greater (P < 0.05) in weaned piglets than suckling ones at 30 d of age. There was no effect (P > 0.05) of weaning on epidermal growth factor (EGF) and EGF receptor (EGFR) messenger RNA levels in liver, stomach, duodenum, and skeletal muscle. Messenger RNAs of EGF in pancreas increased following weaning in piglets of 27 (P = 0.0001) and 30 (P = 0.004) d of age, indicating a possible involvement of EGF in pancreatic development during this period. Key words: Weaning, EGF, EGFR mRNA, Pig tissues

The breed of dam by sex of calf interaction effect on beef cattle weaning weight and cow efficiency

A portion of a data set reported on in a previous paper was combined with additional data to evaluate the effects of dam breed × calf sex interaction and other sources of variation on beef cattle weaning weight and cow–calf efficiency of feed utilization. Within the Angus × Hereford dam group, the sex difference (male minus female calf) was 8.4% for weaning weight and 8.1% for efficiency ratio (calf weaning weight divided by dam and calf total digestible nutrients). Within the Simmental × Hereford group, the sex difference was 15.5% for weaning weight and 12.3% for efficiency ratio. Key words: Weaning weight, cow efficiency, beef cattle

EFFECTS OF DATE OF WEANING ON SUBSEQUENT PERFORMANCE OF BEEF COWS AND THEIR FEMALE CALVES

1233 April/May born calves were weaned either on 30 Sept. (EW) or 31 Oct. (LW) to assess the effects of weaning date on subsequent performance of their dams and female calves. Cows in the EW group lost less weight than those in the LW group in the month of October (0.003 vs. 0.48 kg d−1, P < 0.05). Dam's breed group, year and the interaction between year and age of dam also had significant effects on weight change during October. Cows generally lost weight between weaning and the next calving and the two weaning groups were similar in body weight at calving and reproductive performance. The reproductive performance of the EW and LW female calves were also quite similar. It can be concluded that weaning April/May born calves in September rather than October would not influence the subsequent production of the dams or their female calves, but would probably reduce their maintenance requirements as they enter the cold season in better condition. Key words: Weaning date, beef cows, reproduction, weight changes