Effect of pregnancy on milk production and bodyweight from identical twin study.

摘要: The energy requirements of the fetus through pregnancy have been previously investigated in several slaughter experiments, and many studies attempted to estimate effect on milk production. Data from 154 pasture-based dairy cows (77 twin pairs) were subjected a retrospective analysis determine production body weight. A decline yield 126 d was observed twins that pregnant, but small insignificant until 147 gestation (at 33 wk lactation), after which pregnant produced less (0.8 kg/cow per day). Protein fat concentration increased 77 133 gestation, respectively. protein not affected by 168 (0.06 day) (0.04 compared with their nonpregnant twins. Body weight higher 90 continued increase end lactation (182 pregnancy). Fitted splines showed concentrations throughout lactation, (20 g/cow during breeding season (between 12 17 lactation) Higher secreted (net for also found season. Although pregnancy-related reductions yields milk, fat, occurred midgestation, overall effects this pasture-based, seasonal calving system small.