This study determined the responses of early lactating goats fed varying amounts of rumen-inert fat. Forty multiparous high producing Alpine does in the first 2 wk of lactation were assigned randomly to four isonitrogenous dietary treatments containing 0, 3, 6, and 9% added fat. The study consisted of a 2-wk preliminary and a 10-wk experimental period. Feed intake, blood glucose, and rumen pH were not affected by dietary treatments. Body weight gain and milk production decreased linearly as dietary fat increased. Peak production was higher with 3% added fat than with 6 and 9%. The SCC, total solids, and lactose contents of milk were unaffected by fat percentage. Milk fat percentage increased linearly as fat percentage increased; milk protein content was highest at 6% dietary fat addition. The rumen-inert fat tended to increase long-chain fatty acids and to reduce short-chain fatty acids of milk. These findings suggest that fat supplementation at 3% of the total diet can increase fat percentage in milk from high producing dairy goats in early lactation.

Sixty-three multiparous Alpine does were blocked by pregnancy type (single vs. multiple) on d 90 of pregnancy and assigned to one of nine diets to evaluate the interaction of prepartum protein and energy intake on BW change, kidding, and subsequent production and composition of milk. Treatments were factorial with three percentages of CP (8.5, 11.5, and 14.5% of DM) and three concentrations of metabolizable energy (1.80, 2.16, and 2.53 Mcal/kg of DM). Does were fed for ad libitum intake during pregnancy and switched to a lactation diet (16% CP and 2.35 Mcal of metabolizable energy/kg of DM) after parturition. Milk production and composition were recorded for the first 15 wk of lactation. Prepartum BW gain increased quadratically as protein amount increased but was unaffected by energy. Kidding rate, litter weight, and gestation length were unaffected by protein or energy amounts. Milk production in the subsequent lactation increased quadratically in response to prepartum CP (2.59, 3.26, and 3.07 kg/d for 8.5, 11.5, and 14.5% CP, respectively). Milk production increased linearly in response to prepartum metabolizable energy concentration (2.63, 3.05, and 3.26 kg/d for 1.80, 2.16, and 2.53 Mcal/kg of DM, respectively). Milk fat percentage increased linearly in response to increased prepartum energy. Production of milk fat, protein, SNF, FCM, and SCM were affected quadratically by increased prepartum CP and linearly by prepartum energy, following the pattern for milk production. The present recommendations for prepartum CP and energy appear to be adequate for gestation and subsequent lactation performance of dairy goats.

No abstract

Thirty-six Holstein cows were fed a diet of 50% concentrate and 50% corn silage (dry matter) for 12 wk postpartum. Treatments were 0, .4, and .8% magnesium oxide with or without .8% sodium bicarbonate in a 2 X 3 factorial arrangement. Dry matter intake was not different among treatments although the combined buffers had higher intake. Milk production was higher for the .4% magnesium oxide treatments either alone or with sodium bicarbonate as compared with either the 0 or .8% magnesium oxide treatments. Ruminal pH was increased with addition of sodium bicarbonate either alone or together with magnesium oxide. Dietary addition of .4% magnesium oxide either alone or with sodium bicarbonate increased total volatile fatty acid in ruminal fluid. Propionate and valerate were depressed in both of the combined buffered diets. Fecal pH was increased with magnesium oxide addition either alone or with sodium bicarbonate. Increasing magnesium oxide increased magnesium in plasma. No interactions in animal performance were significant for the two buffers.

Forty multiparous Alpine does (mean BW of 61.5 kg) were utilized in a 13-wk trial to investigate the effects of a TMR differing in CP amount (13 or 17%) and source (solvent-extracted soybean meal or heat-treated soybean meal with or without urea) on lactational performance. Protein supplements contributed 30% of the N in 13% CP diets and 50% of the N in 17% CP diets. All diets were isoenergetic (2.5 Mcal of metabolizable energy/kg of DM) and were fed for ad libitum intake for the entire trial. Mean DMI (2.88 kg/d), milk production (2.65 kg/d), milk fat (4.05%), milk protein (2.68%), milk lactose (4.54%), and milk SNF (7.81%) did not differ among dietary treatments. Plasma urea N was greater (23.2 vs. 10.9 mg/dl) in does receiving the 17% CP diets; however, blood hematocrit (27.4%), beta-hydroxybutyrate (843 microM), plasma glucose (68.8 mg/dl), NEFA (600 mu eq/dl), and plasma total protein (74.% g/L) were not significantly affected by treatment. The apparent absence of a dietary effect on lactational performance may be due to the high DMI of the does (4.7% when expressed as DMI per kilogram of BW) and high CP intake providing a surfeit of protein relative to requirements.