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Dairy goats
Influences of prepartum
protein and energy concentrations for dairy goats during pregnancy and 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, solids-non-fat, fat-corrected milk, and solids-corrected milk 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. Top of PageImplication of feeding isoenergetic diets containing animal fat on milk composition of Alpine does during early lactation Lactation and digestion trials were conducted to test the hypothesis that supplemental animal fat in goat diets would alleviate low fat content and decrease concentrations of fatty acids responsible for flavor problems in goat milk during early lactation. In a 17-wk trial, 14 Alpine does were assigned randomly to isonitrogenous and isoenergetic diets with either 0 or 5% animal fat in a double crossover experiment. Intakes of NDF and ADF were higher in goats fed 5% dietary fat, but intakes of other nutrients were similar between treatments. Total VFA concentration was lower, and acetate and butyrate proportions were higher, in does fed 5% fat. Plasma NEFA, triglyceride, and total cholesterol were higher in does fed 5% fat. Milk fat content was higher in does fed 5% fat (3.8 vs 3.1%). Yields of 4% fat-corrected milk and solids-corrected milk were similar between treatments. No differences were observed in milk cholesterol content as a result of dietary animal fat. Milk caproic, caprylic, capric, lauric, and myristic acids were lower, whereas palmitic, stearic, and oleic acids were higher, in milk from does fed 5% fat. Efficiencies of feed, energy, and protein for milk yield were not altered by supplemental animal fat in the diet. We concluded that an intake of animal fat combined with higher fiber altered lipid metabolism in the rumen and peripheral circulation and contributed to changes in fat content and fatty acid composition in goat milk. Top of PagePerformance of dairy goats fed isonitrogenous diets containing soybean meal or hydrolyzed feather meal during early lactation Lactating dairy goats were utilized in a 105-day continuous feeding experiment to compare hydrolyzed feather meal with soybean meal as a protein supplement for milk production. Treatments were isonitrogenous and isoenergetic diets containing soybean meal or hydrolyzed feather meal. Fifty percent of total dietary nitrogen was provided by test proteins. Ruminal ammonia nitrogen (16.1 vs 4.7 mg/dL) and total volatile fatty acids (79.5 vs 69.6 mM) were lower in goats fed hydrolyzed feather meal. Dry matter intake (2.90 vs 2.52 kg/day), live body weight (48.1 vs 47.7 kg), and milk yield (3.20 vs 3.16 kg/day) were similar between treatments. Milk protein content and yield, true protein N, and casein N were lower in goats fed hydrolyzed feather meal. Serum total protein and urea N were lower in goats fed hydrolyzed feather meal while plasma glucose was similar between treatments. Feed efficiency (kg 4% fat-corrected milk/kg dry matter) was slightly higher in goats fed hydrolyzed feather meal and no differences were observed in energy and protein efficiencies. Limitation in microbial protein synthesis due to suboptimal NH3-N concentration in the rumen and quality of protein available for intestinal absorption may be important in the utilization of hydrolyzed feather meal for milk production. Top of PageInfluence of forage-to-concentrate ratios on intake, digestibility, chewing, and milk production of dairy goats Lactating Saanen × Marota dairy goats in a 3 × 3 Latin square designed
exerpiment were studied for the effects of forage-to-concentrate ratios on
intake, digestibility, chewing activities, milk production, and contents.
Treatments were isonitrogenous diets of Cunha (Clitoria ternatea)
silage and cassava (Manihot esculenta) meal with forage-to-concentrate
ratios of 75:25, 60:40, or 45:55, respectively. Intake of dry matter (g/day and
g/kg BW0.75) increased with a decrease in forage-to-concentrate
ratio. Digestibility of dry matter increased while that of neutral detergent
fiber decreased as forage-to-concentrate ratio decreased. Chewing efficiency
(min/g NDF per kg BW0.75) decreased as forage-to-concentrate ratio
decreased. Milk production was not affected by the forage-to-concentrate
ratios. Milk fat contents (%) were 3.6, 3.3, and 2.9 for forage-to-concentrate
ratios 75:25, 60:40, and 45:55, respectively. Body weight changes appeared to
be negatively correlated to forage-to-concentrate ratios. Effect of source and amount of
protein on milk production in dairy goats 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 solids-non-fat (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%), ß-hydroxybutyrate (843 M), plasma
glucose (68.8 mg/dL), NEFA (600 eq/dL), and plasma total protein (74.5 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. Dietary fiber and milk yield, mastication, digestion, and rate of passage in goats fed alfalfa hay Two experiments were conducted to study the effect of intake of fiber on productive performance of high producing dairy goats during early to midlactation. Four dietary treatments were isonitrogenous and consisted of combinations of chopped alfalfa hay and concentrate, yielding 14, 18, 22, and 26% ADF. In Experiment 1, 40 multiparous Alpine does were used in a completely randomized block design. Milk fat content and total chewing time increased, and milk yield tended to decrease, as dietary ADF intake increased. Chewing efficiency [min/(g × kg BW0.75)] for DM decreased, whereas that for ADF increased as ADF intake increased. Prediction equations were the following: milk fat yield, g/d = 115.78 - 0.128 × ADF intake, g/d + 0.00021 × (ADF intake)2 (R = 0.55); total chewing time, min/d = 345.33 + 0.32 × ADF intake, g/d (R = 0.60). In Experiment 2, 20 does were used in a completely randomized design. Apparent digestibilities of DM and energy decreased as dietary ADF intake increased. Rumen turnover rate and transit time of liquid were affected by ADF intake. Transit time of hay decreased as ADF intake increased. Intake of ADF affected pH and ammonia, acetate, and butyrate concentrations in the rumen. Acetate to propionate ratio increased with ADF intake. No apparent trends were observed in whole blood ß-hydroxybutyrate or in plasma NEFA concentrations related to ADF intake. It appeared that DMI and milk fat yield leveled at 22% ADF or 43% NDF. For lactating dairy goats producing more than 3.5 kg/d of milk, calculated fat output reached a plateau when they consumed 587 g/d of ADF and spent 512 min/d chewing. Top of PageInfluence of dietary protein on performance of dairy goats during pregnancy An experiment was conducted utilizing 44 Alpine does (48 kg of BW) to examine the effects of dietary protein intake on nutritional status and performance of does during the latter half of pregnancy and parturition. All dry does were bred, confirmed pregnant, and fed a diet contianing 9% CP and 2.04 Mcal of metabolizable energy/kg of DM through wk 11 of gestation. On wk 12, does were blocked by BW and assigned to one of three dietary treatments: 8.8% (low) CP, 11.0% (medium) CP, and 14.3% (high) CP. All diets were isocaloric (2.04 Mcal of metabolizable energy/kg of DM) and fed for ad libitum intake from wk 12 of gestation until parturition. Average CP intakes for low, medium, and high protein were 164, 220, and 303 g/d, respectively. Body weight gains increased with increasing CP intake. Kidding rates were 79, 100, and 93% for the low, medium, and high protein groups. Gestation length, litter size, and litter weight did not differ among treatment groups. Urea N in jugular blood plasma increased with increasing CP intake. Plasma glucose and whole blood ß-hydroxybutyrate tended to increase with increasing CP intake. Plasma glucose decreased 7, 6, and 3%, and NEFA increased 97, 400, and 187% between wk 13 and 21 of gestation for the low, medium, and high protein diets, respectively. The data suggest that the low protein diet may be inadequate to meet the does' protein requirement during late gestation, but there was no apparent advantage in feeding the high rather than the medium protein diet. Intake of CP for the medium protein diet, 9.8 g/kg of BW0.75, w Top of Page |
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