Effects of stage of lactation and dietary forage level on body composition of Alpine dairy goats.

Multiparous Alpine does (42) were used to determine how stage of lactation and dietary forage level affect body composition. The feeding and body composition portion of the study had a 2 x 3 factorial arrangement of treatments. Eighteen does were fed a 40% forage diet (40F) and 18 received a diet with 60% forage (60F) for approximately 2, 4, or 6 mo of lactation (59 +/- 1.3, 116 +/- 1.0, and 184 +/- 1.4 d, respectively), followed by determination of body composition (6 does per diet at each time of slaughter). Does were assigned sequentially to treatments as kidding occurred. The 60F diet had 20% more dehydrated alfalfa pellets than the 40F diet, with higher levels of corn and soybean meal and inclusion of supplemental fat in the 40F diet. Initial body composition measures were made with 6 other does a few days after kidding (0 mo; 4 +/- 0.6 d). Before parturition, does were fed a 50% concentrate diet free choice. Intake of dry matter was greater for 60F than for 40F, average daily gain tended to be affected by an interaction between diet and month (0, 24, 121, -61, 46, and 73 g), and 4% fat-corrected milk was less in mo 5 to 6 than earlier. Internal fat mass was greatest among times at 6 mo and greater for 40F than for 60F. Mass of the gastrointestinal tract was less for 40F than for 60F and decreased with increasing time in lactation. Concentrations of fat in the carcass (13.8, 13.1, 16.5, 11.2, 11.5, and 14.4%), noncarcass tissues (18.6, 24.2, 33.3, 14.3, 16.5, and 24.5%), and empty body (16.5, 18.7, 25.2, 12.9, 14.1, and 19.5% for 40F at 2 mo, 40F at 4 mo, 40F at 6 mo, 60F at 2 mo, 60F at 4 mo, and 60F at 6 mo, respectively) were affected by stage of lactation and diet. Based on daily change in tissue mass and energy, energy concentration in tissue mobilized or accreted was 16, 20, and 32 MJ/kg in 1 to 2, 3 to 4, and 5 to 6 mo of lactation, respectively. In conclusion, based on tissue mass, more energy was expended by the gastrointestinal tract with 60F than with 40F. Considerable internal fat appeared to be mobilized in early lactation, particularly with the diet moderate to high in forage, with more rapid and a greater magnitude of repletion by does consuming the diet lower in forage. The concentration of energy in tissue mobilized or accreted varied with stage of lactation, being considerably greater at 5 to 6 mo of lactation than earlier.

Effects of breed and diet on growth and body composition of crossbred Boer and Spanish wether goats.

Sixty growing 3/4 Boer x 1/4 Spanish (BS) and Spanish (SP) wethers were used to determine influences of diet and breed on growth and body composition. A pelleted 50% concentrate diet (CD) and a diet based on grass hay (HD) were fed for ad libitum intake. Six wethers of each breed were slaughtered at 0 wk (total of 12). Six wethers of each diet-breed combination were slaughtered at 14 and 28 wk (24 per time) after consumption of the CD or HD. Initial BW of fed wethers were 21.6 and 18.8 kg for BS and SP, respectively (SEM = 0.7). Average daily gain during the entire experiment was influenced by an interaction (P < 0.05) between breed and diet (199, 142, 44, and 50 g/d for BS:CD, SP:CD, BS:HD, and SP:HD, respectively). Carcass mass was greater (P < 0.05) for CD vs. HD (56.2, 56.2, 53.2, and 54.0% of empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively). Mass of the liver (2.11, 1.92, 2.00, and 1.98% of empty BW; SEM = 0.05) and gastrointestinal tract (5.50, 4.83, 8.43, and 8.36% of empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively; SEM = 0.16) tended (P < 0.07) to be influenced by an interaction between breed and diet. Mass of internal fat (12.2, 12.1, 3.4, and 3.4% empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively; SEM = 0.3) differed (P < 0.05) between diets. Energy in the carcass (320, 236, 87, and 79 MJ), noncarcass tissues (318, 237, 77, and 72 MJ), and empty body (638, 472, 164, and 150 MJ) ranked (P < 0.05) BS:CD > SP:CD > BS:HD and SP:HD. Empty body concentration of protein was 18.3, 17.5, 18.3, and 19.7% (SEM = 0.3) and of fat was 24.0, 23.4, 10.8, and 10.3% for BS:CD, SP:CD, BS:HD, and SP:HD, respectively (SEM = 0.6). Energy concentration in accreted tissue was 17.0, 18.7, 16.3, and 6.4 MJ/kg for CD:wk 1 to 14, CD:wk 15 to 28, HD:wk 1 to 14, and HD:wk 15 to 28, respectively (SEM = 1.4). In conclusion, relatively high growth potential of growing Boer crossbred goats with a moderate to high nutritional plane does not entail a penalty in realized growth when the nutritional plane is low. Body composition of growing Boer and Spanish goats is fairly similar regardless of growth rate. For growing meat goats other than with a prolonged limited nutritional plane, an average energy concentration in accreted tissue is 17.3 MJ/kg.

Effect of extended storage on microbiological quality, somatic cell count, and composition of raw goat milk on a farm.

Dairy goat herds in the United States generally are small, widely scattered, and distant from processing facilities. Unlike the situation for cow milk, it is not cost-effective to collect goat milk everyday or every other day. In some areas, goat milk is collected only once each week, which is in violation of regulations specified in the Pasteurized Milk Ordinance for grade A milk. This study was conducted to determine the effect of up to 7 days of refrigerated bulk tank storage on composition, somatic cell count (SCC), pH, and microbiological quality of goat milk. Duplicate farm bulk tank samples were taken daily after the morning milking for seven consecutive days each month during the lactation season. Samples were analyzed immediately for all variables except free fatty acids. There were no significant changes (P > 0.05) detected in milk fat, protein, lactose, nonfat solids, SCC, or pH during extended storage, although significant effects of stage of lactation (P < 0.05) were observed. The mean standard plate count (SPC) increased to 1.8 x 10(5) CFU/ml after 6 days of storage, exceeding the grade A limit (i.e., 1.0 x 10(5) CFU/ml). The mean psychrotrophic bacteria count increased steadily to 1.5 x 10(4) CFU/ml after 6 days of storage, whereas the mean coliform count was approximately 500 CFU/ml for the first 3 days and less than 2500 CFU/ml throughout the 7 days of storage. No significant changes (P > 0.05) in the concentrations of free fatty acids, except for butyric and caprylic acids, were observed during milk storage. When stored under refrigerated and sanitary conditions, goat milk in farm bulk tanks met the grade A criteria for both SPC and SCC during 5 days of storage but was of low quality thereafter because of the growth of psychrotrophic bacteria.

Effects of dietary protein sources on mohair growth and body weight of yearling Angora doelings.

Fifty-one yearling Angora doelings (20+/-0.6kg initial body weight (BW)) were used to determine effects of different dietary protein sources on BW change and mohair growth. Diets consisted of approximately 40% roughage and 18-19% CP (DM basis), of which two-thirds was supplied by corn gluten meal (CG), cottonseed meal (CT), hydrolyzed feather meal (FT) or menhaden fish meal (FI); DM intake was restricted at approximately 0.7kg/day. During the 94-day experiment, fleece-free ADG was greatest (P<0.05) for FI (35, 33, 35 and 50g), whereas greasy fleece weight was greatest (P<0.05) for CG (4.4, 3.6, 3.4 and 3.4kg for CG, CT, FT and FI, respectively). Likewise, mohair growth rate was greatest among treatments (P<0.05) for CG in each of the three 31- or 32-day periods. Ruminal fluid ammonia N concentration was 8, 11, 6 and 13mg/dl (S.E. 1) immediately before feeding; 10, 18, 11 and 23mg/dl (S.E. 2) at 2h after feeding; 8, 15, 10 and 18mg/dl (S.E. 2) at 4h after feeding; and 4, 6, 5 and 8mg/dl (S.E. 1) at 6h after feeding for CG, CT, FT and FI, respectively. Total VFA concentration in ruminal fluid was similar among treatments (P>0.05) at 4 and 6h, but was generally lower for CG and FT than for CT and FI immediately before feeding (29, 33, 26 and 37mM; S.E. 2) and at 2h after feeding (44, 57, 45 and 51mM for CG, CT, FT and FI, respectively; S.E. 3). In conclusion, the different protein supplements had dissimilar effects on ADG (greatest for FI) and mohair growth (greatest for CG). Factors responsible for these results are unclear, and the range of experimental or production conditions under which comparable findings might occur are unknown and deserve further study.

Validation of antibiotic residue tests for dairy goats.

The SNAP test, LacTek test (B-L and CEF), Charm Bacillus sterothermophilus var. calidolactis disk assay (BsDA), and Charm II Tablet Beta-lactam sequential test were validated using antibiotic-fortified and -incurred goat milk following the protocol for test kit validations of the U.S. Food and Drug Administration Center for Veterinary Medicine. SNAP, Charm BsDA, and Charm II Tablet Sequential tests were sensitive and reliable in detecting antibiotic residues in goat milk. All three assays showed greater than 90% sensitivity and specificity at tolerance and detection levels. However, caution should be taken in interpreting test results at detection levels. Because of the high sensitivity of these three tests, false-violative results could be obtained in goat milk containing antibiotic residues below the tolerance level. Goat milk testing positive by these tests must be confirmed using a more sophisticated methodology, such as high-performance liquid chromatography, before the milk is condemned. LacTek B-L test did not detect several antibiotics, including penicillin G, in goat milk at tolerance levels. However, LacTek CEF was excellent in detecting ceftiofur residue in goat milk.

Technical note: tissue residues of mimosine and 2,3-dihydroxypyridine after intravenous infusion in goats.

Sixteen growing Alpine wethers (average BW 35 +/- 2 kg) were assigned to one of four treatments to evaluate tissue retention of the leucaena toxins mimosine (MIM) and 2,3-dihydroxypyridine (2,3-DHP). Treatments were infused i.v. for 2 d and were 1) saline control, 2) MIM (200 mg.kg BW-.75.d-1), 3) 2,3-DHP (200 mg.kg BW-.75.d-1), or 4) MIM (100 mg.kg BW-.75.d-1) + 2,3-DHP (100 mg.kg BW-.75.d-1). Immediately after the infusion, the goats were slaughtered and tissue concentrations of MIM and 2,3-DHP were determined via HPLC. No detectable levels of either toxin were found in spleen, heart, lung, or muscle; however, appreciable amounts of MIM and 2,3-DHP were found in plasma, kidney, and liver samples. Kidney MIM content was greater (P < .01) than that of liver, although liver tended to retain slightly more 2,3-DHP (P > .05). Infusion of MIM resulted in a plasma MIM content of 39 to 54 mumol/L and reduced (P < .01) plasma PHE and LEU. Infusion of 2,3-DHP resulted in a plasma 2,3-DHP content of 9.4 mumol/L and increased plasma THR, ARG, VAL, PHE, ILE, LEU, and LYS concentrations (P < .10). Humans consuming offals from ruminants consuming large amounts of the leguminous forage leucaena may be exposed to appreciable quantities of MIM and 2,3-DHP.