Call number: LD2668 .T4 1961 C65

Call number: LD2668 .T4 1961 D46

Call number: LD2668 .T4 1961 S56

Call number: LD2668 .T4 1962 E34

Two lactation studies with accompanying digestion trials were conducted to compare the feeding value of Pima cottonseed, with differing degrees of processing, to short staple cottonseed for lactating dairy cows. Additional tests were conducted to examine physical and chemical characteristics of both Pima and short staple cottonseed and the effect of processing on storage characteristics of cottonseeds. Pima cottonseed is higher in CP and ether extract and lower in NDF and ADF than short staple seed. Pima seed has a greater bulk density, a greater proportion of the (-)-gossypol isomer and a lower proportion of the (+)-gossypol compared to short staple cottonseed. In the first lactation study, milk yield was similar across all treatments. Milk fat was higher (P < .05) for finely cracked Pima (x 3.0 mm) and whole Pima diets. Feed efficiency was greatest (P < .05) for the cracked Pima diet. Percentage whole seed passing into the feces of that consumed, was 11% for the whole Pima and 5.2% for the short staple. Total tract digestibility of ADF decreased and that of ether extract increased in cows fed cracked Pima compared to whole Pima or short staple. In the second lactation study, milk yield was higher (P < .05) for cows fed ground Pima (x 2.5 mm), than either whole Pima or coarsely cracked Pima (x 3.5 mm), with short staple intermediate. Feed efficiency (SCM/DMI) was greater for cows fed ground Pima and short staple diets (1.14) than for those fed cracked Pima or whole Pima. Stearic acid was lower, and linoleic and linolenic acids were higher in milk of cows fed ground Pima compared to short staple. Passage of whole seed was two-times greater for cows fed whole Pima compared to whole short staple (12.3% vs. 6.2%), and processing of Pima seed eliminated whole seeds passing in the feces. Ether extract digestibility was lower for the whole Pima compared to the other treatments. Storage of whole, cracked or ground seeds at 32°C and 30% relative humidity for up to 30 d did not cause rancidity or aflatoxin contamination. Storage of processed seeds in covered containers for nine months caused only slight increases in free fatty acid content, and no change in the whole seeds.

Six lactating Holstein cows received ammonia-treated or untreated aflatoxin-contaminated whole cottonseed (AFWC) or pure AFB₁ with their regular ration. Treatments were: AFWC (5,010 ppb AFB₁), 4 kg/day; the same AFWC treated with 1.5% anhydrous ammonia and 10% water; pure AFB₁ (2.2 mg twice daily) given in capsules; same amount AFB₁ treated with 50% NH₄OH for 26 days at 29°C; same amount ammoniated AFB₁ acidified to final pH of 5.0; same treatment as first except concentration of AFB₁ was 5,511 ppb. Levels of aflatoxin M₁ (AFM₁) in milk were monitored before, during, and after each treatment, and conversion and feed-through ratios were calculated. Feed consumption and milk production were also measured. Mutagenicity of acetone extracts of spray-dried milk was determined using Salmonella/microsomal assay. Ammoniation of AFWC did not reduce concentration of AFB₁ to below FDA action level; however, when the seed was fed, the concentration of AFM₁ in milk was less than FDA action level (0.5 μg/L). Ammoniation of AFB₁ was very effective in reducing levels of AFM₁ in milk of treated cows to less than the FDA action level. The average AFB₁/AFM₁ conversion ratios for the steady-state period of AFM₁ excretion in milk while giving AFWC and AFB₁ was 1.06% and 1.18%, respectively. Ammoniation of AFWC reduced the average AFB₁/AFM₁ ratio to 0.20% during the constant-state period of AFM(,1) excretion in milk. The ration containing AFWC (5,010 or 5,511 ppb AFB₁) caused a highly significant decrease in total milk production and feed consumption; ammoniated AFB₁ decreased total milk production significantly. Complete disappearance of AFM₁ from milk after discontinuing Treatments 1-6 was 120, 48, 95, 72, 96, and 120 h, respectively. Under these laboratory conditions, significance of the results of the Ames test was questionable.

An experiment was conducted to study the effect of prolonged nutritional stress on the reproductive performance of twelve Holstein dairy heifers. Energy intake was reduced to 60% NE(m). The animals lost 20% of their body weight during energy restriction (97 days) and gained 29% during the high energy feeding (44 days). Estrous cycles were irregular, delayed, or ceased completely. The conception rate was only 25% during energy reduction. Cycles were reestablished and conception rate improved (67%) during the high energy feeding. Heifers were designated as fertile or infertile according to their success or failure to conceive during the energy reduction period. Serum thyroxine (T₄) levels were slightly decreased (P > .05) while triiodothyronine (T₃) levels were significantly depressed (P < .01) during energy restriction in both fertile and infertile heifers. Serum thyroxine levels were slightly increased (P > .05) in the fertile heifers, but significantly increased (P < .01) in the infertile heifers during high energy feeding. Serum triiodothyronine levels were significantly increased during high energy feeding in both fertile (P < .05) and infertile (P < .01) heifers. Concentrations of blood cortisol were relatively higher in the fertile than in the infertile heifers during the ad libitum and energy restriction periods. This suggests that the fertile heifers possessed elevated adrenal activity that the infertile heifers did not have. Concentrations of blood progesterone of the infertile heifers were severely depressed (P < .01) during the submaintenance feeding while those of the fertile group were not affected (P > .05). Blood glucose levels were significantly reduced during energy reduction and significantly increased during high energy feeding in both groups of heifers (P < .01 for infertile heifers). Blood glucose levels of the infertile heifers at time of insemination (period of energy restriction) were as low as their average levels of the period. Glucose levels of the fertile heifers at time of breeding (period of energy restriction) were greater than their mean concentration during that period and were similar to the mean levels of glucose during the ad libitum period. Low progesterone levels are indicative of ovarian inactivity under such stressful conditions. Adrenal inactivity, (as reflected by low cortisol secretion) and low blood glucose levels at time of insemination of the infertile heifers are probably associated with infertility during submaintenance feeding in dairy heifers.

No description available.

No description available.

No description available.