Young Dairy Bulls Research Articles

Correlations between Ambient Temperatures Varying from 60°–95° F. and Certain Physiological Responses in Young Dairy Bulls

Correlations between Ambient Temperatures Varying from 60°–95° F. and Certain Physiological Responses in Young Dairy Bulls

Chemical Estimation of Progesterone in the Blood of Cattle, Sheep, and Goats

Summary A method is described for the determination of progesterone in blood based on extraction and partition between organic solvents, paper partition chroma-tography, and ultraviolet absorption spectrophotometry. The hormone was found in a pregnant goat in blood leaving an ovary that contained a corpus luteum and also in that from one containing a Graafian follicle only. It could not be detected in the venous drainage of the uterine horns, gravid and nongravid, in two pregnant goats, nor in the peripheral blood of several of the large domesticated animals. After a single subcutaneous injection of 1 g. progesterone the rate of disappearance from blood was examined. The data suggest a peak concentration about 2 hours after administration. Subcutaneous injection of the hormone for several days resulted in a detectable concentration in the peripheral blood of a pregnant animal. In a young dairy bull plasma progesterone levels above 1 γ/ml were maintained for 24 hours for three consecutive days by daily injections of 1 g. In dairy heifers subcutaneous injections of 100 mg. daily showed maximum levels within 1½ hours and disappearance within 4 hours. When microcrystals were suspended in water, the maximal level attained for plasma progesterone was lower, but measurable amounts were present after 8 hours.

Metabolism of Phosphorus32 and Molybdenum99 in Rats Receiving High Calcium Diets

The syndrome of molybdenum toxicity in animals includes abnormalities which indicate disturbed phosphorus metabo lism. In areas where copper is deficient and molybdenum is excessive in the forage, a condition resembling rickets in young animals and osteomalacia in older animals has been observed. (Britton and Goss, '46; Davis, '50; Cunningham, '50.) Stiffness, broken bones, beaded ribs and enlarged and eroded joints were common. Thomas and Moss ('51) have also observed stiffness, bone involvement and erosion of some joints in young dairy bulls fed molybdenum under experi mental conditions. An abnormality of the front legs and a change in the bone structure of rabbits fed excess molybdenum has been reported. (Arrington and Davis, '53; Lindenstruth, '54.) The results of other experiments which were designed to study phosphorus metabolism in animals receiving molybde num have indicated an alteration of the normal phosphorus metabolism (Comar et al., '49 ; Shirley et al., '50, '51). The sig nificant change in phosphorus metabolism which was observed in steers fed molybdenum was observed to a much less extent in rats (Shirley et al., '51). Subsequent studies with rats and

The Effect of Orally Administered Molybdenum on Growth, Spermatogenesis and Testes Histology of Young Dairy Bulls

Summary Sodium molybdate was fed to two Holstein male calves. In general, the usual symptoms of molybdenum poisoning consisting of mild diarrhea, decreased body weight gains, anemia and greying of the black hair areas were observed. In addition, lameness and joint involvement were found. The most striking and heretofore unnoted symptom was the lack of sexual interest or libido exhibited by these two animals. Ilistological examination of the testes showed marked damage to interstitial cells and germinal epithelium with little or no sperma-togenesis present. Further investigations of these effects and the possibility of using molybdenum as a tool in experiments involving the testes and its products are indicated.

Observations on Vitamin A Deficiency in Young Dairy Bulls

Summary 1.The effects of varying levels of vitamin A on the reproductive development of 13 Holstein, 4 Jersey, and 3 Guernsey bulls were studied. 2.Complete blindness developed in bulls receiving 2,000 I.U. of vitamin A daily. Following supplementation of the ration with 4,000 and 6,000 I.U. of vitamin A daily, very slight spermatogenesis was observed; only moderate sperm production was found following 5 months of therapy with 100,000 I.U. of vitamin A daily. 3.Bulls which received 4,000 and 6,000 I.U. daily of vitamin A until 300lb. in weight, and then 8 and 16 I.U. daily per lb. of body weight, exhibited convulsions, showed evidence of night blindness, and three became totally blind. Sexual maturity was delayed, sex drive inhibited, and spermatogenesis limited. Cystic pituitary glands were observed in all bulls except the controls. Histological differences were observed, however, in both the anterior pituitary glands and the adrenal glands of the bulls. 4.Although moderate prepubertal vitamin A deficiency did not completely inhibit sperm production, fertility and reproductive capacity appeared to be seriously impaired, since sexual drive and spermatogenesis as measured by laboratory procedures and histological examination were reduced. The possibility that prepubertal damage may be permanent, especially when cystic pituitaries develop or total blindness occurs, should not be overlooked.