Effect of monitoring corpus luteum function on days open.

The concentration of progesterone in milk fat was measured to ascertain whether knowledge of corpus luteum function could be used to increase reproductive efficiency. As they calved, 47 cows were assigned to either a milk-sampled group (24) or an unsampled control group (23). Progesterone concentrations indicative of a functional corpus luteum were first present at an average of 29.4 days postpartum. The average postpartum interval to first estrus was 49 days for cows sampled and 7.19 days for control cows. The postpartum interval to conception was 84.8 days for sampled cows and 113.7 days for control cows. Twenty of 63 (31.7%) ovulations were not associated with behavioral estrus. Cystic ovarian disease with periods of anestrus were observed in five cows. We conclude that failure to detect estrus was a more limiting factor in reproductive efficiency than was anestrus. To determine the reproductive status after breeding, we measured progesterone concentrations on days 19 through 23 postinsemination. Progesterone was higher for pregnant than for nonpregnant cows on all days. However, only on days 20 and 21 was there complete separation of the progesterone ranges in pregnant and nonpregnant cows.

Decreased reproductive potential and reduced feed consumption in mature white leghorn males fed aflatoxin.

A pair-feeding study was conducted to investigate the relative importance of ingestion of aflatoxin (20 microgram/g diet) versus decreased feed consumption in explaining the effects of dietary aflatoxin on reproduction. Fifty-eight mature White Leghorn males were divided among three groups - control, 0 microgram/g diet ad lib; aflatoxin, 20 micrograms/g diet ad lib; and pair-fed, 0 microgram/g diet pair fed to 20 micrograms/g group. Aflatoxin and pair-fed males consumed significantly less feed than controls during weeks 1 through 5 of the 8-week aflatoxin feeding period. Measures of reproductive potential (semen volume, testes weights, spermatocrit, and plasma testosterone) for pair-fed males were not significantly different from males fed aflatoxin, although both groups were significantly lower than control males. Measures of aflatoxicosis (liver weight, liver fat, and plasma albumin) for pair-fed males were not significantly different from control males, although both groups were significantly different from males fed aflatoxin. In conclusion, decreased feed consumption did not produce symptoms of aflatoxicosis but accounted for 60% of the effects of aflatoxin on reproduction. Therefore, aflatoxin has nutritional and toxicological effects on reproduction.U

Influence of water deprivation on water consumption, growth, and carcass characteristics of ducks.

Two-week-old White Pekin ducks were granted access to water either 4, 6, 8, 16, or 24 hr per day for a period of 4 weeks. The effects of water deprivation on water consumption, growth parameters, and carcass traits were determined. Compared to all other treatments, ducks allowed access to water for 4 hr per day had significantly lower (P less than .05) water intake, body weight, and feed consumption. Increasing water access time to either 6, 8, or 16 hr per day significantly increased (P less than .05) water consumption. Further significant increases in water consumption were not found when ducks were granted access to water for 24 hr per day. Prediction equations are presented for estimating daily intake of water for each treatment. There were no significant differences in final body weight or total feed consumption among ducks on the 6, 8, and 16 hr treatments. Overall feed conversion did not differ significantly among the treatments. No distinct relationship between length of water deprivation and yield of breast meat were observed. The advantages and disadvantages of limiting commercial ducks access to water for 8 hr per day in order to reduce water consumption are discussed.

Effect of dietary aflatoxin on reproductive performance of mature White Leghorn males.

Aflatoxin (20 microgram/g) diet) added to the feed of mature White Leghorn males for five weeks resulted in decreased semen volumes and testes weights and a disruption of the germinal epithelium, but there was no effect on percent fertile eggs or percent hatch of fertile eggs from hens artificially inseminated with spermatozoa from treated males.A significant decrease in feed consumption and body weight preceded the decline in semen volume. White Leghorn males appear to be more susceptible to aflatoxin than broiler breeder males.

Sperm head length as a predictor of fecundity in the sandhill crane, Grus canadensis.

Semen samples from 14 sandhill cranes were collected for 15 weeks. Mean sperm head length which did not vary significantly over weeks was found to be significantly correlated with fertility (P less than 0 . 04; r = 0 . 54, n = 14).