Abstract
The study was undertaken to investigate the validity of milk urea concentration as an index of the reproductive performances in crossbred Karan-Fries (Holstein FriesianxTharparkar) cows under farm condition. Milk urea wasanalysed in noon milk samples (1200 to 1300 h) to interrelate with the interval from parturition to first service, number of insemination per conception, first service conception rate and service period. Milk progesterone (P4) was analysed in noon milk samples on the day 1, 10, 20 and 30 post insemination to study the effect of milk urea concentration on early embryonic mortality. The interval from parturition to first service was found significantly (p<0.01) higher (77.2′5.5 days) when milk urea concentration was ≥63.4 mg/dl. The average milk urea concentrations (mg/dl) were found 42.1′2.5, 47.9′1.5 and 50.3′3.1, respectively in cows that conceived at 1 s t , 2 n d and 3 r d insemination. However, the variation was not statistically significant. The first insemination conception rate was found significantly (p<0.05) higher (68.8%) when milk urea level was ≤32.4 mg/dl. The service period was found significantly (p<0.05) higher (125.4′8.8 days) when milk urea concentration was ≥45.1 mg/dl. The milk P4 level indicated that the cows, those were detected as non-pregnant on day 60 post insemination were initially pregnant but the pregnancy was terminated sometime during the day 30 to 60 post insemination. The study indicates that the milk urea values may be used as an index of reproductive performances in dairy herd when individual animals are not being monitored for nutritional status. The altered milk urea values may be utilised by the farmers as ready reference to rectify the protein and energy nutrition in cows to achieve the better reproductive performances in herd.
Highlights
Fertility is often associated with the nutritional status
Collection of samples and data Noon (1200 to 1300 h) milk samples were collected from the cows on 1st and 3rd day of each insemination to study the relationship between milk urea concentration and conception rate at different insemination
To study the variations in milk urea and milk P4 concentrations on different post insemination days in pregnant and nonpregnant cows the data were subjected to ANOVA using general linear model procedure of SPSS (SPSS 10.0.1., 1999)
Summary
Fertility is often associated with the nutritional status. The effect of protein nutrition on fertility appears complex. Several mechanisms of protein effects on fertility have been described (Ferguson and Chalupa, 1989) These include impairment of gonadal activities by toxic products of nitrogen metabolism from rumen, altered function of hypothalamo–pituitary-ovarian axis by nitrogen byproducts or altered protein to energy ratio. In dairy cows the excess dietary protein increases blood urea level, alters uterine fluid composition, decreases uterine pH and reduces conception rates (Jordan et al, 1983; Elrod and Butler, 1993; Elrod et al, 1993). Earlier report indicates the possibility of using milk protein content and urea concentration in either blood or milk to monitor the dietary energy and protein intake in dairy cows (Hwang et al, 2000). The present investigation was conducted to interrelate the milk urea concentration with different reproductive parameters in crossbred Karan-Fries cows to validate its utility as an index of reproductive performances under farm condition
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