Effects of Various Postpartum Treatments upon the Reproductive Efficiency of Dairy Cows

Phenotypic causes of variation in conception interval

“…Conception interval means ranged from 81 days (Whitmore et al, 1974a) to 158 days (VanDemark and Salisbury, 1950) with an unweighted average of 116 days open. The means of services per conception ranged from 1.65 (Brown et al, 1959) to 2.67 (Pelissier, 1970) with an unweighted average of 1.9 services per conception. First service conception rate varied from 36% (Gwazdauskas et al, 1975) to 62% (Trimberger, 1956) with an unweighted average of 49% conception to first service.…”

“…Including all cows in the calculation of services per conception, or services per cow, increases services per conception 0.2 from 2.1 to 2.3 (Barr, 1975), 1.8 to 2.0 (Morrow et al, 1966) and 1.72 to 1.90 (Trimberger, 1956). Brown et al, 1959Erb et al, 1958Hinze, 1959Kelly and Holman, 1975Moller et al, 1967Morrow, 1970Pelissier, 1970Pelissier, 1972Pou et al, 1953Thatcher and Wilcox, 1973Trimberger, 1956Whitmore et al, 1974a To successfully select females on fertility, it is necessary to find other traits that are highly correlated with fertility and that have higher heritabilities than fertility. Cystic ovaries and retained fetal membranes were associated with reduced fertility (Henricson, 1957;Kelly and Holman, 1975;Marion and Gier, 1968;Menge et al, 1962;Moller et al, 1967;Oxender, 1976;Pelissier, 1972;and Whitmore et al, 1974a).…”

“…Tennant et al (1967) eliminated 6.8% of their records because cows had severe retained placentas or postpartum metritis. Brown et al (1959) fotmd a 22% incidence of dystocia or retained placenta at calving, and observed that some abnormal cows needed no medication to recover. Morrow et al (1966) stated that treatments of cows with retained placentas and metritis were helpful in maintaining satisfactory conception intervals.…”