Effects of dam and sire group on the propensity for twin calving in cattle

Abstract

Link to this article: http://journals.cambridge.org/abstract_S0003356100012514How to cite this article: C. A. Morris and A. M. Day (1990). Effects of dam and sire group on the propensity for twin calving in cattle. ABSTRACTThe incidence of twin calvings and double ovulations was studied in two Milking Shorthorn herds and one Friesian herd, each with above-average annual twin calving rates (average 0-031, compared with a national rate of 0-01). The proportions of double ovulations were calculated from records comprising 1237 cow x years (cows over 2-0 years of age); means were 0-08, 0-27 and 0-50, for three groups which had previously produced 0, 1 or >1 sets of twins, respectively. All cows (whether still present or no longer in the herd) were then allocated a twin production status, to indicate the number of twin sets (0, 1 or >1) produced, or produced so far, in their lifetime. There were records from 1559 cows, with sire and dam also known. Twin production status was significantly influenced by dam group (P < 0-01), i.e. the twin production status of the cow's dam. Sires were classified into two groups, according to whether any daughters had produced two or more sets of twins. After allowing for ascertainment, sires in the two groups were found to differ (P < 0-01) by 0-06 in the probability of their daughters producing at least one set of twins in their lifetime (i.e. 0-08 to 0-14). One sire and dam combination in particular had prolific daughters with a probability of 0-39 of producing at least one set of twins in their lifetime (compared with a probability of 0-07 for the other extreme combination). The possibility of these observations being explained by the segregation of a single recessive gene was considered, but the necessary interaction between sire group and dam group was not significant.

Environmental effects on ovulation rate in four spring-calving dairy herds with above-average twin calving rate

“…This was consistent with our preliminary findings from two herd years (Morris & Day 1987), but in contrast to resultsfromthe smallercomparison by Labhsetwar et al (1963),whereno relationship was found.…”

“…Inter-calving intervals in the United States 405 of Americawere reportedas 399, 387, and 398 days (Dunbar & Henderson 1953;Everett et al 1966;Nieuwhof et al 1989) compared with 365 days in New Zealand (Macmillan & Moller 1977). Thus, American Holsteins may have higher twin calving rates than New Zealand Friesians (see review by Morris & Day 1986), partly because of the 4-week difference in CCI.…”

“…A preliminary study involving two of the 14 herd years was reported by Morris & Day (1987). Theoretical analyses reported by Dickerson (1978) show that important national increases in beef cow efficiency can be achieved by increasing twin calving rates.…”

Genetic variation in twin calving incidence in herds with a high phenotypic mean

“…This had the effect of roughly halving the true numbers of cows calving per year, and the true numbers of calvings per cow lifetime, but with minimal bias on the genetics of calving singles or twins. We have examined means for TCR, BLT, and NLT from Herds A-C previously, up to their 1987 calvings (Morris & Day 1990), and have now included up to 13 more calving years. Previously, we found evidence of sire and dam genetic effects with no significant interaction, indicating that twinningeffects from both parents could be selected for (or against), although the heritabilities were not estimated at that time.…”

“…It was noticeable that second and third twin calvings contributed to the apparently higher TCR in the (T x T) line in calving years 1995-1997 and 1998-2000, mainly from the five families. Earlier analyses of twin calvings from selected private herds (Morris & Day 1990) identified that elite daughters (sired by elite bulls and out of elite dams) had a mean BLT of 39%. Two of the research-herd families in Table 4, comprising 19 cows, had a mean BLT greater than this, suggesting that they are perhaps candidates for further intense study.…”