Twinning Rates for North American Holstein Sires

Abstract

Calving data of North American Holsteins were analyzed using a linear sire model and a threshold sire model to estimate fixed effects and sire predicted transmitting abilities (PTA) for twinning rate. The data were 1,324,678 births of 37,174 sires of cows from the National Association of Animal Breeders (NAAB) calving ease database. All twins were assumed to be dizygotic. Triplets were not included in the analysis. The twinning rate was 5.02%. The sire model included relationships among sires and fixed effects of herd-years, season, parity, and sire groups. Different estimates of heritability due to models and restrictions on data have been demonstrated. Heritability estimates for the sire of the cow effect were 2.10% by the linear model analysis and 8.71% by the threshold model analysis. Sire PTA for twinning rate ranged from 1.6 to 8.0%. Mean incidence of twins increased from first to fifth and later parities: 1.63, 5.22, 6.66, 7.19, and 7.19%, respectively. Some changes with season were also evident. The incidence of twins was highest in April to June, at 5.88%, and lowest in October to December, at 4.23%. Sire group effects showed that sires born after 1990 had a higher incidence of twins than sires born before 1990. The mean twinning rate for sires born before 1980 was 4.55% compared with a mean of 5.58% for sires born after 1991. Characteristics of individual sire evaluations are discussed. Ample opportunity exists to change the incidence of twins in the Holstein population. Sire selection can be used to reduce the incidence of twins and also the increased cost of production associated with twins. From a national perspective, a reduction in the incidence of twin births can result in a saving of as much as $55 million per year.

Prevalence of, and risk factors associated with, perinatal calf mortality in pasture-based Holstein-Friesian cows

“…The higher odds of perinatal mortality in the winter months in this study are in agreement with the results of McGuirk et al (1999), Harbers et al (2000), Johanson et al (2001) and Silva del Rio et al (2007) but are in contrast to the results of Meyer et al (2001), McClintock (2004) and Ansari-Lari (2007). Colder weather is associated with increased gestation length, higher calf birth weight and dystocia (Colburn et al, 1997;McGuirk et al, 1999), all contributory factors to perinatal mortality.…”

Effect of single and multiple pregnancies on performance of primiparous and multiparous cows

“…Studies conducted in Poland indicate that twins account for 1 to 4 % of calves born (Kuźma and Kuźma, 1994;Sawa et al, 2012;Skrzypek et al, 1989). In a North American study of 1.3 million calvings, twin pregnancies accounted for 5 % (Johanson et al, 2001). According to Des Coteaux et al (2010) and López-Gatius and Hunter (2005), twin pregnancies are estimated to form about 10 % of all pregnancies in dairy cattle, but are much less frequent in beef cattle.…”

The environmental impact of recombinant bovine somatotropin (rbST) use in dairy production

“…Previous data indicate that rbST use has no significant impact on culling (49,50); therefore, no adjustment in replacement rate was required. Replacement heifer numbers were modeled based on the aforementioned calving interval, an average age at first calving of 25.5 mo (44), a sex ratio at birth of 49% females (56), a twinning ratio of 5% (57,58), and published heifer mortality rates (44). The resulting index of 0.83 heifers per cow (milking and dry) was estimated by using USDA data (www.ers.usda.gov/publications/ldp) and was in agreement with the value of 0.83 published by DairyMetrics (45).…”