Interaction of breed type and endophyte-infected tall fescue on milk production and quality in beef cattle

摘要: Decreased milk production of beef cattle grazing endophyte-infected (EI) tall fescue (TF), an important cool season grass in the southeastern United States, can affect calf growth. The objective was to determine whether a thermal or heat-tolerant Bos taurus breed cattle, Romosinuano (RO), would tolerate EI TF toxins relative Angus (AN) cattle. Milk and quality were examined on AN RO cows endophyte-free (EF; variety K-31; n = 36) (variety 37) along with growth their Charolais-sired calves 2007 2008 west central Arkansas. Cows calved between early February late March (spring). yield quality, BW, rectal temperature, serum prolactin determined at 57.1 +/- 2.6 d postpartum every 28 thereafter April August. greater compared (P 0.88). Percent fat EF April, but for July (forage x month, P < 0.001). than protein 0.001) somatic cell counts (log-transformed; less cows. lactose June through August (breed 0.004). Adjusted weaning BW similar 2007, from year, 0.03). Rectal temperature TF, most months month Serum reduced both breeds years greatest (breed, 0.001; forage These data suggest that more thermal-tolerant, still susceptible as shown by reduction concentrations prolactin. However, not influenced previously observed, percent decreased lactation this group different during period observed.