|Chase, Chadwick - Chad|
Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Proceedings
Publication Acceptance Date: 2/3/2005
Publication Date: 2/8/2005
Citation: Chase, C.C., Riley, D.G., Olson, T.A., Coleman, S.W. 2005. Evaluation of brahman and tropically adapted bos taurus breeds in the humid subtropics. American Society of Animal Science Southern Section Meeting,Symposium on Tropically Adapted Breeds. Regional Project S-1013. Little Rock, Arkansas, February 4-8, 2005. p 27. Interpretive Summary: It has been long recognized that cattle acclimated to the northern regions of the country often do not perform as well in warmer, more humid climates. Classic studies initiated in the 1960s clearly demonstrated that a Hereford cattle line developed in Miles City, MT did not perform as well in Brooksville, FL as a Hereford line developed in Florida. Similarly, the Montana line outperformed the Florida line when both were in Montana. The researchers concluded that the advantages of local over introduced lines were large enough to be of great economic importance in commercial beef production. Matching cow type to the environment in which she is asked to perform is an important consideration particularly in harsh climates. Environment is more than just location, or weather, but also includes nutrition, disease, and pests. Another study that alludes to the nutrition issue was conducted with Brahman cows of small, medium and large frame size. Weaning rate was considerably lower for large frame size first- and second-parity cows compared to small and medium frame cows. This was due to poor calf survival among large frame size cows (mated to large frame bulls) and to low conception for large framed, second-parity cows. There were little differences in third- and greater-parity cows. Condition score was much easier to maintain in small- and medium frame size young cows. While Brahman (Bos indicus) cattle are undoubtedly adapted to the tropics, there are Bos taurus breeds (same species as English cattle) from South America and Africa that are adapted to the tropics. In crossbreeding studies using Senepol and Hereford, heterosis was observed for preweaning calf performance and feedlot gain. There were no differences among breedtypes for carcass traits (tenderness, yield and quality grade). More recently, Tuli x Angus cows were compared to Senepol x Angus and Brahman x Angus for maternal and reproductive traits. Tuli x Angus cows were comparable to Brahman x Angus cows except for calf weaning weight and some calving difficulty at second parity when mated to Charolais bulls. Efficiency calculated as weaning weight per 1000 lb of cow were similar between the two breed types. Most recent studies have evaluated the Romosinuano, a tropically adapted Bos taurus breed native to Colombia. Romosinuano bulls and heifers reach puberty at relatively young ages similar to Angus. Currently a three-way crossbreeding study is being conducted with all possible combinations of Angus, Romosinuano, and Brahman.
Technical Abstract: Classic studies conducted in the 1960s between Brooksville, Florida and Miles City, Montana clearly established the presence of genotype by environment interactions. Those researchers concluded that the advantages of local over introduced lines were large enough to be of great economic significance in commercial beef production. Matching cow type to the environment in which she is asked to perform is an important consideration particularly in harsh climates. Environment, however, is not simply related to geography or climate but also includes nutrition, disease, and pest prevalence. Brahman cows of small, medium, and large frame sizes were bred to like frame size bulls. Weaning rate was considerably lower for large frame size first-parity and second-parity dams compared to small and medium frame size dams. This was due to poor calf survivability for large frame size first-parity dams and to low conception for large frame size second-parity dams. Weaning rates did not differ among frame sizes in third or greater-parity dams. Although the Brahman is undoubtedly adapted to the tropics there are tropically adapted Bos taurus breeds that may offer other attributes for southern US cattle production. In crossbreeding studies between Senepol and Hereford, significant levels of heterosis were observed for preweaning calf performance and feedlot performance of steers. Breedtypes did not differ for USDA yield and quality grades or Warner Bratzler shear force. A more recent study evaluated maternal and reproductive performance of Brahman x Angus, Senepol x Angus, and Tuli x Angus cows. Tuli x Angus cows had similar calf crop born and weaned as Brahman x Angus cows. Reproductive and maternal performance of Tuli x Angus cows were comparable to Brahman x Angus cows except for calf weaning weight and some calving difficulty. Most recent studies have evaluated the Romosinuano, a tropically adapted Bos taurus breed native to Colombia. Earlier studies showed that Romosinuano bulls and heifers reach puberty at relatively young ages similar to Angus. Currently a diallel breeding scheme among Angus, Brahman, and Romosinuano is being conducted.