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Title: EVALUATION OF BIRTH AND WEANING TRAITS OF ROMOSINUANO CALVES AS PRUEBREDS AND CROSSES WITH BRAHMAN AND ANGUS

Author
item Riley, David
item Chase, Chadwick - Chad
item Coleman, Samuel
item OLSON, T. - UNIVERSITY OF FLORIDA

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2006
Publication Date: 1/5/2007
Citation: Riley, D.G., Chase, C.C., Coleman, S.W., Olson, T.A. 2007. Evaluation of birth and weaning traits of romosinuano calves as pruebreds and crosses with brahman and angus. Journal of Animal Science. 85:289-298.

Interpretive Summary: Cattlemen in the South utilize the adaptation attributes of the Brahman breed. However, Brahman purebreds and crossbreds have many limitations; these include reproductive performance as purebreds, temperament issues, and final product (beef) quality, including substandard tenderness. The purpose of this research was to evaluate a Criollo breed, the Romosinuano from South America, to see if purebreds and/or crosses (with Brahman and Angus) provide cattlemen with the necessary adaptation for Southern environments without the Brahman limitations. Bulls from all breeds were mated to all three breeds of cows, producing three purebred groups, and six crossbred groups. Calves (n = 1,347) were born in 2002 through 2005, and weaned in the fall of each year at about 7 mo of age. Traits evaluated included birth and weaning weight, preweaning average daily gain (ADG), body condition score of calves at weaning (BCS; scores ranged from 1 to 9, with higher scores indicating greater amounts of fat cover), and weaning hip height. Romosinuano-Brahman crossbred calves had greater birth weights (7%), weaning weight (9%), ADG (9.7%), BCS (2.7%), and hip height (2.2%) than the average of purebred Romosinuano and Brahman calves. Romosinuano-Angus crossbred calves had greater birth weights (5.1%), weaning weight (7.3%), ADG (7.1%), BCS (1.2%), and hip height (1.7%) than the average of purebred Romosinuano and Angus calves. Brahman-Angus crossbred calves had greater birth weights (11.6%), weaning weight (12.8%), ADG (12.6%), BCS (1.5%), and hip height (3.1%) than the average of purebred Brahman and Angus calves. The effect of Romosinuano in a calf was to reduce birth and weaning weight, ADG, BCS, and hip height; the effect of Brahman on these traits was opposite. However, the effect of Romosinuano in a calf’s dam was to increase values for all of these traits except BCS. A large percentage of Brahman-sired calves out of Angus dams (9%) were born in difficult births and died before 4 d of age. Results indicated that Romosinuano may be used as a source of adaptation to subtropical environments and still obtain superior crossbred performance for weaning traits, although not to the extent of crosses of Brahman and Angus.

Technical Abstract: The objectives of this research were to estimate heterosis and direct and maternal breed effects on birth and weaning traits and to evaluate calving difficulty, calf vigor, and mortality of calves produced in diallels involving Romosinuano, Brahman, and Angus cattle. Romosinuano, Brahman, and Angus bulls were mated to all three breeds of dams, producing three purebred groups, and six F1 groups (reciprocals counted separately). Calves (n = 1,347) were spring-born from 2002 through 2005, and weaned in the fall of each year at about 7 mo of age. Traits evaluated included birth and weaning weight, ADG, BCS, and weaning hip height. Models used to analyze these traits included the fixed effects of year, sire and dam breeds, management unit, calf sex, cow age, and source of Angus sire (within or outside of the research herd). Calf age in days was investigated as a covariate for weaning traits. Sire and dam within sire breed x dam breed combinations were random effects. Estimates of Romosinuano-Brahman and Romosinuano-Angus heterosis (P < 0.05) were 2.3 +/- 0.5 (7.0%) and 1.5 +/- 0.5 kg (5.1%) for birth weight, 19.4 +/- 2.6 (9.0%) and 14.4 +/- 2.6 kg (7.3%) for weaning weight, 78.6 +/- 10.7 (9.7%) and 52.5 +/- 10.4 g (7.1%) for ADG, 0.16 +/- 0.03 (2.7%) and 0.07 +/- 0.03 (1.2%) for BCS, and 2.58 +/- 0.54 cm (2.2%) and 1.8 +/- 0.51 cm (1.7%) for hip height. Heterosis for Brahman-Angus was greater (P < 0.05) than all Romosinuano estimates except for Romosinuano-Brahman ADG, BCS, and hip height, and Romosinuano-Angus BCS. Romosinuano direct effects were negative and lowest of the breeds, except for the Angus estimate for hip height. Romosinuano maternal effects were the largest of the three breeds for birth weight and hip height, but intermediate to the other breeds for weaning weight and ADG. A large proportion of Brahman-sired calves out of Angus dams (0.09 +/- 0.03; n = 11) were born in difficult births and died before 4 d of age. Brahman and Angus purebreds, and Romosinuano-sired calves out of Brahman dams also had large proportions of calves that died before weaning (0.09 or greater). Results indicated that Romosinuano may be used as a source of adaptation to subtropical environments and still incorporate substantial crossbred advantage for weaning traits, although not to the extent of crosses of Brahman and Angus.