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Title: EFFECT OF FORAGE ENVIRONMENT ON MILK YIELD AND QUALITY IN ANGUS, BRAHMAN, AND RECIPROCAL-CROSS COWS

Author
item Brown, Michael
item BROWN, JR., A. - UNIVERSITY OF ARKANSAS
item Rainosek, Perry
item Miesner, James

Submitted to: Animal Science Progress Report
Publication Type: Experiment Station
Publication Acceptance Date: 6/5/2000
Publication Date: 7/1/2000
Citation: Brown, M.A., Brown, Jr., A.H., Jackson, W.G., Miesner, J.R. 2000. Effect of forage environment on milk yield and quality in Angus, Brahman, and reciprocal-cross cows. Animal Science Progress Report. pp. 53-56.

Interpretive Summary: Endophyte-infected tall fescue (E+) is implicated in losses exceeding $600 million dollars annually for cattle producers in the U.S. Technology to reduce these losses has been only moderately successful. Research at Booneville, AR was conducted to determine if the use of crossbred cows in combination with removal from E+ in the summer would reduce the negative effects of this forage on the milk yield of cows. Results from this research indicated that losses in milk yield could be reduced by removal of cows from E+ in the summer. However, there was no additional advantage to removal from E+ in summer in crossbred cows compared to purebreds. Somatic cell counts were lower in crossbred cows compared to purebreds and Brahman-sired cows had lower SCC compared to Angus-sired cows, indicating potential genetic mechanisms for controlling subclinical mastitis.

Technical Abstract: Milk yield and quality were observed on 93 Angus (AA), Brahman (BB), Angus x Brahman (AB), and Brahman x Angus (BA) cows for three years to evaluate relations of genetic effects to forage environment. Forage environments were common bermudagrass (BG), endophyte-infected tall fescue (E+), and a rotational system of both forages where each forage (BG or E+) was grazed during periods of active growth (ROT). Milk yield (MY) was estimated each of six months (April-September) via milking machine. Milk fat (MF), protein (PRO), and somatic cell count (SCC) were also measured. Hybrid vigor for 24-h MY was similar in each forage, averaging 2.4 kg (P<.01). There was little difference in MY between AB and BA. Sire breed effects for MY were similar among forages and averaged 1.10 kg in favor of BB (P<.10). The only evidence genetic effects for MF was sire breed effects which were similar across forages and averaged .43% in favor of BB (P<.01). .There was little evidence of genetic effects for PRO. Crossbred cows had lower SCC than purebreds on BG (P < .05), E+ (P < .01), and ROT (P > .30). SCC was lower in BA than AB on ROT (P < .10) with a similar trends on BG and E+. Sire breed effects for S+CC were lower in BB on ROT (P < .10) with similar trends on BG and E+. These results suggest that rotation of cows from E+ to BG in the summer can reduce negative effects of E+ on milk yield. The results suggest genetic effects for milk yield and quality were relatively stable across the forage systems evaluated. Conclusions from the research also suggest an advantage to crossbred cows in SCC and provide evidence of genetic breed effects for this trait.