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United States Department of Agriculture

Agricultural Research Service

Title: Genetic Parameters for Growth, Feed Intake, and Feeding Behavior in a Composite Population of Sheep

Authors
item Cammack, K - UNIV. OF NEBRASKA
item Nielsen, M - UNIV. OF NEBRASKA
item Leymaster, Kreg
item Jenkins, Thomas

Submitted to: Journal of Animal Science Supplement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 2001
Publication Date: June 2, 2002
Citation: Cammack, K.M., Nielsen, M.K., Leymaster, K.A., Jenkins, T.G. 2002. Genetic parameters for growth, feed intake, and feeding behavior in a composite population of sheep. Journal of Animal Science. 80(Suppl. 2):44. (Abstract No. 31)

Interpretive Summary: The objective of this study was to estimate genetic parameters for growth, feed intake, and feeding behavior in composite rams (1/2 Columbia, 1/4 Hampshire, 1/4 Suffolk). Data were collected from 1986 to 1997 in Pinpointer units on 1,241 rams from 10 to 17 wk of age. Each Pinpointer unit was an elevated pen with an entrance chute that permitted feeder access for only one ram at a time with disappearance of feed measured electronically. Rams were grouped 11 per pen in 1986 through 1989, and 9 per pen in 1990 through 1997. Data were edited to exclude invalid feeding events. Approximately 80% of the feeding records remained after edits were applied. Estimated direct and maternal heritabilities for initial weight (weight0) were 0.34 and 0.30, respectively. The correlation between direct and maternal genetic effects was -0.88. Average daily gain (ADG) was estimated using three separate sets of data and heritability estimates ranged from 0.27 to 0.29. Results indicated that recording body weight at only the initiation and conclusion of a testing period is sufficient to accurately measure ADG and estimate genetic parameters. Estimated heritability of daily feed intake (DFI) was 0.23. Heritability estimates for number of feeding events per day (NE) and daily feeding time (DT) were 0.33 and 0.24, respectively. Feed efficiency had an estimated heritability of 0.15. Genetic correlations were positive between growth, feed intake, and feeding behavior traits. Phenotypic correlations were generally similar to genetic correlations. Direct genetic correlations were high (0.80) between ADG and DFI; intermediate (0.27 to 0.55) between DFI and DT, DFI and NE, ADG and NE, and NE and DT; and low (0.10 to 0.19) between ADG and weight0, DFI and weight0, and ADG and DT. Results suggest that selection for indices of ADG and DFI will likely change feeding behavior.

Technical Abstract: The objective of this study was to estimate genetic parameters for growth, feed intake, and feeding behavior in composite rams (1/2 Columbia, 1/4 Hampshire, 1/4 Suffolk). Data were collected from 1986 to 1997 in Pinpointer units on 1,241 rams from 10 to 17 wk of age. Each Pinpointer unit was an elevated pen with an entrance chute that permitted feeder access for only one ram at a time with disappearance of feed measured electronically. Rams were grouped 11 per pen in 1986 through 1989, and 9 per pen in 1990 through 1997. Data were edited to exclude invalid feeding events. Approximately 80% of the feeding records remained after edits were applied. Estimated direct and maternal heritabilities for initial weight (weight0) were 0.34 and 0.30, respectively. The correlation between direct and maternal genetic effects was -0.88. Average daily gain (ADG) was estimated using three separate sets of data and heritability estimates ranged from 0.27 to 0.29. Results indicated that recording body weight at only the initiation and conclusion of a testing period is sufficient to accurately measure ADG and estimate genetic parameters. Estimated heritability of daily feed intake (DFI) was 0.23. Heritability estimates for number of feeding events per day (NE) and daily feeding time (DT) were 0.33 and 0.24, respectively. Feed efficiency had an estimated heritability of 0.15. Genetic correlations were positive between growth, feed intake, and feeding behavior traits. Phenotypic correlations were generally similar to genetic correlations. Direct genetic correlations were high (0.80) between ADG and DFI; intermediate (0.27 to 0.55) between DFI and DT, DFI and NE, ADG and NE, and NE and DT; and low (0.10 to 0.19) between ADG and weight0, DFI and weight0, and ADG and DT. Results suggest that selection for indices of ADG and DFI will likely change feeding behavior.

Last Modified: 4/20/2014
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