The length of test required to measure liveweight change when testing for feed efficiency in cattle

Abstract

Measuring differences in the efficiency of converting feed to liveweight gains of beef cattle depends on assessments of feed intake and animal growth over a specified period. Previous studies have shown that feed intake can be measured with sufficient precision after 35 days, however, to assess growth rate with acceptable precision, a feeding period of 70 days is required when the cattle are weighed fortnightly. In order to test if more frequent weighing could improve the precision of estimates of liveweight, or reduce the duration of tests, animals were tested in units where an automatic weighing system recorded the liveweight of an animal every time it entered a feeder. Eight groups of beef bulls (171 animals in total) were tested. A random coefficient regression model including a cubic spline for time was used to estimate average daily gain. Evaluation of the residual variance, slope (average daily gain), and its standard error from the models showed that through the use of automated liveweight measurement, the duration of tests could be decreased to 56 days without reducing the precision of estimates of liveweight change. Depending on the precision required, further decreases in testing time could be accommodated.

CELL BIOLOGY SYMPOSIUM: Genetics of feed efficiency in dairy and beef cattle1

“…Archer et al (1997) concluded that a 70-d test period (after acclimatization), with animals weighed at least every 2 wk, was suffi cient for a performance test for feed effi ciency. Kearney et al (2004) reported that using automatic weighing when animals were feeding could be used to reduce the duration of the test period to 56 d without affecting the precision of estimating ADG. Kearney et al (2004) reported that using automatic weighing when animals were feeding could be used to reduce the duration of the test period to 56 d without affecting the precision of estimating ADG.…”

“…Although considerable research has been undertaken on the most appropriate length of the test period to obtain accurate predictions for feed effi ciency in growing animals Kearney et al, 2004;Wang et al, 2006), little research is available in lactating cows. Prendiville et al (2011) and Connor et al (2012), albeit both using limited data sets, reported that RFI measured in middle to late lactation was more strongly phenotypically correlated with RFI averaged across lactation than RFI measured in early lactation.…”

Optimizing feed intake recording and feed efficiency estimation to increase the rate of genetic gain for feed efficiency in beef cattle

“…It has also been recommended to use regression coefficient of regular DMI measurement periods on shortened test to optimize the test length (Kearney et al 2004;Culbertson et al 2015). Regression coefficients show the amount of variation in regular test DMI accounted for by shortened test DMI and the amount of bias there Fig.…”

Efficiency of feed utilisation by livestock — Implications and benefits of genetic improvement

“…Other considerations include the type and quality of feed used, the duration of the test to measure feed intake, the production traits of interest (e.g., average daily gain, ADG), and the accuracy with which each trait is measured. Some of these issues have been investigated by Eissen et al (1999) for pigs and Archer et al (1997), Hebart et al (2004) and Kearney et al (2004) for beef cattle.…”