Average daily gain rates determine eye muscle area and rump fat depth of beef heifers

• Main Authors: Fredy Andrey Lopez Gonzalez, Jaime Urdapilleta Tarouco, José Fernando Piva Lobato, Harold Ospina Patino, Adriana Kroef Tarouco, Luis Fernando Batista Pinto, Mateus Pivato, Fernanda Dornelles Feijó
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2019-01-01
• Series: Italian Journal of Animal Science
• Subjects: beef cattle; growth; replacement heifers; rib eye area; subcutaneous fat
• Online Access: http://dx.doi.org/10.1080/1828051X.2018.1466665

In cow-calf beef production systems, the growth and development of replacement heifers deserve special attention because they affect the age at puberty and the onset of reproductive activity. Therefore, the objective of this study was to test if changes in average daily gain (ADG) have an effect on eye muscle area, rump fat depth and back-fat thickness in developing beef heifers. These traits of 42 beef heifers were measured over time. The results of the current study allow inferring that heifers older than 385 days and with high rates of ADG (above 0.950 kg per day) have the greatest impact on longissimus muscle area growth (above 57 cm2). On the other hand, it is observed that younger heifers (less than 230 days old) do not exceed 48 cm2 of the longissimus muscle area, even with ADGs around 1.25 kg. A positive relationship between the rate of ADG and rump fat depth was also evidenced, observing that rump fat depth deposition is influenced by the rate of ADG. The results of the current study show a linear trajectory of rump fat depth, indicating that for every 0.10 kg of ADG during a period exceeding 56 days, an increase of 1.09 mm of rump fat depth occurs. In conclusion, this study illustrates a simple way on how ADG and age affect the body composition traits in beef heifers and shows that changes in average daily gain affect muscle and fat tissue growth, as determined by longissimus muscle area and rump fat depth in growing beef heifers.