RESUMO
The objective of this study was to estimate heritability of carcass muscle index (MI) in yearling (MIy) and post-yearling (MIp) Nellore cattle. MI is the measure of longissimus muscle area (LMA) expressed in relation to body weight (MI=100×LMA/BW), being an indicative of animal muscularity. The records of LMA, obtained by ultrasound, and body weight (BW) were from the three Nellore herds reared at Centro APTA Bovinos de Corte, Instituto de Zootecnia, Sertãozinho-SP, born between 1999 to 2011, excepting 1998, 2000 and 2003. The measures were collected when the animals were on average 372 ± 26 days (yearling) and 562 ± 33 days (post-yearling) of age. The animals are progeny of 163 bulls and relationship matrix included 3436 animals. Variance components were estimated by REML in two single-trait analyses. The model included the fixed effects of contemporary group (herd-year-sex, i=1, , 48), month of birth (j=1, , 3) and dam age (linear and quadratic effects) and animal age at measurement (linear effect), and random effects of animal and residual. The average of LMA and BW were: 48.4 ± 10.7 cm² and 287±59 kg; 50.5 ± 9.2 cm² and 339 ± 64 kg, respectively for yearling and post-yearling. Despite the differences between yearling and post-yearling LMA and BW (plus 2.2 cm ² and 52 kg at post-yearling than yearling), the same was not observed for MI. BW has increased from yearling to po
O artigo não apresenta resumo em português.
RESUMO
The objective of this study was to estimate heritability of carcass muscle index (MI) in yearling (MIy) and post-yearling (MIp) Nellore cattle. MI is the measure of longissimus muscle area (LMA) expressed in relation to body weight (MI=100×LMA/BW), being an indicative of animal muscularity. The records of LMA, obtained by ultrasound, and body weight (BW) were from the three Nellore herds reared at Centro APTA Bovinos de Corte, Instituto de Zootecnia, Sertãozinho-SP, born between 1999 to 2011, excepting 1998, 2000 and 2003. The measures were collected when the animals were on average 372 ± 26 days (yearling) and 562 ± 33 days (post-yearling) of age. The animals are progeny of 163 bulls and relationship matrix included 3436 animals. Variance components were estimated by REML in two single-trait analyses. The model included the fixed effects of contemporary group (herd-year-sex, i=1, , 48), month of birth (j=1, , 3) and dam age (linear and quadratic effects) and animal age at measurement (linear effect), and random effects of animal and residual. The average of LMA and BW were: 48.4 ± 10.7 cm² and 287±59 kg; 50.5 ± 9.2 cm² and 339 ± 64 kg, respectively for yearling and post-yearling. Despite the differences between yearling and post-yearling LMA and BW (plus 2.2 cm ² and 52 kg at post-yearling than yearling), the same was not observed for MI. BW has increased from yearling to po
O artigo não apresenta resumo em português.
RESUMO
Residual feed intake (RFI) is a feed efficiency trait defined as the difference between actual feed intake and the one predicted on the basis of requirements for production and maintenance of body weight. Evidence exists of a positive correlation between RFI and fat thickness in Bos taurus, suggesting that low RFI cattle (feed efficient ones) are leaner. The objective of this study was to access the relationship between fat thickness and RFI by partial correlation including all animals (n=603, 300 bulls and 303 heifers), and by means comparison including only animals divergently classified by RFI (low RFI, n=192 and high RFI, n=186). The animals were born from 2004 to 2010, and were performance tested after weaning for 56 to 112 days, depending of test year and sex. The average age and body weight at the beginning of performance test were 286±42 days and 225±51kg. At the end of performance test images of backfat thickness (BF) were obtained by ultrasound (Pie Medical-Aquila-3.5 MHz linear probe) between the 12th and 13th ribs, transversely over the longissimus muscle. Images of rump fat thickness (RF) were obtained at the junction of the gluteus medius and biceps femoris muscles between the hook and pin bones. The images were saved and subsequently analyzed using Echo Image Viewer 1.0. For partial correlations (MANOVA, SAS 9.3), the model included fixed effect of contemporary g
O artigo não apresenta resumo em português.
RESUMO
Residual feed intake (RFI) is a feed efficiency trait defined as the difference between actual feed intake and the one predicted on the basis of requirements for production and maintenance of body weight. Evidence exists of a positive correlation between RFI and fat thickness in Bos taurus, suggesting that low RFI cattle (feed efficient ones) are leaner. The objective of this study was to access the relationship between fat thickness and RFI by partial correlation including all animals (n=603, 300 bulls and 303 heifers), and by means comparison including only animals divergently classified by RFI (low RFI, n=192 and high RFI, n=186). The animals were born from 2004 to 2010, and were performance tested after weaning for 56 to 112 days, depending of test year and sex. The average age and body weight at the beginning of performance test were 286±42 days and 225±51kg. At the end of performance test images of backfat thickness (BF) were obtained by ultrasound (Pie Medical-Aquila-3.5 MHz linear probe) between the 12th and 13th ribs, transversely over the longissimus muscle. Images of rump fat thickness (RF) were obtained at the junction of the gluteus medius and biceps femoris muscles between the hook and pin bones. The images were saved and subsequently analyzed using Echo Image Viewer 1.0. For partial correlations (MANOVA, SAS 9.3), the model included fixed effect of contemporary g
O artigo não apresenta resumo em português.