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
In beef cattle, fixed time artificial insemination (FTAI) provides a method to inseminate large numbers of females in a specific time, which result in economical gains due, among others, to a more uniform calf crop. However, FTAI requires frequent manipulation of animals in order to inject hormones and for clinical examination. Consequently, animals seemed stressed in less or higher extent at the time of insemination. This can be a problem because it has been demonstrated that application of an acute stress treatment (electric shock, confinement, restraint and rotation) twice a day during the follicular phase of the oestrous cycle prevents the pre-ovulatory LH surge. This study aimed to evaluate if FTAI efficiency of Nellore cows is affected by the degree of stress observed at time of AI. Nellore cows (n=92) were treated (Day 0) with a progesterone intravaginal devise (Primer®, Tecnopec, São Paulo, Brazil) containing 1 g of progesterone and injected with estradiol benzoate (2mg EB, Estrogin, AUSA, Brazil). Primer was removed on Day 8 (08:00 AM) and administered one injection of cloprostenol (125 mcg, Prolise®, Tecnopec, São Paulo, Brazil). Twenty-four hours later, cows received 2 mg EB and insemination (semen from one sire) was done on the afternoon (14:00 to 16:00 PM) of day 10. At time of FTAI, the stress condition was classified as 1 (low), 2 (moderate) or 3 (high) according
ês.
RESUMO
In beef cattle, fixed time artificial insemination (FTAI) provides a method to inseminate large numbers of females in a specific time, which result in economical gains due, among others, to a more uniform calf crop. However, FTAI requires frequent manipulation of animals in order to inject hormones and for clinical examination. Consequently, animals seemed stressed in less or higher extent at the time of insemination. This can be a problem because it has been demonstrated that application of an acute stress treatment (electric shock, confinement, restraint and rotation) twice a day during the follicular phase of the oestrous cycle prevents the pre-ovulatory LH surge. This study aimed to evaluate if FTAI efficiency of Nellore cows is affected by the degree of stress observed at time of AI. Nellore cows (n=92) were treated (Day 0) with a progesterone intravaginal devise (Primer®, Tecnopec, São Paulo, Brazil) containing 1 g of progesterone and injected with estradiol benzoate (2mg EB, Estrogin, AUSA, Brazil). Primer was removed on Day 8 (08:00 AM) and administered one injection of cloprostenol (125 mcg, Prolise®, Tecnopec, São Paulo, Brazil). Twenty-four hours later, cows received 2 mg EB and insemination (semen from one sire) was done on the afternoon (14:00 to 16:00 PM) of day 10. At time of FTAI, the stress condition was classified as 1 (low), 2 (moderate) or 3 (high) according
ês.
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.