RESUMO
In study of more efficient animals for food utilization, it is of great importance to know differences between genders. There are differences between male and female cattle in growing and body composition, mainly those related to the action of sex hormones. This study aimed to evaluate the sex effect on feed efficiency traits in young Nellore animals. Individual feed intake data from eight tests, performed from 2005 to 2012 at Centro APTA Bovinos de Corte-Instituto de Zootecnia-Sertãozinho-SP were utilized. The tests began after weaning, when the animals had, on average, 286 days of age and 229 kg of body weight. The tests duration ranged from 56 to 112 days, depending on the year. Traits analyzed were final body weight (FBW), dry matter intake (DMI), average daily gain (ADG), feed conversion ratio (FCR), feed efficiency ratio (FER), residual feed intake (RFI) and Kleiber ratio (KR). Data were analyzed using the MIXED procedure of SAS. The model included the fixed effect age at the test beginning as linear covariate and the random effects: sex, facilities and year. Least square means were calculated and compared by t test. Males had greater FBW than females, what was expected, due to the action of male hormones which benefits the muscle deposition. Greater means of ADG and DMI were also detected for males, when compared to females, because heavier animals have higher gains and
O artigo não apresenta resumo em português.
RESUMO
In study of more efficient animals for food utilization, it is of great importance to know differences between genders. There are differences between male and female cattle in growing and body composition, mainly those related to the action of sex hormones. This study aimed to evaluate the sex effect on feed efficiency traits in young Nellore animals. Individual feed intake data from eight tests, performed from 2005 to 2012 at Centro APTA Bovinos de Corte-Instituto de Zootecnia-Sertãozinho-SP were utilized. The tests began after weaning, when the animals had, on average, 286 days of age and 229 kg of body weight. The tests duration ranged from 56 to 112 days, depending on the year. Traits analyzed were final body weight (FBW), dry matter intake (DMI), average daily gain (ADG), feed conversion ratio (FCR), feed efficiency ratio (FER), residual feed intake (RFI) and Kleiber ratio (KR). Data were analyzed using the MIXED procedure of SAS. The model included the fixed effect age at the test beginning as linear covariate and the random effects: sex, facilities and year. Least square means were calculated and compared by t test. Males had greater FBW than females, what was expected, due to the action of male hormones which benefits the muscle deposition. Greater means of ADG and DMI were also detected for males, when compared to females, because heavier animals have higher gains and
O artigo não apresenta resumo em português.
RESUMO
Several studies have reported differences between male and female cattle in growing and body composition. The differences occur mainly by hormonal factors, however, there is little information about the relationship between sex and feed efficiency traits in beef cattle. The residual feeding intake (RFI) is a feed efficiency measurement and has been an alternative to improve the profit in beef production system. It is defined as the difference between dry matter intake observed and estimated by regression in function of weight gain and metabolic body weight. More efficient animals have the intake observed smaller than the predicted (low RFI), unlike the less efficient ones have the intake bigger than predicted (high RFI). This study aimed to evaluate the sex effect (male and female) on growing and feeding efficiency traits in young Nellore bulls selected for post weaning weight. Data from males and females Nellore animals obtained during RFI evaluation tests were utilized. The tests were performed at Centro APTA Bovinos de Corte Instituto de Zootecnia - Sertãozinho-SP, between 2005 and 2011. The tests duration ranged from 56 to 112 days, with the adaption period raging from 28 to 56 days, depending of the year. At the tests beginning the animals had, on average, 286 ± 42 days of age. The traits analyzed were initial body weight (IBW), final body weight (FBW), average daily gai
O artigo não apresenta resumo em português.
RESUMO
Several studies have reported differences between male and female cattle in growing and body composition. The differences occur mainly by hormonal factors, however, there is little information about the relationship between sex and feed efficiency traits in beef cattle. The residual feeding intake (RFI) is a feed efficiency measurement and has been an alternative to improve the profit in beef production system. It is defined as the difference between dry matter intake observed and estimated by regression in function of weight gain and metabolic body weight. More efficient animals have the intake observed smaller than the predicted (low RFI), unlike the less efficient ones have the intake bigger than predicted (high RFI). This study aimed to evaluate the sex effect (male and female) on growing and feeding efficiency traits in young Nellore bulls selected for post weaning weight. Data from males and females Nellore animals obtained during RFI evaluation tests were utilized. The tests were performed at Centro APTA Bovinos de Corte Instituto de Zootecnia - Sertãozinho-SP, between 2005 and 2011. The tests duration ranged from 56 to 112 days, with the adaption period raging from 28 to 56 days, depending of the year. At the tests beginning the animals had, on average, 286 ± 42 days of age. The traits analyzed were initial body weight (IBW), final body weight (FBW), average daily gai
O artigo não apresenta resumo em português.