RESUMO
The purpose of this study was to identify genomic regions associated with carcass traits in an experimental Nelore cattle population. The studied data set contained 2,306 ultrasound records for longissimus muscle area (LMA), 1,832 for backfat thickness (BF), and 1,830 for rump fat thickness (RF). A high-density SNP panel (BovineHD BeadChip assay 700k, Illumina Inc., San Diego, CA) was used for genotyping. After genomic data quality control, 437,197 SNPs from 761 animals were available, of which 721 had phenotypes for LMA, 669 for BF, and 718 for RF. The SNP solutions were estimated using a single-step genomic BLUP approach (ssGWAS), which calculated the variance for windows of 50 consecutive SNPs and the regions that accounted for more than 0.5% of the additive genetic variance were used to search for candidate genes. The results indicated that 12, 18, and 15 different windows were associated to LMA, BF, and RF, respectively. Confirming the polygenic nature of the studied traits, 43, 65, and 53 genes were found in those associated windows, respectively for LMA, BF, and RF. Among the candidate genes, some of them, which already had their functions associated with the expression of energy metabolism, were found associated with fat deposition in this study. In addition, ALKBH3 and HSD17B12 genes, which are related in fibroblast death and metabolism of steroids, were found associated with LMA. The results presented here should help to better understand the genetic and physiologic mechanism regulating the muscle tissue deposition and subcutaneous fat cover expression of Zebu animals. The identification of candidate genes should contribute for Zebu breeding programs in order to consider carcass traits as selection criteria in their genetic evaluation.
Assuntos
Composição Corporal/genética , Bovinos/genética , Estudo de Associação Genômica Ampla , Carne/análise , Adaptação Fisiológica/genética , Criação de Animais Domésticos , Animais , Cruzamento , Bovinos/anatomia & histologia , Metabolismo Energético/genética , Estudos de Associação Genética , Herança Multifatorial , Músculos Paraespinais , Polimorfismo de Nucleotídeo Único , Gordura Subcutânea/anatomia & histologia , Clima TropicalRESUMO
The objective of the study was to analyze nonlinear models that best fit the growth of Caracu cows. The experiment was conducted at the Instituto de Zootecnia, Centro APTA Bovinos de Corte, Sertãozinho, SP. Data of weight at birth to 63 months of age, from 500 females of the Caracu breed were used. The mean weight at birth (BW), weaning weight (W7), weight at 26 months (W26) and weight at 63 months (W63) were, respectively, 32 kg, 198 kg, 354 kg and 488 kg, providing an average daily gain (ADG) of 0.241 kg/day. The nonlinear models used were: Brody, Von Bertalanffy, Logistic and Gompertz. All of the models tended to describe accordingly the growth curve of these animals, but, according to the mean square residual and coefficient of determination adopted to select the most appropriate model, Brody showed the best fit. All models presented a high and negative correlation between the A and k parameters, indicating that the most precocious animals are less likely to reach elevated weights at 63 months of age. The effect of year of birth significantly affected (P 0.01) the parameters A and k, concluding that the animal selection based on growth traits favored the increase of mature weight and growth precocity over the generations.
O objetivo do estudo foi analisar os modelos não-lineares que melhores se ajustam ao crescimento de fêmeas da raça Caracu. O experimento foi conduzido no Instituto de Zootecnia, Centro APTA Bovinos de Corte, Sertãozinho, SP. Dados de peso ao nascimento até os 63 meses de idade de 500 fêmeas da raça Caracu foram utilizados. A media de peso ao nascer (PN), peso a desmama (P7), peso aos 26 meses (P26) e peso aos 63 meses (P63) foram, respectivamente, de 32 kg, 198 kg, 354 kg e 488 kg, fornecendo um ganho médio diário (GMD) de 0,241 kg/dia. Os modelos não-lineares utilizados foram: Brody, Von Bentarlanffy, Logístico e Gompertz. Todos os modelos descreveram adequadamente a curva de crescimento destes animais, porém de acordo com o quadrado médio do resíduo e coeficiente de determinação, adotados para escolha do modelo mais apropriado, Brody mostrou o melhor ajuste. Todos os modelos apresentaram alta e negativa correlação entre os parâmetros A e k, indicando que animais mais precoces possuem menor probabilidade de atingir pesos mais elevados aos 63 meses de idade. O efeito de ano de nascimento afetou significativamente (P 0,01) os parâmetros A e k, sugerindo que a seleção dos animais com base em características de crescimento favoreceu o aumento do peso adulto e a precocidade, com o passar das gerações.
RESUMO
The objective of the study was to analyze nonlinear models that best fit the growth of Caracu cows. The experiment was conducted at the Instituto de Zootecnia, Centro APTA Bovinos de Corte, Sertãozinho, SP. Data of weight at birth to 63 months of age, from 500 females of the Caracu breed were used. The mean weight at birth (BW), weaning weight (W7), weight at 26 months (W26) and weight at 63 months (W63) were, respectively, 32 kg, 198 kg, 354 kg and 488 kg, providing an average daily gain (ADG) of 0.241 kg/day. The nonlinear models used were: Brody, Von Bertalanffy, Logistic and Gompertz. All of the models tended to describe accordingly the growth curve of these animals, but, according to the mean square residual and coefficient of determination adopted to select the most appropriate model, Brody showed the best fit. All models presented a high and negative correlation between the A and k parameters, indicating that the most precocious animals are less likely to reach elevated weights at 63 months of age. The effect of year of birth significantly affected (P 0.01) the parameters A and k, concluding that the animal selection based on growth traits favored the increase of mature weight and growth precocity over the generations.
O objetivo do estudo foi analisar os modelos não-lineares que melhores se ajustam ao crescimento de fêmeas da raça Caracu. O experimento foi conduzido no Instituto de Zootecnia, Centro APTA Bovinos de Corte, Sertãozinho, SP. Dados de peso ao nascimento até os 63 meses de idade de 500 fêmeas da raça Caracu foram utilizados. A media de peso ao nascer (PN), peso a desmama (P7), peso aos 26 meses (P26) e peso aos 63 meses (P63) foram, respectivamente, de 32 kg, 198 kg, 354 kg e 488 kg, fornecendo um ganho médio diário (GMD) de 0,241 kg/dia. Os modelos não-lineares utilizados foram: Brody, Von Bentarlanffy, Logístico e Gompertz. Todos os modelos descreveram adequadamente a curva de crescimento destes animais, porém de acordo com o quadrado médio do resíduo e coeficiente de determinação, adotados para escolha do modelo mais apropriado, Brody mostrou o melhor ajuste. Todos os modelos apresentaram alta e negativa correlação entre os parâmetros A e k, indicando que animais mais precoces possuem menor probabilidade de atingir pesos mais elevados aos 63 meses de idade. O efeito de ano de nascimento afetou significativamente (P 0,01) os parâmetros A e k, sugerindo que a seleção dos animais com base em características de crescimento favoreceu o aumento do peso adulto e a precocidade, com o passar das gerações.
RESUMO
The present study aimed to evaluate feed intake and behavior during the efficiency test of Nellore males. Efficiency test was conducted from June to October of 2012, during 119 days. Registers of 85 Nellore males, with initial averages age of 270 ± 23 days and body weight of 239 ± 41 kg were used. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which individual recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI). The first 28 days of test were for adaptation to diet and environment, and the subsequent 91 days were considered as experimental period. Experimental period was divided in three sub periods (28, 28 and 31 days, respectively). Data were analyzed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model period effects (adaptation - 1 and experimental periods - 2, 3 or 4) and animal age as linear covariate. During the adaptation period, low values (P 0.05) were observed of FI, BA and FV (991 ± 40.7 kg/day, 854 ± 33.2 min/day and 1172 ± 49.4 visits/day, respectively) in relation experimental period (1091 ± 18.5 kg/day, 965 ± 15.1 min/day and 1217 ± 22.5 visits/day, respectively). Feeding behavior traits were analyzed in four test periods (Figure 1), and a reduction (P 0.05) in FI (from 1162 ± 39.2 to 984 ± 77.6 kg/day) and BA (from 992 ± 32.1 to 866 ± 63.6 min/day) was observed in the third period. Additionally, FV m
O artigo não apresenta resumo em português.
RESUMO
The direct determination of carcass composition as experimental routine, despite being the most accurate method, is time consuming, laborious and expensive. Indirect methods have been developed to estimate on quick, simple, economical and reliable ways empty body composition of beef cattle. This study was performed with the objective of developing accurate regression equations to predict carcass composition of Nellore animals using 9-10-11th ribs chemical composition and performance measures as independent variables. Sixty-seven non-castrated Nellore bulls were randomly selected for finishing period in two consecutive years (2008 and 2009) and were finished in individual pens for approximately 100 days, until they reached four millimeters of subcutaneous fat thickness over Longissimus muscle. They were slaughtered at 540 days of average age and body weight at slaughter (BW) and carcass weight (CW) were taken. The 9-10-11th ribs cut was obtained according to Hankins and Howe (1946) and weighted (RW). The carcass composition was obtained after grinding, homogenizing, sampling and analyzing the left side of the carcass. Chemical analysis of 9-10-11th ribs cut and carcass were carried for protein (RP and CP), fat (RF and CF), ashes (RA and CA) and water (RWt and CWt). Stepwise and Mallows Cp options were used in PROC GLMSELECT (SAS Inst., Inc., Cary, NC) to determine significant (
O artigo não apresenta resumo em português.
RESUMO
This study aimed to evaluate feed intake and behavior during feed efficiency test of Nellore males from different residual feed intake (RFI) classes. Data from 85 Nellore males, with initial average age of 270 ± 23 days and body weight of 239 ± 41 kg were used. The feed efficiency test was performed during 119 days, divided in four periods. The first period (adaptation) had 28 days, and the three subsequent periods had, respectively, 28, 28 and 31 days. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI) individual data. After test end, RFI was calculated by the difference between observed and predicted feed intake, based on average daily gain and metabolic body weight. Then, animals were classified into low ( mean - 0.5 standard deviation-SD), medium (± 0.5 SD from mean) and high (>mean + 0.5 SD) RFI. Statistical analyzes were performed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model effects of test period (1, 2, 3 or 4), RFI classes (low, medium or high) and interaction, being animal age considered as linear covariate. Feeding behavior pattern was not different among the efficiency test periods (P>0.05), however differences were detected among RFI classes inside the periods (P 0.01) (Figure 1). Low RFI animals, when compared to the medium and high RFI
O artigo não apresenta resumo em português.
RESUMO
This study was carried out to identify associations among carcass traits and residual feed intake (RFI) in young Nellore males feedlot finished. Data was obtained in four experiments, after the animals had been evaluated in individual pens and classified in low RFI( mean - 0.5 standard deviation), medium RFI (± 0.5 standard deviation from mean) and high RFI (> mean + 0.5 standard deviation). One hundred-sixteen non castrated males from low and high RFI classes, with 369 kg of initial body weight and 439 days of initial age, were used for finishing phase. Animals were distributed in individual pens for 100 days and weighed at the beginning and end of experimental period after 16 hours solids fasting. Animals were slaughtered with a minimum of 4 mm for subcutaneous fat thickness over Longissimus muscle between the 12th and 13th ribs. Slaughter was carried out in experimental slaughter houses following the normal procedures of Federal inspection. After slaughter, carcasses were weighed (hot carcass weight) and transferred to chilling room where they were kept at 2C for 24h. Dressing percentage was calculated as the ratio between hot carcass weight and slaughter body weight. After chilling, carcasses right halves were divided into carcass primary cuts: forequarter, hindquarter and spare ribs, which were also weighed. Data were analyzed using the SAS MIXED procedure (SAS Inst
O artigo não apresenta resumo em português.
RESUMO
Recent advances in the field of animal assisted reproduction have allowed faster dissemination of animals with superior genetics. In cattle, the development of some biotechnologies such as the in vitro production (IVP) of embryos optimized the use of oocytes, which represents a great improvement in embryo production world-wide. Therefore, females with high net merit can be multiplied more efficiently to maximize the number of their offspring. The use of ultrasound-guided transvaginal follicle aspiration combined with IVP allowed wide commercial transfer of IVP-embryos with satisfactory pregnancy results. Yet, there are a number of unanswered areas including the level of repeatability and predictability in IVP systems. Thus, the aim of this study was to evaluate the repeatability of some variables related to IVP of bovine embryos from Nellore breed. The study was conducted from 2011 to 2012 using 42 Nellore cows housed at the Centro APTA Bovinos de Corte located in Sertãozinho-SP, Brazil. Donors were kept under the same management throughout the entire experimental period. All animals underwent a total of 25 transvaginal ultrasound-guided follicular aspiration sections. Oocytes were retrieved and handled similarly by Sexing Technologies using semen from 11 sires. Repeatability was evaluated in the following variables: total number of oocytes, embryos and viable oocytes, viable o
O artigo não possui resumo em português.
RESUMO
Feed efficiency is difficult to evaluate because individual feeding are required. An alternative is selecting animals based on traits easier to obtain and genetically favorably correlated with feed efficiency traits. This study aimed to estimate genetic and phenotypic correlations between feed efficiency traits (residual feed intake RFI, feed efficiency FE and residual BW gain RG) with yearling weight (YW), hip height (HH) and girth circumference (GC) in Nellore cattle. Feed efficiency data set consisted of 887 records of DMI, ADG and BW0.75 obtained during performance tests (83 ± 15 d) to calculate RFI (0.005 ± 0.58 kg DM/d), FE (0.14 ± 0.03) and RG (0.00 ± 0.11 kg/d). FE was calculated as ADG and DMI ratio, RFI was estimated as the error of multiple regression of DMI on ADG and BW0.75, and RG was estimated as the error of multiple regression of ADG on DMI and BW0.75. The YW data set consisted of 7,948 records of males (314.45 ± 45.85 kg) and females (282.68 ± 48.19 kg) adjusted to 378 and 550 d of age, respectively. The HH consisted of 6,418 records of males (131.80 ± 5.40 cm) and females (132.51 ± 5.38 cm), and 3,745 records of GC of males (162.56 ± 8.48 cm) and females (167.72 ± 8.08 cm). Pedigree file contained 9,830 animals. Growth traits were analyzed as unit standard deviation of each sex/age. (Co)variance components were estimated through two-trait animal models
O artigo não apresenta resumo em português.
RESUMO
Several factors can influence the recovery of the amount of oocytes for in vitro embryo production (IVEP), including the age of the donor, the time and the frequency at which the animal is collected and climate station year. Another factor is the individual variation of each animal in the number of oocytes and embryos. Thus, the aim of this work was to evaluate the effect of the number of aspirations and the influence of the months of the year in the amount of total and viable oocytes in Nellore cows. The date was collected from January 2011 to December 2012. Non-lactating, cycling Nellore cows (n = 42) of high genetic value were used as oocyte donors. The procedures were carried out in a farm in southeast Brazil (21816S/48582W), located in humid tropical climate. All the donors were maintained on pasture consisting of guinea grass (Panicum maximum and Urochloa brizantha), getting protein mineral supplement energy and water ad libitum daily. The analyzes were performed by proc GLIMMIX of SAS 9.3 (SAS Inst., Inc., Cary, NC). The amount of total oocytes (P=0.16) and viable (P=0.11) did not influenced by the number of aspirations. However, the months of the year have an effect on the amount of total and viable (P 0.0001) oocytes. Probably the production of oocytes did not suffer influences the number of aspirations performed mainly because the intervals between each OPU
O artigo não possui resumo em português.