This study aimed at estimating the heritability of age at first calving and of performance traits included in the selection index and the genetic correlations between age at first calving and these performance traits. Data were extracted from the Conexão Delta G database and only data from herds in which heifers were bred younger than 24 months of age were used, resulting in a file with 331,310 evaluated animals. The following traits were included in the analyses: age at first calving, birth to weaning gain, post-weaning weight gain, visual scores of conformation, precocity, and muscling evaluated at weaning and in yearling heifers. Covariance components were obtained by bi-character analyses between traits. An alternative age at first calving was also taken into account, in which all heifers were used, including those that were mated and did not calve. Covariance components and estimates of the effects included in the model were obtained using the software program DMU. Heritability estimates were 0.11 and 0.13 for age at first calving and alternative age at first calving, 0.38 for birth to weaning gain, and 0.13 for post-weaning weight gain. Visual score estimates ranged between 0.16 and 0.18 at weaning and 0.19 and 0.29 in yearlings. Genetic correlation estimates of the traits were low, but in the desirable direction. Selection for birth to weaning gain and visual scores does not have a negative effect on age at first calving or alternative age at first calving.

RESUMO: A vesiculite é um processo inflamatório das glândulas vesiculares, podendo ser unilateral ou bilateral, que acomete reprodutores. O objetivo do presente trabalho foi avaliar a utilização da ultrassonografia como meio de diagnóstico precoce das alterações das vesículas seminais em touros. O presente trabalho foi realizado no município de Videira, Santa Catarina. Analisou-se um total 42 reprodutores, com média de idade de 15 meses, das raças Aberdeen Angus e Polled Hereford em semi-confinamento. Foi realizado exame clinico do estado geral dos animais e exame andrológico dos reprodutores. As amostras de sêmen para a realização do exame das características físicas do ejaculado foram obtidas por eletroejaculação. Através da palpação retal, realizou-se a avaliação das glândulas vesiculares por ultrassonografia. A análise estatística dos dados foi realizada por meio de análise de variância (ANOVA) para comparação entre médias com nível de significância de 5%. A presença de vesiculite foi observada em 31 animais (73,8%) dos 42 analisados. Dos 31 animais portadores 11 animais (35,5%) apresentaram vesiculite bilateral e 20 apresentaram vesiculite unilateral (64,5%; P<0,05). Animais com perímetro escrotal maior tendem a desenvolver vesiculite unilateral, tal fato pode ser explicado pela precocidade sexual agravado pela sodomia entre os animais. O uso do ultrassom auxilia de forma preventiva a detecção de animais portadores de vesiculite em reprodutores.

The objective of this study was to compare the presence of ovarian activity and pregnancy rates to temperature variation at the vulvar skin measured by infrared thermography (IRT). In addition, we also aimed to evaluate the IRT as a non-invasive method to evaluate animal breeding from fixed timed artificial insemination (FTAI). The study comprises 150 non-lactating beef Braford cows (5/8 Hereford × 3/8 Nellore) aged between 3 and 10 years. Data were collected along the FTAI protocol period during animal management. Animals were subjected to reproductive ultrasound evaluation and thermal images were performed by an infrared camera. Mean skin vulvar temperature (°C) and ovarian structures data were compared using Tukey's t test used as follow-up test to ANOVA. We observed a statistical difference in the mean vulvar skin temperature between animals that had the presence of ovarian follicles (34.2 ± 1.8) compared to no activity (35.4 ± 1.0; P < 0.05). However, vulvar skin temperature were similar between pregnant (34.5 ± 1.5) compared to non-pregnant (34.3 ± 1.9) animals (P > 0.05). In conclusion, the IRT technique was efficient to detect changes on vulvar skin temperature observed during FTAI protocol in Braford cows. Therefore, the use of IRT as an indirectly diagnostic tool to detect ovarian activity seems promising and further studies are required to validate their potential in beef cattle production.

This study was intended to estimate the genetic associations between growth traits and visual scores with possible changes in mature weight (MW) in 397,900 Nellore animals. A bi-character analysis was performed to estimate the (co)variances and genetic parameters for MW, which comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, and WM) and yearling (YC, YP, and YM), birth weight (BW), weight from birth to weaning (WG), weight from weaning to yearling (YG), and final index (FIND). The observed mean MW was 417.6±56.2 kg, and the direct genetic effect mean estimated heritability (h² a1 ) of MW was 0.45. Overall, the BW was 31.0±3.7 kg, and the estimated h² was 0.34. The heritability estimate of the maternal additive genetic component (h² m2 ) of BW was 0.07. We calculated the mean WG to be 144.1±26.3 and estimated the h² a2 as 0.18 and h² m2 as 0.07. The value for h² a YG (0.17) and YW (0.26) were also estimated. The heritability of the weaning WC (0.17), WP (0.19), and WM (0.17) and yearling YC (0.25), YP (0.27), and YM (0.25) were estimated using visual scores. The h² m values for weaning WC, WP, and WM (0.06) with visual scores were estimated. The genetic correlations between body weight (BoW) at YC and WC (0.62) were considered moderately high and positive. In addition, YP (0.18), YM (0.15), WP (0.13), and WM (0.14) were considered moderately low compared with MW. The genetic correlation between BW and FIND (0.38) was considered positive and moderate. The heritability estimation indicates that growth traits, visual scores, and weight of adult cows could be changed by selection. Cows that presented the highest h² a values for live weight responded rapidly to selection based on growth characteristics, visual scores, and FIND and might result in increased final MW.

Mature weight (MW) of cows is related to the costs of their production. Usually, cows with moderate MW are more efficient in challenging environments, such as those available in the production systems in Brazil. In the present study, the selection index comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, WM) yearling (YC, YP and YM), scrotal circumference at yearling (SC), days to gain 160kg from birth to weaning (D160) and 240kg after weaning (D240). This are related to birth weight gain at weaning (WG) and from weaning to yearling (YG). The mature (MW) and birth weight (BW) traits were not considered in the selection index. The aim of this study was to estimate the values for the genetic trends (GT) of some important selection (MW) and economic traits (BW). A bi-character analysis of MW and other characteristics was performed to estimate the (co)variance components and genetic parameters. The GT results obtained for MW were null (0.0065% or 0.02718kg per year) in the period 1990-2007. The GT values were determined for BW (-0.0650% or -0.02017kg), WG (0.0758% or 0.0865kg), YG (0.1051% or 0.11377kg), and MW (0.0393% or 0.11276kg) per year. The visual score values (in score units) were also determined for GTat weaning [WC (0.2310%; 0.00707), WP (0.3624%; 0.3623%),aWM (0.01149; 0.01087)] yearling [YC (0.3256%; 0.00990), YP (0.4795%; 0.01496),YM (0.5041%; 0.01457)] per year. Index-based selection was effective to promote genetic progress in WG, WC, WP, WM, YG, YC, YP, and YM characteristics keeping BW and MW constant.