Reproductive traits in breeding herds can be improved through crossbreeding, which results in breed differences, heterosis and breed complementarity. The aim of this study was to estimate group additive genetic and dominance effects for three reproductive traits; probability of artificial insemination (AIP); calving success (CS); and days to calving (DC) for Hereford (H), Angus (A), Nellore (N) and Salers (S) breeds under grazing conditions. Data were obtained from an experiment carried out during 1992-2002 by the

Selection has emphasized animal growth, leading to an increase in their mature size affecting in some cases the pregnancy of the cows and the efficiency of the systems. Usually, crossbreeding improve productivity because of the genetic effects that the cows exploit, but the impact on mature weight (MW) has not been studied. The present study aimed at estimating MW and genetic parameters associated with the MW in crosses between two British breeds: Hereford (H/H) and Angus (A/A), a Continental: Salers (S/S), and a Zebu: Nelore (N/N). MW was analyzed at 4; 4.5; 5; 5.5 and 6 years of age using a repeated-measure sire model. For parameters estimation, an additive – dominant model was used including the fixed effects of breed group, contemporary group, and age as covariate linear and quadratic, with the linear regression fitted by breed group. Permanent environmental and sire were included as random effects. According to the results, it is expected to observe heterosis between H/H and N/N, however, the structure of the data may not be enough for estimate accurately the genetic parameters in this trait. The A/H, N/H, S/H, S/SH and H/NH cows were heavier than the H/H cows. All the breed groups continue gaining weight until six years of age. The results revealed that British crossbred animals are heavier than H/H at the first crossing but not in the following. Crossbred cows with proportions of 0.5 and greater for the Continental breed are heavier than H/H cows. Crosses between British and Zebu cows have higher mature weight than H/H at the first crossing and in backcrosses toward the British in all ages.

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Genetic evaluations are an efficient tool to select sires, and for them it is necessary to have identification of environmental effects, genetic parameters, and acceptable degree of connectedness between herds. Evaluation of Limousin breed genetics has been developing since 2012. The objectives were to determine the most relevant fixed environmental effects of the characteristics in the genetic evaluation and to estimate the degree of connectedness between herds. The productive and genealogical records were extracted from the Limousin genetic evaluation database of the National Institute of Agricultural Research. Objective measurements were available for the characteristics birth weight (916 records), weaning (818), 18 months (438), ribeye area (435), and 12th-13th rib fat thickness (435) for 2012, 2013, 2014, 2015 and 2016 corresponding to four herds. The results showed that the fixed environmental effects considered presented a significant value (p<0.05), and that herds were connected to each other with average values of prediction error variance (pevd), and connectedness rating (cr) of 113.9 and 7.9, respectively. Concluding that the most relevant fixed environmental effects were year, sex, herd, age at weaning and age at 18 months, and that herds were connected with a low connectedness degree.

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