An evaluation of a new maternal line (LP) of rabbits was carried out. This new line was founded following a scheme similar to that applied in the selection for hyperprolificacy in rabbits or pigs. In this case, the selection criteria were hyperlongevity and an independent culling level near the average for prolificacy. Evaluation was carried out by comparison of the reproductive and longevity performance of the LP line with another maternal line recognized for good reproductive performance and standard longevity (V line). The results indicate that the LP line could be a valuable resource for inclusion in the current 3-way cross schema used in rabbit production, because females showed better survival ability and nearly the same prolificacy as the well-reputed V line. A V doe was 1.3 times more likely to leave the herd than an LP doe, and the probability of the differences in prolificacy between lines being greater than 0 was not extreme (no more than 0.22). Differences in relative performance of the lines were observed across farms for prolificacy, longevity, cumulative production, and fertility; however, based on deviance information criterion results, the data supported the hypothesis of only these differences being generated under a genotype x environment interaction for prolificacy traits. The longer productive life of LP females could partially be understood as an indication of success of the selection procedure during the foundation of this line.

The objectives of this study were to analyse the differences in the genetic determination of functional longevity in five Spanish lines of rabbits and to check how different systematic factors might affect this genetic determination. Four of the lines were maternal (lines A, V, H and LP), these lines were established selecting base generation animals according to different criteria, but in the subsequent generations all of them were selected for litter size at weaning. The other is the paternal line R, this line was constituted by selecting animals with an outstanding daily growth rate. The trait analysed, length of productive life, was the time in days between the date of the first positive pregnancy test and the date of culling or death of a doe. Four models extended from the Cox proportional hazard model were used to analyse data of each line separately and jointly. The complete model (Model 1) included the fixed effect of year-season (YS) combination, positive palpation order (OPP), that is, reproductive cycle, physiological status of the doe (PS) at service and number of kits born alive (NBA) in each kindling as time-dependent factors. The inbreeding coefficient was fitted as a continuous covariate and the animal’s additive genetic effect was also fitted to the model (Model 1). The other models were identical to Model 1 but excluding OPP (Model 2) or PS (Model 3) or NBA (Model 4), which were explored to assess the consequence on additive variance estimates of not correcting for these animal-dependent factors. Estimated effective heritabilities of longevity were 0.07 ± 0.03, 0.03 ± 0.02, 0.14 ± 0.09, 0.05 ± 0.04, 0.02 ± 0.01 and 0.04 ± 0.01 for lines A, V, H, LP, R and for the merged data set, respectively. Removing the PS from the model led to an increase in the estimated additive genetic variance in all lines (0.17 ± 0.05, 0.05 ± 0.03, 0.29 ± 0.19, 0.29 ± 0.20, 0.07 ± 0.04 and 0.05 ± 0.02 for lines A, V, H, LP, R and the merged data set, respectively). The highest hazard of death and/or culling was observed during the first two parities and decreased as the order of parity progressed. Does non-pregnant-non-lactating had the highest risk of death or culling. The does that had zero kits born alive incurred the highest risk, and this risk decreased as the NBA increased. In conclusion, the consideration of longevity as selection criterion for the studied rabbit lines is not recommended.

The objective was to compare growth traits in four maternal lines of rabbits (A, V, H and LP), with the aim of understanding the consequence of the different foundation and selection processes on the growth performance of the lines. The lines are currently in the 43th, 38th, 22th and 8th generations, respectively. Two comparisons were performed. One compared the values of the lines at their foundation, using the complete data set, the full pedigree and a two-trait analysis, including data on the selection criteria, litter size. The other comparisons were done during the last period when all the lines were housed together with the same feeding and management. The numbers of records were 323 208 for weaning weight, and 300 553 for slaughter weight and average daily Gain (from 46 708 l). The pedigree file included 346 638 animals. The second analysis used only the data corresponding to each period, and the analysis was conducted using a one-trait model. The model was the same as that defined for the comparisons at the foundation, but the additive effects were excluded. The H and LP lines showed highest values for all the traits compared. In the last periods, a good agreement was observed between the estimated differences, computed with the complete model and data set, or computed with an incomplete model and only data from the comparison period. At last periods, the differences were smaller than at foundation. The importance of the correlated response in growth after selection for litter size at weaning or the importance of a non-programmed intramating selection for the growth traits can explain the changes since foundation.

A crossbreeding experiment between 4 Spanish maternal lines of rabbits was performed to estimate crossbreeding effects on litter size components. The experiment was designed as a complete diallel cross involving 4 lines selected for litter size at weaning (A, V, H, and LP [L]) and their 12 simple crosses. Does from these 16 genetic groups were distributed among 4 Spanish farms, but only V line was present in all farms, allowing connectivity of the data. A total of 2,015 does in the third, fourth, or fifth gestations were subjected to laparoscopy. The recorded traits were ovulation rate (OR), number of implanted embryos (IE), total born (TB), embryo survival (ES), foetal survival (FS), and prenatal survival (PS). The differences in direct genetic effects, maternal genetic effects, and individual heterosis between the lines were estimated according to Dickerson's model. Line A was significantly inferior to lines V and H, whereas line LP was similar to A line, but for FS and PS, line A showed the best values, followed by line LP. Comparing crossbred groups to line V, significant differences were shown favoring crossbred groups for OR and IE. The crossbred groups presented high implantation rate, but the foetal survival was lower than in V line. Important values for commercial production were presented by some crosses for OR (HV, 1.26 ova), IE (AH, 1.50 embryos; HV, 1.41 embryos), and TB (AH, 0.82 rabbits; HV, 0.78 rabbits). Relevant and significant reciprocal effects were found, especially for OR in all cases except the LV and VL crosses. These differences become nonsignificant in most of the other traits. Regarding direct genetic effects, line A presented lower estimates than the other lines with important values for OR, but the opposite was observed for FS. The maternal effects were significant only for some contrasts in OR and revealed that the LP line was inferior to the others (1.08 ova compared to the A line, 1.23 compared to the H line, and 0.38 compared to the V line). In general, high positive values for heterosis were found in crossbred does for OR and IE. The crosses, where lines A and H were involved, showed significant heterosis. The highest values were obtained by crossing lines A and H (1.18 ova for OR, 1.87 embryos for IE) followed by the cross between lines H and V. Crosses between line LP and the other lines had a negative heterosis for FS and PS.

Heat stress plays a role in livestock production in warm climates. Heat stress conditions impair animal welfare and compromise the productive and reproductive performance of dairy cattle. Under heat stress conditions, dairy cattle modify their behavior. Thus, the assessment of behavior alterations can be an indicator of environmental or physiological anomalies. Moreover, precision livestock farming allows for the individual and constant monitoring of animal behavior, arising as a tool to assess animal welfare. The purpose of this study was to evaluate the effect of heat stress on the behavior of dairy cows using activity sensors. The study was carried out in Tinajeros (Albacete, Spain) during the summer of 2020. Activity sensors were installed in 40 cows registering 6 different behaviors. Environmental conditions (temperature and humidity) were also monitored. Hourly data was calculated for both animal behavior and environmental conditions. Temperature and Heat Index (THI) was calculated for each hour. The accumulated THI during the previous 24 h period was determined for each hour, and the hours were statistically classified in quartiles according to the accumulated THI. Two groups were defined as Q4 for no stress and Q1 for heat stress. The results showed that animal behavior was altered under heat stress conditions. Increasing THI produces an increase in general activity, changes in feeding patterns and a decrease in rumination and resting behaviors, which is detrimental to animal welfare. Daily behavioral patterns were also affected. Under heat stress conditions, a reduction in resting behavior during the warmest hours and in rumination during the night was observed. In conclusion, heat stress affected all behaviors recorded as well as the daily patterns of the cows. Precision livestock farming sensors and the modelling of daily patterns were useful tools for monitoring animal behavior and detecting changes due to heat stress.