Simple SummaryTwo rabbit lines are divergently selected for increasing or decreasing the variability of litter size at birth. Decreasing the litter size variability produces more resilient females with less sensitivity to diseases, being an indirect selection way to improve environmental sensitivity. The kits’ survival rate at weaning was higher in the homogeneous line. Moreover, this line led to a greater uniformity of the kits’ weight at weaning, although the weight variability at birth was higher, which could be due to a higher lactation capacity of the homogeneous line.AbstractA divergent selection experiment on environmental sensitivity was performed in rabbits. The aim was to estimate the correlated response in kit weight and survival, litter weight, and weight distance from birth to weaning. The weight distance was calculated as the absolute value of the differences between the individual value and the mean value of its litter. The relationship between the probability of survival at 4 d of age, and the weight at birth, was studied. Environmental sensitivity was measured as litter size variability. A total of 2484 kits from 127 does from the low line, and 1916 kits of 114 does from the high line of the 12th generation were weighed. Both of the lines showed similar individual and litter weights at birth and weaning, and a similar survival rate at birth, and at 4 d of age. The survival rate at weaning was higher in the low line (0.67 and 0.62; P = 0.93). The weight distance was higher at birth, but lower at weaning in the low line (47.8 g and 54.1 g; P = 0.98). When the weight at birth was high, the kits had a higher survival rate. In conclusion, selection for environmental sensitivity showed a correlated response in the kits’ survival, and in the homogeneity of litter weight at weaning.

A divergent selection experiment for residual variance of litter size at birth was carried out in rabbits during twelve generations. Residual variance of litter size was estimated as the within-doe variance of litter size after pre-correction for year and season as well as parity and lactation status effects. The aim of this work was to study the correlated response to selection for litter size residual variability in body condition from mating to weaning. Body condition is related directly to an animal’s fat deposits. Perirenal fat is the main fat deposit in rabbits. Individual body weight (IBW) and perirenal fat thickness (PFT) were used to measure body condition at second mating, delivery, 10 days after delivery, and weaning. Litter size of the first three parities was analyzed. Both lines decreased body condition between mating to delivery; however, the decrease in body condition at delivery was lower in the low line, despite this line having higher litter size at birth (+0.54 kits, p = 0.93). The increment of body condition between delivery and early lactation was slightly higher in the low line. On the other hand, body condition affected success of females’ receptivity and fertility at the third mating, e.g., receptive females showed a higher IBW and PFT than unreceptive ones (+129 g and +0.28 mm, respectively), and fertile females had a higher IBW and PFT than unfertile ones (+82 g and +0.28 mm, respectively). In conclusion, the does selected for reducing litter size variability showed a better deal with situations of high-energy demand, such as delivery and lactation, than those selected for increasing litter size variability, which would agree with the better health and welfare condition in the low line.

The objective of this work is the didactic integration of apps that are used in the management of livestock farms in the Degree in Agro-Food and Agro-Environmental Engineering. The academic results indicated that the scores improved by 1.67 points when the apps were included in the teaching. In addition, a questionnaire was carried out for the student, resulting that more than 66% of the students answered "Totally agree" to the sentence "The proposed task has made it easier for me to learn the subject". This was also the response for 33% of the students to the sentences "The use of apps has helped me understand the subject" and "I would recommend the use of apps in other subjects of the subject". The answer "Neither agree nor disagree" was the answer selected by 66% of the students for the sentence "The use of apps has brought me closer to that of the livestock sector". The conclusions of this work are that the introduction of apps in teaching improves the academic performance of the student as they facilitate learning. It would be advisable to use this methodology to other subject.

A divergent selection experiment on environmental sensitivity was performed in rabbits. The aim of this study was to estimate the correlated response in kits’ weight and its survival, and weight distance from birth to weaning. Weight distance was calculated as the absolute values of the differences between the individual value and the mean value of its litter. Also, relationship between probability of survival at 4 d of age and weight at birth was studied. Environmental sensitivity was measured as litter size variability. A total of 2484 kits from 127 does of the low line (selected for reducing litter size variability) and 1916 kits of 114 does of the high line (selected for increasing litter size variability) of the 12th generation were weighed. Bayesian methodology was used to estimate the correlated response to selection, and LOGISTIC procedure of SAS was used to estimate the relationship between weight and probability of survival. Both lines showed similar individual weight at birth and at weaning, and similar survival at birth and at 4 d of age. Survival at weaning was higher in the low line than in the high line (0.67 and 0.62; P= 0.93). Weight distance was higher at birth but lower at weaning in the low line (47.8 g and 54.1 g; P=0.98). Kit’s weight at birth affected its survival. In conclusion, selection for environmental sensitivity showed correlated response in kits survival and in homogeneity of litter weight at weaning.

This unedited manuscript has been accepted for future publication. The manuscript will undergo copyediting, typesetting, and galley review before final publication. Please note that this advanced version may differ from the final version. SHORT COMMUNICATION Asynchrony between in vivo and in vitro rabbit embryos Asincronía entre embriones in vivo e in vitro en conejoAssincronia entre embriões in vivo e in vitro em coelho