Agea Iván, García María de la Luz, Blasco Agustín, Massányi Peter, Capcarová Marcela, Argente María-José
Departamento de Tecnología Agroalimentaria, Escuela Politécnica Superior de Orihuela, Universidad Miguel Hernández de Elche, Ctra. de Beniel km 3.2, 03312 Orihuela, Spain.
Institute for Animal Science and Technology, Universitat Politècnica de València, P.O. Box 22012, 46022 València, Spain.
Animals (Basel). 2020 Dec 21;10(12):2447. doi: 10.3390/ani10122447.
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, = 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.
在兔子中进行了一项关于出生时窝产仔数剩余方差的发散选择实验，持续了12代。窝产仔数的剩余方差被估计为在对年份、季节以及胎次和泌乳状态影响进行预校正后窝产仔数的母兔内方差。这项工作的目的是研究针对从交配到断奶期间体况的窝产仔数剩余变异性选择的相关反应。体况直接与动物的脂肪沉积有关。肾周脂肪是兔子的主要脂肪沉积部位。在第二次交配、分娩、分娩后10天和断奶时，使用个体体重（IBW）和肾周脂肪厚度（PFT）来测量体况。分析了前三胎的窝产仔数。两条品系在交配到分娩期间体况均下降；然而，低产仔数品系在分娩时体况的下降幅度较小，尽管该品系出生时窝产仔数较高（+0.54只仔兔，P = 0.93）。低产仔数品系在分娩到早期泌乳期间体况的增加略高。另一方面，体况影响雌性在第三次交配时的接受性和生育能力，例如，接受交配的雌性比不接受交配的雌性具有更高的IBW和PFT（分别高+129克和+0.28毫米），可育雌性比不育雌性具有更高的IBW和PFT（分别高+82克和+0.28毫米）。总之，被选择用于降低窝产仔数变异性的母兔比被选择用于增加窝产仔数变异性的母兔在应对高能量需求情况（如分娩和泌乳）方面表现更好，这与低产仔数品系中更好的健康和福利状况相符。
