McNitt J I, Lukefahr S D
Center for Small Farm Research, Southern University, Baton Rouge, LA.
J Anim Sci. 1993 Aug;71(8):1996-2005. doi: 10.2527/1993.7181996x.
Growth records of 4,270 weanling rabbits born between March 1985 and December 1989 were studied to evaluate the effects of breed and month of birth on postweaning growth performance of four medium-sized breeds. Californian (CAL), New Zealand White (NZW), Palomino (PAL), and White Satin (WS). Traits examined were 28-d weaning weight (WW), postweaning gain (GAIN), attainment of 1,600-g market weight by 76 d of age (MKT), and approximate age at 1,600 g (AGE). Least squares models included breed, month of birth, sex, and year of birth as fixed effects and litter within breed by month and by year and the residual as random variables. The NZW had significantly higher GAIN and MKT and lower AGE than the other three breeds. White Satin had the highest WW, followed by CAL, NZW, and PAL. White Satin had higher GAIN and lower AGE than PAL or CAL but did not differ for MKT. Poorer performance was seen during the summer, but the NZW tended to be less affected by the environmental extremes than the other breeds. The effects on GAIN of mean monthly temperature and daylength and the interrelationships of these with estimated milk production and litter size at weaning were evaluated by regression methods for the 2,100 NZW fryers. Temperature and daylength had significant effects on GAIN, with lowest GAIN in the summer, but the individual contributions to the variance were small because of some redundancy when month, temperature, and (or) light were included in the same model. Curvilinear trends were observed that favored GAIN as estimated milk production increased but decreased GAIN as litter size at weaning increased. In the hot, humid climate of southern Louisiana important breed differences were noted. There were also indications that daylength may be an important factor in postweaning fryer performance.
对1985年3月至1989年12月出生的4270只断奶幼兔的生长记录进行了研究，以评估品种和出生月份对四个中型品种断奶后生长性能的影响。这四个品种分别是加利福尼亚兔（CAL）、新西兰白兔（NZW）、帕洛米诺兔（PAL）和白色缎毛兔（WS）。所考察的性状包括28日龄断奶体重（WW）、断奶后增重（GAIN）、76日龄时达到1600克上市体重（MKT）以及达到1600克时的大致年龄（AGE）。最小二乘模型将品种、出生月份、性别和出生年份作为固定效应，将品种内按月份和年份划分的窝别以及残差作为随机变量。与其他三个品种相比，新西兰白兔的GAIN和MKT显著更高，AGE更低。白色缎毛兔的WW最高，其次是加利福尼亚兔、新西兰白兔和帕洛米诺兔。白色缎毛兔的GAIN高于帕洛米诺兔或加利福尼亚兔，AGE低于它们，但在MKT方面没有差异。夏季生长性能较差，但与其他品种相比，新西兰白兔受极端环境的影响较小。通过回归方法对2100只新西兰幼兔评估了月平均温度和日照长度对GAIN的影响以及它们与估计产奶量和断奶时窝仔数的相互关系。温度和日照长度对GAIN有显著影响，夏季GAIN最低，但由于在同一模型中纳入月份、温度和（或）光照时存在一些冗余，它们对方差的个体贡献较小。观察到曲线趋势，即随着估计产奶量增加GAIN升高，但随着断奶时窝仔数增加GAIN降低。在路易斯安那州南部炎热潮湿的气候条件下，注意到了重要的品种差异。也有迹象表明日照长度可能是断奶后幼兔生长性能中的一个重要因素。
