Multibreed comparisons of British cattle. Variation in body weight, growth rate and food intake

Abstract

A multibreed cattle experiment involving 25 British breeds was set up to study genetic variation between breeds and genetic inter-breed relationships for a wide spectrum of traits in order to examine the problems of between-breed testing and selection. The experimental design is described and results on between-breed variation are presented for four traits.All animals were housed indoors and from 12 weeks of age were given a single complete pelleted diet ad libitum through a system of Calan-Broadbent electronic gates. Females were mated to produce one purebred and three crossbred calves, which were reared to slaughter in order to measure the efficiency of the cow-calf unit of production.Results based on a total of 292 animals, with an average of 12 per breed, are presented for body weight, cumulated voluntary food intake, daily weight gain and daily food intake over the age range from 12 to 72 weeks. The 25 breed-mean curves for body weight and cumulated food intake displayed a remarkably uniform pattern of rankings at all ages and the rankings were very similar for both traits.The multibreed design used was effective in estimating between-breed variation as a proportion of total variation for the four traits examined. After approximately 1 year of age, the proportion of variation between breeds was approximately 0·70 for body weight and 0·60 for cumulated voluntary food intake. Changes in these traits could therefore be brought about more effectively by selection between breeds rather than within breeds. For average daily weight gain measured over 12-week intervals, between-breed selection was estimated to be most effective in the period of maximum growth rate between 6 and 9 months of age, when between-breed variation was 0·52 of the total. For average daily food intake, measured over 12-week intervals, between-breed selection was likely to be effective beyond 6 months of age, when the proportion of between-breed variation plateaued at 0·48.At all ages, the coefficient of genetic variation between breeds was approximately 0·14 for body weight and daily gain, and remarkably constant at approximately 0·12 for both daily and cumulated food intake. It is suggested that, for growth and intake traits, the genetic variances within and between breeds remain proportional to each other at all ages.

Comparison of degrees of maturity of rabbit lines selected for different traits

“…Fourth, we used only females to estimate the adult weight, when it is well known that rabbit lines can present sexual dimorphism (Blasco and Gómez, 1993, for lines V; Pascual et al, 2008, in line R). All these issues are common in maturity studies, in which males are a very small proportion of all adult animals and females are in different physiological states (Thiessen et al, 1984;Taylor and Murray, 1987b). We did not consider the different litter size of the lines, as this trait is a property of each line, thus litter size is not corrected when comparing growth of lines, or in meat quality studies.…”

Efficiency of food utilization in traditional and sex-controlled systems of beef production

“…Genetically size-scaled formulae based on the Animal Breeding Research Organisation's (ABRO) multibreed cattle experiment (Thiessen, Hnizdo, Maxwell, Gibson and Taylor, 1984) were used. Let W, F and A represent body weight, cumulated voluntary food intake and mature body weight, respectively.…”

“…The basic equation used to establish nutrient requirements was derived from data in which a single complete diet was offered ad libitum to housed, individually-fed British-type cattle throughout the life cycle (Thiessen et al, 1984). The basic equation used to establish nutrient requirements was derived from data in which a single complete diet was offered ad libitum to housed, individually-fed British-type cattle throughout the life cycle (Thiessen et al, 1984).…”

“…Mean food intake cumulated from birth at u = 0-07 up to degree of maturity, u, as given by equation (2) compared with observed mean values and nutrient requirements derived from MAFF (1975) and NRC (1976) Mean cumulated food intake (ME MJ)/(Akg) t Based on mean food intakes given by Thiessen et al (1984) with A = 550 kg. % Based on mean weights and daily gains given by Thiessen et al (1984) with A = 550 kg.…”

“…Recent studies by Taylor (1977 and1984) suggest that the more offspring a dam has, the less efficient the production unit becomes because cull-cow meat is produced less efficiently the later the dam herself is slaughtered. Thus increased longevity is commonly considered to be an advantage, despite its adverse effect on generation interval.…”