Jean-Marie Bienfait

The relationship between carcass characteristics, plasma hormones and metabolites in young fattening bulls.

Six Belgian Blue bulls (double-muscled type) and six Friesian bulls were offered a fattening diet for 34 weeks. Plasma samples were obtained once a week and also every 20 min over a 24 h period, 7 weeks before slaughter.No differences were observed between the breeds in plasma glucose, urea and free amino nitrogen concentrations, while creatinine was significantly higher in the Belgian Blue bulls. Tri-iodothyronin, tetra-iodothyronin, insulin-like growth factor 1, insulin and testosterone concentrations were higher in the Holstein group. In contrast, the Belgian Blue bulls appeared to produce more growth hormone. The slaughter weight, carcass weight, dressing percentage and proportion of lean meat were significantly higher in the Belgian Blue group. The characteristics of muscle mass (carcass weight, dressing percentage and proportion of lean meat) were positively correlated with creatinine and with the total peak area or peak amplitude of growth hormone. The insulin concentration was positively correlated with the proportion of adipose tissue in the carcass and negatively correlated with the proportion of muscle. There were no correlations between the carcass characteristics and insulin-like growth factor 1 or testosterone. No further information was provided when the ratios of the hormones were correlated with carcass characteristics.

Effects of dietary carbohydrate composition on rumen fermentation, plasma hormones and metabolites in growing-fattening bulls.

Two groups of six bulls were offered a fattening diet based on barley or sugar-beet pulp in the proportions of either 500: 200 g/kg or 200: 500 g/kg to compare the effects of starch and degradable fibre on rumen fermentations, plasma hormones and metabolites. The bulls were fed twice daily at 08.00 and 16.00 h. The large proportion of sugar-beet pulp in the diet induced higher levels of acetic and butyric acids and less propionic acid than the high proportion of barley. The diurnal patterns over a 24-h period of rumen pH, volatile fatty acids, glucose and ammonia were characterized by two cycles. Sugar-beet pulp in large proportions induced more even fermentations as indicated by flatter curves with less extreme values than those produced by a large inclusion of barley in the diet. Ammonia concentration was high before feeding and decreased subsequently during 4 to 6 h after the meal. No typical patterns were observed in plasma concentrations of glucose and alpha-amino nitrogen. Plasma urea concentration rose 2h after feeding and dropped during the following 6 to 8 h. There were no effects of dietary carbohydrate composition on growth hormone concentration but plasma insulin was significantly reduced with the diet high in sugar-beet pulp. Furthermore, the insulin profile showed peaks after each meal with the barley diet but only after the afternoon feeding with the diet high in sugar-beet pulp.

Signifiance of production performance traits as indicators of animal welfare

The first aim of domestication of farm animals is to control and increase the animal performance traits in order to satisfy economically the requirements of man for food with great biological value. The profit of animal production depends on economical factors and performance traits : the former are not related to animal welfare but the latter are influenced by all the constraints imposed to the animals. The literature as the clinical observations show that animals are very sensitive to modifications in the conditions of management, micro-climate and indoor equipment of the buildings. The purpose of improvement of farm conditions is to tend to the best economical arrangement between animal welfare and stockman welfare.

Discriminating power of the nylon bag technique and the pepsin-cellulase method to detect less commonly used components included in concentrates for dairy cows

Abstract The nylon bag technique and the pepsin-cellulase method were used to detect the presence of fat and protein of low degradability in concentrates for dairy cows. Protected or non-protected fat and formaldehyde-treated soya bean meal or fish meal were used as single or double substitutions in the concentrates. Dry matter disappearance from nylon bags was reduced when the less commonly used components were included separately or in combination. Nitrogen disappearance was also reduced when formaldehyde-treated soya bean meal or fish meal were mixed in the concentrates. There was a tendency for the organic matter digestibility measured by the enzymatic method to be slightly higher in the concentrates with single protein substitutions, while a decrease in organic matter digestibility was observed in the single fat substitutions and the double substitutions. A strong and significant correlation was found between the net energy content calculated from the organic matter digestibility values obtained by the enzymatic method and published values.

Effect of Grazing Method, Nitrogen Level, Supplementary Feeding and Stocking Rate on the Performance of Young Grazing Bulls

In 1981 and 1982 an experiment on beef production on pasture with growing fattening young bulls was started on permanent pastures situated on the plateau of the Belgian Ardennes. Rotational grazing and set-stocking were compared in association with the following factors: stocking rate, energetic concentrate supplement level and N-fertilizer intensity.

Effect of sodium hydroxide treatment on chemical composition and in vitro and in vivo digestibility of hay

The effect of NaOH spray treatment on hay digestibility was studied by in vitro and in vivo methods. Four hay types were compared: untreated long or shredded hay and shredded hay treated with 3% and 6% NaOH. In vitro digestibility was measured by three methods: the Tilley and Terry procedure, a one-stage nylon bag technique (rumen digestibility only), and a two-stage nylon bag technique (rumen digestion + pepsin - HCl digestion). In vivo digestibility was estimated on eight young bulls given the four hay types at two levels according to a 2 x 2 latin square. In vitro and in vivodigestibilities of dry matter, organic matter and crude fiber were increased by the NaOH treatment. Both in vitro and in vivo techniques revealed the existence of an optimum NaOH concentration which in our experiments was close to the 3% treatment.