Yield and composition of milk from Friesian cows grazing either perennial ryegrass or white clover in early lactation

Abstract

SUMMARYThe yield and composition of milk from Friesian cows grazing either perennial ryegrass (Lolium perenne) (G, ten cows) or white clover (Trifolium repens) (C, nine cows) were evaluated between d 21 and 129 post partum. The two forages, of similar digestible energy content, were the sole source of nutrients and were offeredad lib. (exp. 1). Digestion and flow at the duodenum were measured on 13 occasions in early lactation with comparable cows fitted with rumen and duodenal cannulae and grazing similar forages (exp. 2). The gross milk yield (22·2, G; 25·0, C, kg/dP< 0·05) and the yield of protein (0·66, G; 0·77, C, kg/d,P< 0·01) were higher, but the protein content was similar and the fat content lower for cows fed C compared with G. Cows fed G were heavier at the beginning of the experiment and lost weight more rapidly than cows fed C. Milk energy output, adjusted for tissue energy gain or loss, was 83·9 for cows fed C compared with 71·8 MJ/d for cows fed G (P< 0·001), during the period of tissue energy repletion (weeks 11–18). From week 18 to the end of lactation all cows from exp. 1 were fed silagead lib. and 502 kg dry matter of concentrates. The total (305 d) difference in lactation response to grazing C compared with G was 931 1 (5657 1, C; 4726 1, G); this was a direct response during the experiment of 301 1 and a residual response of 630 1. In exp. 2, more organic matter (6·47, G; 8·01, C, kg/ d,P< 0·001), and more non-ammonia N (433, G; 575, C, g/d,P< 0·001) entered the duodenum of cows grazing C compared with G.

Doğal Meralanrdan Toplanan Ak Üçgül (Trifolium repens L.) Genotiplerinin Performanslarının Belirlenmesi

“…Accessions growing in different climatic conditions could show different morphological and physiological characters. Similar to these genotypes in this study showed different genotypic variance inferring that the bigger genotypic variance the better breeding success (Açıkgöz 2001;Baker and Willıams 1987;Taylor 1985;Thomson 1985;Brock 1983;Brougham 1960). Minimum, maximums and mean values of plant characters are given in Table 1.…”

“…The erect genotypes are suitable to hay yield, but the other group prostrate genotypes are appropriate to be grazed (Açıkgöz 2001) Maintained that erect genotypes give more hay yield than prostrate ones. Prostrate genotypes are more resistant to for animal grazing and they could safely place in establishment meadow (Açıkgöz 2001;Baker and Willıams 1987;Taylor 1985;Thomson 1985;Brock 1983;Brougham 1960).…”

Effects of manipulating the protein content of white clover on silage quality

“…However, this trend was not observed in plants grown in 2000, where the WSC content was more typical of that observed in field grown white clover. Thomson et al (1985) reported a mean WSC content of 102 g/kg DM in field-grown white clover over a 14-week period. The low herbage WSC contents, and the relationship with nitrate application level, suggest that the rate of carbon fixation was limiting at the time of harvest in experiment 1.…”

“…Thomson et al (1985) reported a mean N content of 44 g/kg DM in white clover over a growing season. In contrast to temperate grasses, it is difficult to manipulate the N content of legumes such as white clover, as N 2 fixation makes it difficult to restrict N supply.…”

Effect of forage conservation (hay or silage) on chemical composition of milk

“…Unfortunately, in these two trials, the type of flora (ryegrass or cooksfoot) that can have an effect on milk yield and composition (Demarquilly, 1963;Thompson et (Rowland, 1938), urea, phosphorus and calcium concentrations.…”