Need for protein supplementation in the diet of growing dairy bulls fed total mixed ration based on moderate digestible grass silage and barley

Abstract

The objective of the present experiment was to study the need for the protein supplementation in the diet of growing dairy bulls (initial live weight 272 ± 28.5 kg and final live weight 666 ± 31.2 kg, on average) fed total mixed ration based on moderate digestible grass silage and barley. The experiment comprised 24 Finnish Ayrshire bulls and 8 Holstein-Friesian bulls and included four treatments. The control diet (C) consisted of moderate digestible (653 g digestible organic matter in dry matter (DM) grass silage (450 g kg -1 DM), barley grain (275) and barley fibre (275) without protein supplementation. Three isonitrogenous experimental diets included also extra protein, i.e. (1) rapeseed meal (RSM) (supplementation 530 g DM per animal day -1 ), (2) wet distillers' solubles (WDS) (600 g) and (3) a mixture of barley protein (90% of fresh weight) and wet distillers' solubles (10) (BPWDS) (480 g). In all isonitrogenous diets the crude protein content of concentrate increased from 137 to 150 g kg -1 DM (9%) compared with the C diet. All bulls were fed total mixed ration ad libitum. The energy content of all diets was 11.6 MJ kg -1 DM. The live weight gain of the bulls tended to be higher with the BPWDS diet than with the C diet (C 1214 vs. BPWDS 1301 g d -1 ; p = 0.10), but the treatments had no significant effect on carcass gain, feed conversion or slaughter parameters. Only the BPWDS diet differed significantly from the C diet in DM (C 9.69 vs. BPWDS 10.38 kg DM d -1; p < 0.01) and energy intake ; p < 0.05). The apparent organic matter digestibility (OMD) was 5% higher in the BPWDS diet than in the C diet (p < 0.001), but the RSM and WDS diets did not differ from the C diet in OMD. The results indicate that the supply of protein in dairy bulls is most probably adequate with moderate digestible, well-preserved grass silage and barley-based concentrates when intake of digestible organic matter is high enough to support microbial protein synthesis in the rumen.

Effects of grass-red clover silage digestibility and concentrate protein concentration on performance, carcass value, eating quality and economy of finishing Hereford bulls reared in cold conditions

“…The carcass traits were unaffected by the concentrate protein concentration being consistent with recent studies (Huuskonen et al 2007, Huuskonen et al 2008, Huuskonen 2009a). On the contrary, increased protein intake tended to increase the carcass fatness of steers and heifers Robson 1995, Steen 1996a).…”

“…The digestibility of dietary OM was unaffected by concentrate protein concentration, in accordance with Huuskonen et al (2007Huuskonen et al ( , 2008 and Huuskonen (2009a). In numerous studies (e.g.…”

“…In the present study, there was no benefit from the higher concentrate protein concentration, suggesting that the amino acid supply from feed protein and microbial protein synthesis in the rumen was sufficient on diet L for a high daily LWG. Correspondingly, in recent studies (Huuskonen et al 2007, Huuskonen et al 2008, Huuskonen 2009a) with heavy dairy-breed bulls, rapeseed meal supplementation did not improve the growth rate, as also observed with heavy steers (Steen 1988b, Steen 1996a) and suckled beef bulls (Drennan et al 1994) fed fish meal/soybean meal supplementation.…”

“…In several studies, protein supplementation has not increased the growth rate (e.g. Steen 1996a, Huuskonen et al 2008, Huuskonen 2009a), but there is evidence that finishing cattle may respond to supplementary protein in barleybased concentrates when the grass silage digestibility is moderate or low (Waterhouse et al 1985) and in situations where the animals have very high growth potential (Steen 1996b). In some studies, excess protein supplementation has increased carcass fat classification (Steen and Moore 1988, 1989, Steen 1996a) but Berge et al (1993) reported that steers which were given protein supplementation had leaner carcasses than steers not given protein supplementation.…”

Performance of growing dairy bulls offered diets based on silages made of whole-crop barley, whole-crop wheat, hairy vetch and grass

“…The live weight gain (LWG) was calculated as the difference between the means of initial and final weights. The estimated rate of carcass gain was calculated by assuming an initial carcass weight of 0.50 of initial LW which was used also in previous studies by Huuskonen et al (2007bHuuskonen et al ( , 2008Huuskonen et al ( , 2009. After slaughter in a commercial meat plant carcasses were weighed hot.…”