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This study examined the effects of gradually replacing grass silage with whole-crop barley silage on feed intake, ruminal and total tract digestibility, and milk yield in lactating dairy cows. Four dairy cows in early lactation, equipped with rumen cannulas, were fed 4 diets over four 21-d periods. The diets consisted of 4 forage mixtures of grass silage and whole-crop barley silage supplemented with 8.9 kg/d of concentrates [dry matter (DM) basis]. The proportion of barley silage in the forage was adjusted to 0, 0.20, 0.40, and 0.60 kg/ kg of DM. Ruminal nutrient metabolism was measured on the basis of digesta flow entering the omasal canal. Ammonia concentrations and volatile fatty acid profiles were determined in the rumen fluid. Ruminal digestion and passage kinetics were assessed by the rumen evacuation technique. Replacement of grass silage with barley silage had no effect on DM, digestible organic matter, or neutral detergent fiber (NDF) intake, but starch intake increased, whereas nitrogen and digestible NDF (dNDF) intake decreased. Increases in the proportion of barley silage linearly decreased milk yield, and the molar proportion of acetate in the rumen, and increased that of propionate, butyrate, and valerate. Decreases in milk yield due to inclusion of barley silage were attributed to decreases in diet digestibility and nutrient supply to the animal. Barley silage linearly decreased organic matter digestibility in the total tract and NDF and dNDF digestibility in the rumen and the total tract, and decreased nonammonia N flow entering the omasal canal. No significant differences between diets were noted in the digestion rate of dNDF or passage rate of indigestible NDF from the rumen. Decreases in organic matter and NDF digestibility were attributed to the higher indigestible NDF concentration of barley silage compared with that of grass silage and to the smaller pool size of dNDF in the rumen.

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The objective of this meta-analysis was to develop empirical equations predicting growth responses of growing cattle to protein intake. Overall, the data set comprised 199 diets in 80 studies. The diets were mainly based on grass silage or grass silage partly or completely replaced by whole-crop silages or straw. The concentrate feeds consisted of cereal grains, fibrous by-products and protein supplements. The analyses were conducted both comprehensively for all studies and also separately for studies in which soybean meal (SBM; n = 71 diets/28 studies), fish meal (FM; 27/12) and rapeseed meal (RSM; 74/35) were used as a protein supplement. Increasing dietary CP concentration increased ( P < 0.01) BW gain (BWG), but the responses were quantitatively small (1.4 g per 1 g/kg dry matter (DM) increase in dietary CP concentration). The BWG responses were not different for bulls v. steers and heifers (1.4 v. 1.3 g per 1 g/kg DM increase in dietary CP concentration) and for dairy v. beef breeds (1.2 v. 1.7 g per 1 g/kg, respectively). The effect of increased CP concentration declined ( P < 0.01) with increasing mean BW of the animals and with improved BWG of the control animals (the lowest CP diet in each study). The BWG responses to protein supplementation were not related to the CP concentration in the control diet. The BWG responses increased ( P < 0.05) with increased ammonia N concentration in silage N and declined marginally ( P > 0.10) with increasing proportion of concentrate in the diet. All protein supplements had a significant effect on BWG, but the effects were greater for RSM ( P < 0.01) and FM ( P < 0.05) than for SBM. Increasing dietary CP concentration improved ( P < 0.01) feed efficiency when expressed as BWG/kg DM intake, but decreased markedly when expressed as BWG/kg CP intake. Assuming CP concentration of 170 g/kg BW marginal efficiency of the utilisation of incremental CP intake was only 0.05. Increasing dietary CP concentration had no effects on carcass weight, dressing proportion or conformation score, but it increased ( P < 0.01) fat score. Owing to limited production responses, higher prices of protein supplements compared with cereal grains and possible increases the N and P emissions, there is generally no benefit from using protein supplementation for growing cattle fed grass silage-based diets, provided that the supply of rumen-degradable protein is not limiting digestion in the rumen.

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.

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n = 58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2 L of milk replacer 3 times per day. The milk replacer contained 116 g of DM/L, resulting in an average DM intake of 4.8 g of DM/kg of body weight0.75 (BW0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.

The present experiment was conducted to study diet digestibility, feed intake, animal performance and carcass characteristics of growing dairy bulls offered diets based on whole-crop barley, a mixture of whole-crop barley and hairy vetch (Vicia villosa Roth.) or a mixture of whole-crop wheat and hairy vetch relative to moderate digestible grass silage-based diet. The feeding experiment with 24 Finnish Ayrshire and 8 HolsteinFriesian bulls included 4 forage feeding treatments: grass silage (G), whole-crop barley and hairy vetch mixture silage (BHV), whole-crop wheat and hairy vetch mixture silage (WHV) and whole-crop barley silage (B). In all treatments animals were offered silage ad libitum. The amount of concentrate supplementation was 36 g (W 0.75 ) -1 per animal per day for all treatments. The concentrate ration included rolled barley and rapeseed meal. Differences between the treatments were compared using an a priori test (Dunnett's test) so that comparison of the diets was based on the G diet. The animals were fed the experimental diets from day 240 to finish at day 505 of age. During the experiment the average concentrate proportions of G, BHV, WHV and B diets were 437, 424, 426 and 423 g dry matter (DM) (kg DM) -1 , respectively. There were no significant differences in silage DM intake or in the total DM intake (DMI) (kg DM d -1 ) between treatments. However, DMI kg -1 W 0.75 tended to be 3.5% higher (p = 0.09) in the B diet than in the G diet. Due to increasing energy intake, the gain of the bulls was higher with the G diet than with the WHV diet (p < 0.05). BHV and B diets did not differ from the G diet in gain. Treatments had no significant effect on the dressing proportion or carcass conformation. The carcass fat score of WHV bulls was 29% lower (p < 0.05) than that of the G bulls, but BHV and B diets did not differ from the G diet in carcass fatness. The feed conversion rate (DM intake kg -1 carcass gain) of the bulls was better (p < 0.001) and protein conversion (g AAT kg -1 carcass gain) tended to be better (p = 0.07) with the G diet than with the WHV diet. BHV and B diets did not differ from the G diet in any feed conversion parameters. It can be concluded that replacing moderate digestible grass silage with whole-crop wheat and hairy vetch mixture silage decreased the carcass gain of growing dairy bulls due to lower energy intake and poorer feed conversion. Instead, replacing moderate digestible grass silage with whole-crop barley or with whole-crop barley and hairy vetch mixture silage resulted in no differences in the performance or carcass characteristics parameters of growing dairy bulls.

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