An attempt was made to improve the protein quality supplied in milk replacers containing soy protein by supplementing Thr, Met, and Lys to the milk replacers fed to calves. Six Holstein x indigenous male calves were fitted with single cannulas at the end of the ileum. Calves were fed milk replacers containing skim milk (86%) and whey (14%) proteins or skim (43%), whey (14%), and soy (43%) proteins either with or without amino acid (AA) supplementation according to a double 3 x 3 Latin square design. Average daily gain, N retention, and ileal digestibilities of dry matter, N, and AA were significantly higher for calves fed the milk replacer containing skim milk protein than for calves fed the milk replacer containing soy protein. Average daily gain, N retention, and ileal digestibilities of dry matter, N, and AA were significantly higher for calves fed the milk replacer containing soy protein plus AA supplementation than for calves fed the milk replacer containing the soy protein without AA supplementation. Therefore, supplementation of a milk replacer containing the soy protein without AA supplementation. Therefore, supplementation of a milk replacer containing soy protein with limiting AA that correspond to the AA found in milk protein can considerably improve the protein quality of that milk replacer for the preruminant calf.

In addition to reduced nutrient intake, an environmental thermal load may directly affect milk yield in heat-stressed dairy cows. Feeding and lying behaviors of early lactation cows fed low fiber diets containing neutral detergent fiber (NDF) from roughage and nonforage fiber sources (NFFS) were investigated under summer conditions in Thailand. Immediately after calving, 30 multiparous cows (87.5% Holstein × 12.5% Sahiwal) were randomly allocated to dietary treatments for 63 d in a completely randomized design. The dietary treatments contained 25% of dry matter (DM) as dietary NDF. The control diet consisted of 13.9% roughage NDF from rice straw (RS). Two additional treatments were created by replacing 3.9% of DM with NDF from either soy hulls (SH) or cassava (Manihot esculenta Grantz) residues (CR), so that the roughage NDF content was reduced to 10%. During the experimental period, the minimum and maximum temperature-humidity indices (THI) were 86.4±2.5 and 91.5±2.7 during the day and 74.2±2.1 and 81.0±2.5 during the night, respectively, indicating conditions appropriate for induction of extreme heat stress. The duration of feeding and lying bouts decreased linearly with increasing THI. The DM intake during the day was greater for cows fed diets containing SH and CR than for those fed the diet containing NDF from RS. The number of meals during the day and night was lower, whereas meal size and meal length during the day and night were greater for cows fed diets containing SH and CR. Cows fed diets containing SH and CR lay down less frequently and longer during the day. These results suggest that under the severe heat stress during the day, early lactation cows fed the diet containing NFFS increased DM intake by increasing meal length and meal size rather than by increasing meal frequency and they spent more time lying. Cows fed diets containing NDF from SH and CR produced more 4% fat-corrected milk, lost less body weight, and had lower rectal temperatures measured at the 1530h milking. Therefore, reducing the filling effect may contribute to reducing heat load derived from the change in feeding and lying behavior. This should be considered as a factor for impairing productivity of heat-stressed early lactation cows.

This experiment was conducted to determine the effects of pineapple stem by-product silage as a feed source in total replacement of Napier or corn silages on growth performance, feed intake and feed efficiency, ruminal fermentation, carcass characteristics and meat quality of Holstein crossbred steers. Forty-eight steers with an average age of 18 months (448.6 ± 51.5 kg) were randomly allocated to three groups (one diet per group) in a completely randomized design. Steers were fed total mixed ration (TMR) containing a roughage-to-concentrate ratio of 20 : 80. The TMR diets contained Napier grass silage (nTMR), whole corn silage (cTMR) or pineapple stem silage (pTMR) and were offered ad libitum for six months. The results revealed that pTMR and cTMR diets resulted in a significantly higher weight gain than nTMR. These results were observed because pTMR and cTMR diets provided more N-free extract (NFE) total digestible nutrients (TDN) than nTMR diet, and the feed conversion efficiencies for pTMR and cTMR diets were higher than those of nTMR. Ruminal pH, ammonia-nitrogen and volatile fatty acid concentrations were not significantly different among dietary treatments. The carcass characteristics of steers fed cTMR and pTMR diets included significantly larger rib eye areas than steers fed nTMR, whereas meat quality was not affected by treatment. Additionally, the current research showed that pTMR diet provided the lowest feed cost per gain. The results suggest that pineapple stem by-product could be regarded as a potential feed source for reducing costs in cattle feedlots.

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This study aimed to assess the effects of neutral detergent fiber (NDF) from rice straw on blood metabolites and productivity of dairy cows in the tropics. Eight Holstein×indigenous (75-87.5% Holstein) were randomly allocated to dietary treatments according to a double 4×4 Latin square design. Contents of roughage NDF from rice straw were 12.8, 14.8, 16.8 and 18.8% dry matter (DM) and concentrate NDF content was 10.2% DM, so that levels of dietary NDF were 23, 25, 27 and 29% DM. Dietary treatments were isonitrogenous and isocaloric diets. The average maximum and minimum temperature humidity index during the experimental period were 85.6 and 76.9, respectively. Plasma glucose (p<0.05), dry matter intake and 4% fat corrected milk (p<0.01) decreased with increasing contents of roughage NDF from rice straw, while rectal temperature, serum urea, cortisol, low density lipoprotein-cholesterol (p<0.05), serum total protein and β-hydroxybutyrate (p<0.01) increased. Serum triglyceride, total cholesterol and high density lipoprotein-cholesterol were not affected (p>0.05). Decreased rectal temperature and concentrations of serum cortisol were associated with decreasing levels of β-hydroxybutyrate and serum urea, but with increased concentrations of plasma glucose, DMI and 4% fat corrected milk indicating that lactating cows fed lower fiber diets were in lower oxidative stress. Therefore higher intake and metabolic efficiency in dairy cows fed diets lower in roughage NDF from rice straw would be of an advantage in productive systems under tropical conditions.

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