The aim of this study was to determine the effects of coated calcium butyrate (CCB) on calf performance and some blood parameters. Sixteen female Holstein calves with a mean age of 3 ± 1 d were divided into two equal groups and fed a milk replacer supplemented with 3 g of coated calcium butyrate (CCB)/day or with no coated calcium butyrate (NCB). The calves had free access to solid feed and water. Body weight was measured at days 3, 12, 24, 36 and 48 (weaning day). Respiratory rate and rectal temperature (within first 4 weeks of life), feed intake and faecal score (during the whole experimental period) were recorded daily. Rumen fluid was taken for volatile fatty acid (VFA) determination on days 33 and 48, and structural growth (rump height, withers height and hip width) was recorded on days 3, 24 and 48. Blood samples were collected on days 1, 12, 24, 36 and 48. Feed intake, average daily gain, feed conversion ratio and structural growth of calves were improved by CCB supplementation. There were no significant differences on rectal temperature, respiratory rate and faecal score between the treatments. Rumen concentration of total VFAs increased and the VFA profile was affected on days 33 and 48 by CCB supplementation. The supplementation of milk replacer of calves with coated calcium butyrate significantly increased serum concentrations of glucose, insulin and β-hydroxybutyrate. Serum concentration of cortisol in the CCB calves was numerically lower than in NCB. In conclusion, supplementation of calves' milk replacer with the coated calcium butyrate could improve calf performance. ________________________________________________________________________________

In this experiment the response to niacin supplementation was evaluated. Twelve multiparous Holstein cows were used in a replicated 4 × 4 Latin square statistical model in four 24 d periods as replicates. At the onset all the cows were in early lactation with days in milk (DIM) at 60.1 ± 16.1 and an average milk yield of 31.4 ± 5.44 L/d. The treatments were: N0 -control (no niacin supplement); N1 -control + 12 g niacin/d; N2 -control + 14 g niacin/d and N3 -control + 16 g niacin/d. Means were compared with the Duncan ' s least range test. Milk yield, fat-corrected milk (FCM, 3.5%) and total solids percentage (TS) were significantly higher in the N2 compared to the other treatments. There were no significant differences between treatments in milk fat and milk lactose percentages, but milk fat yield was significantly higher and milk fat percentage numerically higher in the N2 than in the other treatments. Milk protein yield and percentage were highest in N2, but milk protein percentage was not significantly different between the N2 and N1 treatments. Milk solids non-fat (SNF) percentage was the highest for N2. Evaluation of blood plasma parameters showed that 14 g niacin (N2) supplementation resulted in a significantly higher glucose concentration and the lowest ß-hydroxybutyrate (BHBA) and nonesterified fatty acids (NEFA) concentrations as compared to the other treatments. This study suggested that the optimal level of niacin supplementation was 14 g niacin/cow/d. .

The objective was to study the effects of partial replacement of soybean meal (SBM) with xylose-treated SBM (XSBM) as a source of rumen undegradable protein (RUP) in the starter concentrate of calves on performance, health status and selected blood metabolites. Twenty-one female Holstein dairy calves (body weight=39.6±2.3 kg) were randomly assigned to 3 groups (n=7 each): i) starter concentrate with 25% SBM [control (CTR)]; ii) starter concentrate with 17.5% SBM +7.5% XSBM (7.5XSBM); and iii) starter concentrate with 12.5% SBM+12.5% XSBM (12.5XSBM). Calves received 2 L of milk twice daily, with ad libitum access to starter concentrates from d 4 until weaning (d 56). Performance and health status were recorded throughout the experiment. Blood samples collected on d 4, 35 and 56 were assayed for concentrations of glucose, total protein (TP), and plasma urea nitrogen (PUN). Starter intake (560, 400, and 420 g/d for CTR, 7.5XSBM, and 12.5XSBM, respectively), average daily gain (0.67, 0.6 and 0.57 kg/d), and feed to gain ratio (0.83, 0.67, and 0.74) were affected by treatments (P<0.05). Hearth girth, height at withers, body length, rectal temperature, faecal score, and respiratory score did not differ among treatments. Mean plasma glucose and TP were not affected by treatments, whereas PUN in the 12.5XSBM group was lower than in the other groups (P<0.05). In conclusion, the present results showed that partial replacement of SBM by XSBM may improve efficiency of dietary protein utilisation in pre-weaned calves, which warrants further studies.[page 139] growth performance, health status, and selected blood metabolites including glucose, total protein (TP) and plasma urea nitrogen (PUN) in Holstein dairy calves.

The current study aimed to investigate if different sources of supplemental zinc (Zn), manganese (Mn), copper (Cu), and selenium (Se) fed to dry and lactating dairy cows affect reproductive performance, lameness status, and colostrum production. The experiment was carried out on 60 multiparous non-lactating Holstein cows in a commercial dairy herd. The cows received randomly mineral mixtures in three treatment groups containing inorganic, 25% organic-75% inorganic, or 50% organic-50% inorganic forms of Zn, Mn, Cu, and Se starting from approximately 3 weeks prior to calving up to 90 days postpartum. Supplements were included in rations and fed twice a day. Reproductive parameters including days to first service, days to first estrus, service per conception, and conception rate were investigated. After parturition, colostrum production, composition, and immunoglobulin G(1) concentration were determined. Lameness, as an indicator of trace minerals deficiency, was evaluated in a five-score scale. The source of mineral supplement only numerically improved the assessed parameters excluding colostrum fat, protein, and ash percent. The organic form of supplements did not significantly affect reproductive performance, lameness score, or colostrum production.

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