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ABSTRACT: Adding milk replacer powder (MRP) to whole milk during the entire preweaning period can increase growth but raises concern because of low starter feed intake and slumps in ADG at weaning and postweaning. In the current study, effects of adding MRP to pasteurized whole milk (PWM) during d 10 to 41 or d 10 to 59 of age were investigated in comparison with PWM. Calves (24 females and 21 males; 39.8 ± 1.85 kg BW) were randomly allocated to 1 of 3 treatments: (1) conventional protocol, 5 L/d PWM from d 3 to 56, and 2.5 L/d from d 57 to 59 of age (CONV; TS intake = 31.9 kg), (2) short duration of adding MRP to PWM protocol, 5 L/d PWM from d 3 to 9, 5 L/d PWM + MRP (18% TS) from d 10 to 41, 5 L/d PWM from d 42 to 56, and 2.5 L/d PWM from d 57 to 59 (SHD; TS intake = 42.3 kg), (3) long duration of adding MRP to PWM protocol, 5 L/d PWM from d 3–9, 5 L/d PWM + MRP from d 10–56, 2.5 L/d PWM + MRP from d 57–59 (LD; TS intake = 47.7 kg). The osmolality of PWM and PWM + MRP was 278 and 519 mOsm/L, respectively. Calves were weaned on d 60, and the study terminated on d 75. There was a treatment × time interaction for starter intake, where intake was greater for CONV than other treatments from d 14–41 and was greater in CONV than LD during d 42 to 48 and d 56 to 62 of age. Final BW was lower in CONV calves than LD calves. Weaning BW and overall hip height were lower in CONV calves than other treatments. The CONV calves had lower ADG at d 14 to 27 and d 35 to 41, and SHD calves had lower ADG at d 42 to 48 than other treatments. Calves fed CONV treatment had lower ruminal acetate and greater propionate than SHD calves during preweaning. Calves fed LD treatment had lower total VFA and tended to have greater ruminal pH than other treatments. Calves fed CONV had greater neutrophils and neutrophils/lymphocytes ratio and lower lymphocytes than other treatments. Glucose concentration was greater for LD versus other treatments at d 56, and lower for SHD versus other treatments at d 70 of study. Insulin concentration and homeostatic model assessment of insulin resistance index were greater in LD compared with other treatments during preweaning but were not different postweaning. Serum BHB was greater in CONV than other treatments. Albumin was greater for CONV versus other treatments at d 56, however, it was greater in LD-fed calves at d 70 of study. Results indicate that feeding a PWM + MRP to the calves during the entire preweaning period resulted in lower starter feed intake around weaning, but overall starter intake was similar with a greater final BW and fewer health-related issues throughout the study. Shifting a PWM + MRP to the conventional whole milk at d 40 of age decreased the ADG of calves.

BackgroundEstimation of the quantity of colostral IgG or serum IgG absorbed following ingestion of colostrum by calves is essential for monitoring the effectiveness of colostrum feeding practices on dairy farms. Milk total solids concentrations determination is a critical part of quality assessment of nonsaleable whole milk prior to feeding to calves. To date, on-farm methods to assess colostral IgG, serum IgG or milk total solids concentrations have been performed separately with various instruments. The objective of this study was to evaluate the diagnostic performance of a single electronic, hand-held refractometer for assessing colostral and serum IgG concentrations and milk total solids in dairy cattle. Colostral IgG, serum IgG and milk total solids concentrations were determined by the refractometer. Corresponding analysis of colostral and serum IgG concentrations were determined by radial immunodiffusion (RID) while milk total solids were determined by spectrophotometry. Sensitivity and specificity of the refractometer for colostrum and serum samples were calculated as determined by RID. Sensitivity and specificity of the refractometer for milk samples was calculated as determined by spectrophotometry.ResultsThe sensitivity of the refractometer was 1 for colostral IgG, serum IgG and milk total solids determinations. Specificity of the refractometer was 0.66, 0.24 and 0 for colostral IgG, serum IgG and milk total solids determinations, respectively. The refractometer underestimated colostral IgG, serum IgG and milk total solids concentrations compared to the concentrations determined by RID or spectrophotometry.ConclusionsThe refractometer was an acceptable, rapid, convenient on-farm method for determining colostral IgG and milk total solids. The refractometer was not an acceptable method for determination of serum IgG concentrations as it severely underestimated the serum IgG concentrations.

The effect of copper and zinc supplementation on milk composition like milk fat, milk SNF and milk total solid was tested in pre and post partum feeding trial, with 20 lactating Kankrej cows, divided in four groups (control, copper, zinc, and copper-zinc combination). Milk fat percentage was observed highest in supplemented combination group while milk SNF and total solid were highest in zinc supplemented group. The significant effect ((P≤ 0.05)) of micronutrient supplementation on milk fat, milk SNF and total solids was observed in present study. The fat content was significantly (P≤ 0.01) high during the first days of lactation and decrease up to the day 45th. The interaction effect due to the group x days was found non-significant. Thus improvement of the nutritional status improved the milk production as well as milk composition. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate whether lactation stage and animal age influence the milk composition of grazing donkeys. Jennies were maintained in an exclusively free-range system during the summer season and grazed on a mixed pasture of native grass. Milk samples were collected by manual milking twice a day, two days a week. Acidity, density, total solids, solids-non-fat, fat, protein, casein, lactose, somatic cell count (SCC), and the proportion of nitrogen fractions of the milk were determined. Milk production was 0.61 kg/animal/day. Lactose, fat, acidity, SSC, and whey protein were not affected by the lactation stage. However, milk total solids, solids-non-fat, protein, casein, and nitrogen fractions (non-protein nitrogen and true protein) decreased as the lactation stage progressed. Total solids and protein decreased with the lactation stage, whereas aging was associated with increased protein and fat concentration in milk. These results indicate that the impact of jenny's age on milk fat was lower than on protein content; for every year of age, milk fat percentage increased by 0.023 and milk protein increased 0.13% units. Therefore, the lactation stage and jenny's age are the determinants of milk composition in grazing donkeys. • Fat and protein content in donkey milk increases with age. • Milk total solids in donkey milk are lower in the late stages of lactation. • Milk from older jennies in early lactation may produce higher yield of yogurt. • Milk from grazing donkeys has similar composition than concentrated-fed animals. [ABSTRACT FROM AUTHOR]