The need for vitamin D supplementation of dairy cattle has been known for the better part of the last century and is well appreciated by dairy producers and nutritionists. Whether current recommendations and practices for supplemental vitamin D are meeting the needs of dairy cattle, however, is not well known. The vitamin D status of animals is reliably indicated by the concentration of the 25-hydroxyvitamin D [25(OH)D] metabolite in serum or plasma, with a concentration of 30ng/mL proposed as a lower threshold for sufficiency. The objective of this study was to determine the typical serum 25(OH)D concentrations of dairy cattle across various dairy operations. The serum 25(OH)D concentration of 702 samples collected from cows across various stages of lactation, housing systems, and locations in the United States was 68±22ng/mL (mean ± standard deviation), with the majority of samples between 40 and 100ng/mL. Most of the 12 herds surveyed supplemented cows with 30,000 to 50,000 IU of vitamin D/d, and average serum 25(OH)D of cows at 100 to 300 DIM in each of those herds was near or above 70ng/mL regardless of season or housing. In contrast, average serum 25(OH)D of a herd supplementing with 20,000 IU/d was 42±15ng/mL, with 22% below 30ng/mL. Cows in early lactation (0 to 30d in milk) also had lower serum 25(OH)D than did mid- to late-lactation cows (57±17 vs. 71±20ng/mL, respectively). Serum 25(OH)D of yearling heifers receiving 11,000 to 12,000 IU of vitamin D/d was near that of cows at 76±15ng/mL. Serum 25(OH)D concentrations of calves, on the other hand, was 15±11ng/mL at birth and remained near or below 15ng/mL through 1mo of age if they were fed pasteurized waste milk with little to no summer sun exposure. In contrast, serum 25(OH)D of calves fed milk replacer containing 6,600 and 11,000 IU of vitamin D/kg of dry matter were 59±8 and 98±33ng/mL, respectively, at 1mo of age. Experimental data from calves similarly indicated that serum 25(OH)D achieved at approximately 1mo of age would increase 6 to 7ng/mL for every 1,000 IU of vitamin D/kg of dry matter of milk replacer. In conclusion, vitamin D status of dairy cattle supplemented with vitamin D according to typical practices, about 1.5 to 2.5 times the National Research Council recommendation, is sufficient as defined by serum 25(OH)D concentrations. Newborn calves and calves fed milk without supplemental vitamin D, however, are prone to deficiency.

To observe the effects of supplemental dietary d-α-tocopherol in relation to dietary energy on growth and immune status in dairy calves, 32 newborn Holstein bull calves were assigned to 1 of 4 treatments for 5 wk in a 2 × 2 factorial, randomized complete block, split-plot design. Calves received moderate growth (MG) or low growth (LG) all-milk dietary treatments, formulated to support daily gains of 0.5 or 0.25 kg/d, respectively, per the dietary energy recommendation for milk-fed calves according to the National Research Council's Nutrient Requirements of Dairy Cattle. Calves in both groups were either injected i.m. with Vital E-A+D (injectable solution of vitamins E, A, and D) on d 1 and supplemented with Emcelle Tocopherol (micellized vitamin E) via milk daily (MG-S and LG-S), or were not supplemented (MG-C and LG-C) during the study period. Total weight gain of MG calves was greater than that of LG calves and tended to be greater in MG-S calves than in MG-C calves. Calves receiving vitamin supplementation demonstrated greater concentrations of plasma α-tocopherol, retinol, and 25-(OH)-vitamin D than did control calves, whereas MG calves demonstrated a lower concentration of plasma α-tocopherol than did LG calves. The apparent increased utilization of α-tocopherol by MG calves was accompanied by a rise in serum haptoglobin, a positive acute-phase protein and indicator of inflammation, especially in MG-C calves. Serum amyloid A, also a positive acute-phase protein, was not different among groups, but was elevated from baseline in all groups during wk 1 through 3. Plasma IgG1 concentrations were higher in MG-S and LG-S calves than in their nonsupplemented dietary counterparts, whereas plasma IgG2, IgA, and IgM concentrations were not different among groups. In summary, dietary supplementation of d-α-tocopherol improved plasma α-tocopherol status and tended to increase growth in calves fed for 0.5 kg of average daily gain. Vitamin supplementation ameliorated the rise of serum haptoglobin associated with acute inflammation in MG calves, and may have improved passive transfer of maternal antibody. These results indicate a role for α-tocopherol in prevention of proinflammatory state associated with greater dietary energy and onset of infectious disease.

Four ruminally and duodenally cannulated beef steers (492 +/- 30 kg) were used in a 4 x 4 Latin square design to evaluate the effect of undegradable intake protein (UIP) supplementation on intake, digestion, microbial efficiency, in situ disappearance, and plasma hormones and metabolites in steers fed low-quality grass hay. The steers were offered chopped (10.2 cm in length) grass hay (6.0% CP) ad libitum and 1 of 4 supplements. Supplemental treatments (1,040 g of DM daily), offered daily at 0800, were control (no supplement) or low, medium, or high levels of UIP (the supplements provided 8.3, 203.8, and 422.2 g of UIP/ d, respectively). The supplements were formulated to provide similar amounts of degradable intake protein (22%) and energy (1.77 Mcal of NE(m)/kg). Blood samples were taken at -2, -0.5, 1, 2, 4, 8, 12, and 24 h after supplementation on d 1 (intensive sampling) and at -0.5 h before supplementation on d 2, 3, 4, and 5 (daily sampling) of each collection period. Contrasts comparing control vs. low, medium, and high; low vs. medium and high; and medium vs. high levels of UIP were conducted. Apparent and true ruminal OM and N digestion increased (P < 0.03) in steers fed supplemental protein compared with controls, but there were no differences (P > 0.26) among supplemental protein treatments. There were no differences (P > 0.11) among treatments for NDF or ADF digestion, or total ruminal VFA or microbial protein synthesis. Ruminal pH was not different (P = 0.32) between control and protein-supplemented treatments; however, ruminal pH was greater (P = 0.02) for supplementation with medium and high compared with low UIP. Daily plasma insulin concentrations were increased (P = 0.004) in protein-supplemented steers compared with controls and were reduced (P = 0.003) in steers fed low UIP compared with steers fed greater levels of UIP. Intensive and daily plasma urea N concentrations were increased (P < 0.01) in protein-supplemented steers compared with controls and increased (P < 0.02) for intensive and daily sampling, respectively, in steers supplemented with medium and high UIP compared with low UIP. Supplemental protein increased apparent and true ruminal OM and N digestion, and medium and high levels of UIP increased ruminal pH compared with the low level. An increasing level of UIP increases urea N and baseline plasma insulin concentrations in steers fed low-quality hay.

No abstract

Adipocyte sizes from adipose tissue of mature animals form a bimodal distribution, thus reporting mean cell size is misleading. The objectives of this study were to develop a robust method for testing bimodality of porcine adipocytes, describe the size distribution with an informative metric, and statistically test hypertrophy and appearance of new small adipocytes, possibly resulting from hyperplasia or lipid filling of previously divided fibroblastic cells. Ninety-three percent of adipose samples measured were bimodal (P < 0.0001); therefore, we describe and propose a method of testing hyperplasia or lipid filling of previously divided fibroblastic cells based upon the probability of an adipocyte falling into 2 chosen competing “bins” as adiposity increases. We also conclude that increased adiposity is correlated positively with an adipocyte being found in the minor mode (r = 0.46) and correlated negatively with an adipocyte being found in the major mode (r = −0.22), providing evidence of either hyperplasia or lipid filling of previously divided fibroblastic cells. We additionally conclude that as adiposity increases, the mode of the major distribution of cells occurs at a larger diameter of adipocyte, indicating hypertrophy.