Growth of Holstein calves from birth to 90 days: the influence of dietary zinc and BLAD status.

The main objective of this study was to describe Holstein neonatal growth and development as influenced by dietary zinc supplementation and the CD18 genotype, both of which may affect immune competence. Holstein calves (n = 421), after being fed colostrum, were brought to a calf facility, randomly assigned to one of four zinc supplementation groups (control at 40 mg Zn/kg DM or the control diet supplemented with an additional 60 mg Zn/kg DM provided as either zinc sulfate, zinc lysine, or zinc methionine), weighed, and measured for morphometric growth parameters. Measurements were repeated at 30, 60, and 90 d. Calves were also genotyped for the presence of the mutant D128G CD18 allele, which, if present in two copies, causes bovine leukocyte adhesion deficiency. Zinc supplementation above 40 mg Zn/kg DM, regardless of the chemical form, did not accelerate growth (P > 0.25). Further, overall calf growth performance was not suppressed or improved (P > 0.4) in calves heterozygous at the CD18 locus relative to calves homozygous for the normal CD18 allele, although genotype negatively affected some morphometric measurements (P < 0.05). Using these data, quadratic models of early growth were generated as a preliminary step to develop growth criteria that will allow producers, veterinarians, and animal scientists to identify poor growth performance early in neonatal life. Such criteria provide the basis for tools to improve economic performance.

Serum zinc and copper concentrations in relation to spontaneous abortion in cows: implications for human fetal loss.

The purpose of this study was to investigate the effect of the status of dietary zinc and serum zinc and copper concentrations on the risk of fetal loss in 570 cows. three herds received no supplements (herds 1, 3, 4), while cows in herd 2 received supplements of either 7 g zinc week-1 (n = 118), as zinc methionine, or a control diet containing methionine (n = 128). Serum zinc, copper and metallothionein concentrations were determined once a month throughout gestation. Logistic regression and survival analysis were used to examine for associations between risk of fetal loss and serum zinc, copper, copper:zinc, or metallothionein concentrations, supplement level, and maternal age at conception. The risk of fetal loss increased when both serum zinc decreased and copper concentrations increased (P < 0.0001; relative risk = 10.28, 95% confidence intervals = 4.69, 22.5). The attributable risk, for a decline in the zinc concentration by 10 mumol l-1 and an increase in the copper concentration by 5 mumol l-1 was 90.27%. Methionine-supplemented cows had a higher risk of fetal loss compared with zinc-methionine-supplemented cows (one-tailed P = 0.0375; relative risk = 2.98). Cows in herds 1, 3 and 4 had a higher risk for abortion than did zinc-methionine-supplemented cows in herd 2 (relative risk = 26.27, 95% confidence intervals = 2.31, 299.38; relative risk = 40.87, 95% confidence intervals = 3.50, 458.43; relative risk = 41.53, 95% confidence intervals = 3.77, 457.02, respectively). Our results suggest that inflammation and zinc nutriture may play an important role in fetal loss in dairy cows.

Trace element deficiencies in cattle.

Deficiency of cobalt, copper, iron, iodine, manganese, selenium, or zinc can cause a reduction in production. Reduced production occurs most commonly when a deficiency corresponds to the phases of growth, reproduction, or lactation. Because of environmental, nutrient, disease, genetic, and drug interactions, deficiencies of single or multiple elements can occur even when the levels recommended by the National Research Council for these nutrients are being fed. Additionally, random supplementation of trace elements above National Research Council recommendations is not justified because of the negative interaction among nutrients and potential toxicosis. Evaluation of trace element status can be difficult because many disease states will alter blood analytes used to evaluate nutrient adequacy. Proper dietary and animal evaluation, as well as response to supplementation, are necessary before diagnosing a trace element deficiency.

Vitamin deficiencies in cattle.

Deficiencies of vitamins A, D, K, E and thiamin can cause severe limitations in beef production. In particular, vitamin A and E can be common causes of lost profit, secondary to limitations of reproductive and growth potential. Prolonged dry periods will reduce available A and E in pasture forage, as can ensiling and prolonged storage of harvested feedstuffs. Polioencephalomalacia is a thiamin responsive disorder, associated with high concentrate feeding and lush pastures. Antimetabolites, such as amprolium, will cause thiamine deficiency when fed in excess. Recent information has shown improved performance with supplemental beta carotene and niacin. The positive responses in reproductive performance, noted with cattle fed supplemental beta carotene, was independent of vitamin A. Supplementation of vitamins above National Research Council recommendations can be justified. However, proper evaluation of feed and animal status, and documentation of a response to supplementation is necessary before diagnosing deficiencies of specific nutrients.

An epidemiologic study of mortality in veal calves subsequent to an episode of zinc toxicosis on a California veal calf operation using zinc sulfate-supplemented milk replacer.

Ninety-five 3- to 6-month old male Holstein veal calves were evaluated after an episode of zinc toxicosis, to describe clinical signs and to identify management and/or host-related factors that may have contributed to death. Clinical signs appeared 23 days after feeding of milk replacer commenced. Of 85 calves examined, 64 had pneumonia (75.5%), 62 had ocular signs (72.9%), 46 had diarrhea (54.1%), 34 were anorectic (40.0%), 15 were bloated (17.6%), 8 had cardiac arrhythmias (9.4%), 3 had convulsions (3.5%), and 3 were polydipsic/polyphagic (3.5%). Clinical signs began to appear when calves each were being fed approximately 1.5 to 2.0 g of zinc/day and exposed to a cumulative zinc intake of 42 to 70 g, from a milk replacer containing 706 micrograms of elemental zinc/g of milk replacer. Of 95 calves studied, 1 died before zinc was supplemented, 16 died during the episode, 12 were euthanatized, 1 was lost to follow-up evaluation, 1 was culled, and 64 were slaughtered. Deaths attributable to zinc toxicosis were observed between 25 and 53 days after the milk replacer was supplemented with zinc. Calves died while being exposed cumulatively to 30 to 66 g of zinc. The factors of previous pneumonia severity, age, cumulative daily exposure to zinc, and calf location within a bay were examined for possible associations with mortality, using stepwise logistic regression. Though younger calves tended to have a higher mortality than older calves, neither age category nor severity of pneumonia, before zinc supplementation, accounted for a significant mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Economic losses from an episode of zinc toxicosis on a California veal calf operation using a zinc sulfate-supplemented milk replacer.

An episode of zinc toxicosis in 95 veal calves caused $29,602 in losses to the producer ($315/affected calf), most of them direct, out-of-pocket losses. Increased calf mortality and increased veterinary service costs accounted for a majority (70%) of the losses. Reduction of losses may have been accomplished by removing the source and increasing the roughage content in the diet, or by shipping the animals for immediate slaughter. Given the magnitude of the financial loss, especially those associated with calf mortality, it was concluded that producers should refrain from using large amounts of mineral supplements unless a deficiency has been diagnosed.