“When we take care of immunity, performance follows,” said Zinpro nutritionist Connie Larson, PhD, in a presentation to the Academy of Veterinary Consultants last week. And balanced nutrition, she says, is a key factor in building immunity and optimizing production in cattle, with proper levels of protein, energy, minerals, vitamins and water all critical.
Minerals particularly are involved in cattle reproduction, rumen function, fetal development, milk production and development of the immune system. She says pharmaceutical companies have developed effective vaccines and vaccination programs, but nutrition can be a limiting factor in how well those programs work.
Early in the production cycle, minerals and micro-nutrients in the gestating cow’s diet influence development of the fetus’ organs and tissues and its long-term immunity. An appropriate mineral program in gestating cows also benefits colostrum quality, affecting pre- and post-weaning performance of calves. A calf’s trace-mineral status at weaning also plays a critical role in its immune response as it moves through later production stages.
Dietary zinc, copper, manganese and cobalt influence development of the animal’s immune system, Larson says, and sometimes are at low levels in soils and forages. Antagonistic elements, such as sulfur or iron in feed or water, can also contribute to mineral deficiencies in cattle.
Sulfur intake, for example, can inhibit the animal’s utilization of copper with detrimental effects on health and performance. Sulfur intake can come from several sources including feed and water, adding up to reach excessive levels. Particularly during times of drought, the sulfur concentration in pond water can build up, along with concentrations of other minerals, reducing palatability of the water and leading to excess sulfur intake. Distillers’ grains also tend to be high in sulfur, potentially leading to excessive intake or even toxicity if sulfur levels also are high in water and forage.
Larson says calves often have marginal mineral deficiencies, which do not manifest as direct symptoms but result in compromised immune systems and reduced performance. This year, she says, calves coming off drought-stricken pastures where quality and quantity of forage have been limited, the chance of mineral deficiencies increases even in areas where mineral levels in forage are usually adequate.
Several research trials have shown that incorporating mineral supplements in a preconditioning program results in improved gains in the feedyard, Larson says. Providing a supplement through a 28- to 45-day weaning period can make up for deficiencies as calves come off depleted pastures, and optimize levels of critical minerals in tissues. Larson adds that producers have flexibility to design programs that fit their management system, as supplementing minerals prior to weaning, after weaning or both can benefit calves through the transition.