Ration imbalances or deficiencies can result in health concerns.
Nutrition is a critical component of modern swine production. Many of the nutrients that make up swine rations have defined minimums for expected performance. Minimum nutrient levels are necessary to balance rations as cost-effectively as possible.
Although we deal mostly with deficiency concerns, some nutrients can be fed at high enough levels to be detrimental to pigs or the environment.
In addition, interactions between nutrients in swine rations are common and must be carefully considered in formulation.
Case Study No. 1
We were called to a single-site, farrow-to-finish farm to look at a group of 60-80 lb. pigs that were unthrifty. This was a 150-sow farm that batch-farrowed every four weeks. The pigs exhibited a rough hair coat and had skin lesions that were primarily on the underside of the belly. Some pigs had lesions, also on the sides and extended up their backsides.
The lesions were in 10% of the pigs, and appeared to be dry and raised but were not itchy. The appearance of the pigs was similar to “greasy pigs” or mange.
But this skin condition was occurring in a much older pig than was typical for greasy pigs. The lesions were typical of parakeratosis, which is associated with zinc deficiency.
To treat this condition, the farm was using an “all purpose” premix that was designed for pigs, cattle, chickens, etc. The farm changed to a swine premix and the lesions resolved. The pigs responded fairly well with very few long-term consequences.
Although this was a case of feeding a product that did not fit the nutritional needs of the pig, we also see formulation or feedmill omission errors that result in the parakeratosis lesions. Since pigs cannot store zinc in their bodies, visible deficiency symptoms occur in as little as 2-3 weeks.
Case Study No. 2
We were asked to look into an issue on a 1,100-sow farm with a history of concerns from their packer. This was a single-site, farrow-to-finish operation.
During the skinning process at the packing plant, the carcasses from this unit were experiencing too many broken backs that needed to be trimmed. This resulted in trim losses for the farm and additional time spent with each carcass for the packer.
With this history, a lack of bone strength was suspected.
The formulation of the diets appeared correct. However, when we investigated the rations used in late finishing, we found that the limestone (calcium source) and the dicalcium phosphate (phosphorus and calcium sources) were entered incorrectly.
In swine, the level of calcium and phosphorus are important, but the ratio of these nutrients to each other is also important for bone density. In swine finishing diets, we try to run diets with a ratio of 1 part phosphorus to 1.1-1.2 parts calcium.
Because of the formulation entry error, the actual diets fed consisted of 1 part phosphorus to 1.9 parts calcium. Not only was the ratio out of proportion, but the level of available phosphorus in the finishing diet was also below intended targets for late-finishing rations. Correction of the entry error ended the packer concerns.
Case Study No. 3
A 200-sow, multiple-site, farrow-to-finish farm was experiencing Mulberry Heart Syndrome (MHS) in 40-lb. pigs. MHS is considered a vitamin E/selenium responsive disease that manifests itself as sudden death in top-performing pigs.
Examination of the diets for this farm revealed adequate levels of both vitamin E and selenium. Since we are restricted in the United States by the legal maximum level for selenium of 0.3 ppm, we chose to use an organic source of selenium that is better absorbed than the inorganic forms. The vitamin E level was also increased with a more available form.
With some trial and error, the problem appears to have resolved. We believe a high level of iron in the water was limiting the absorption of one or both of these nutrients.
In swine nutrition, issues can arise from diet formulation, nutrient availability, data entry errors and mixing errors. Since nutrition is an evolving science, we gain more knowledge each year of the minimums and maximums necessary for swine diet formulation.
In this column, we have discussed some conditions that look like deficiencies in swine, but too much of a nutrient, such as copper and zinc, can cause environmental concerns, too.
Although swine diets are better than ever before, nutrition must still be considered in diagnosing production concerns in today's swine units.