The Vitamin a Requirement of the Young Pig

Abstract

Four experiments involving 226 pigs carried out over a period of two years have been described. These pigs were from sows reduced considerably in their vitamin A reserves by previously feeding a ration low in vitamin A. They were weaned at 7 days of age and the requirement for vitamin A was estimated in the first 8 weeks of life. Several criteria of adequacy were investigated and their sensitivity, precision and validity discussed. These criteria were weight gain, feed efficiency, bloood plasma and liver vitamin A, and cerebrospinal fluid pressure. Other functions also studied will be discussed in later papers. Of the three criteria (weight gain, plasma vitamin A and spinal fluid pressure), the plasma response was the most precise and the weight gain the least as measured by the lambda value of Bliss (in György, '51). However, the minimum point of normality was most readily detectable in the spinal fluid pressure response and this point occurred at a similar dietary intake of vitamin A in all experiments (600 to 800 I.U.). The liver vitamin A accumulation, estimated on fewer animals, was found to be extremely sensitive and very consistent between experiments. The minimum requirement of the young pig for a stabilized source of vitamin A palmitate on a dry carrier was judged to be 800 I.U./lb. of feed under the conditions which existed. Normality in weight gain occurred at as low as 100 I.U./lb. of feed. Acute paralysis of the hindquarters was the most striking deficiency symptom.