Reports that the presence of persistent organic pollutants in fat may affect fatty acid metabolism prompted this research aiming to study the relationship between the contents of γ-HCH and DDT, DDE, DDD, and ΣDDT, and fatty acid composition of milk fat. The material consisted of 50 samples of cow and mare milk, collected in 2015. Ludwicki’s and the Röse-Gottlieb and IDF Standard methods were used to prepare the samples. Statistical analyses were conducted using Statistica 12.0. There was a negative correlation between the content of γ-HCH and C16:1, C17:1, C18:1c9, C18:1c9c12, and ΣMUFA in cow milk fat and C13:0, C14:0, and C10:1 in mare milk fat. A positive correlation was observed between γ-HCH and C6:0 to C12:0, C14:0, C18:1t16, and ΣSFA in cow milk fat, and between this compound and C14:0iso, C16:1, C17:1, C18:1c9,11, and ΣMUFA in mare milk fat. A negative correlation between the contents of ΣDDT and C16:1, C17:1, C18:1c9,11,13 and ΣMUFA in cow milk fat and C16:0iso, C17:0, and C18:3 in mare milk fat was noted. A positive correlation was found between the contents of ΣDDT and saturated and polyunsaturated fatty acids and ΣSFA and ΣPUFA in cow milk fat, and C18:2c9c12 in mare milk fat. The correlation between the content of selected organochlorine compounds and the composition of fatty acids in cow and mare milk fat indicates the strong influence of these environmental pollutants on the nutritional value of milk fat.

Gastric pH was monitored in neonatal foals from birth to 3 months of age. Background pH decreased, especially during the first week of life. Milk had complex effects that depended on pH prior to sucking, confounded by the age of the foal: nearly neutral background pH tended to be acidified after milk intake; moderately acid background pH tended to be neutralized; low background pH was only slightly increased by milk. Absolute magnitude of the effects of milk decreased with age. Existence of a proulcerative intragastric environment in preweaning foals is postulated, but this must be considered in the context of what probably is a multifactorial pathogenesis.

Concentrations of amino acids in plasma and whole blood in response to 10 hours of food deprivation were determined in healthy 2-day-old foals (n = 8) and were compared with control values in foals of the same age (n = 8) allowed free access to suckle. In addition, response of concentrations of amino acids in plasma to 15 minutes of free-access suckling was determined at the end of the 10-hour period in both groups. Response of 13 amino acids in plasma of food-deprived foals was significantly (P < 0.05) different, compared with that in control foals. Concentrations of 3 amino acids (alanine, glycine, and phenylalanine) in plasma increased significantly (P < 0.05), whereas concentrations of 7 amino acids (asparagine, citrulline, histidine, ornithine, proline, tryptophan, and tyrosine) in plasma decreased significantly (P < 0.05) during food deprivation. Response of concentrations of 2 amino acids (glycine and histidine) in whole blood was significantly (P < 0.05) different from that in plasma of food-deprived vs control foals. Refeeding of food-deprived foals resulted in significantly (P < 0.05) different responses for concentrations of all but 2 amino acids (cystine and taurine) in plasma, compared with responses in controls. Changes in concentrations of amino acids in plasma and whole blood of foals in response to food deprivation are similar to those in foals with septicemia and in children with grade 1 or 2 kwashiorkor. The significantly different response of food-deprived foals to refeeding may be attributable to increased protein intake or altered physiologic state.

The effects of 2 liquid formula diets differing in protein source were evaluated in orphan foals. The response of 7 foals fed a diet containing casein as the protein source, and 6 foals fed a diet containing a combination of whey and casein, was compared with the response in a reference group of 8 mare-raised foals. Orphaned foals were fed 150 kcal/kg of body weight/d, divided into 6 equal feedings of 25 kcal/kg. Formula intake was comparable among the experimental groups, and foals fed the liquid formula diet grew as well as mare-raised foals. There was no difference among groups in mean daily body weight gain, wither height, heart girth, body temperature, pulse, respiration rate, capillary refill time, or skin tenting. Insulin and blood glucose concentrations increased in both groups of foals fed formula diets, returning to prefeeding values within 4 hours. Differences among groups were found for serum alkaline phosphatase, alanine transaminase, cholesterol, creatinine, and glucose values; all other serum chemical values were comparable among groups. Plasma amino acid determinations revealed that arginine and ornithine were significantly lower in foals in both experimental groups than in reference foals, suggesting that arginine may have been the limiting amino acid in these diets. Diarrhea developed in foals in all treatment groups, but in most cases was self-limiting. These results suggest that the protein source of liquid formula diets may be less important in foals than in infants.

Epidermal growth factor (EGF)-like activity was measured in mares' colostrum and milk by radioreceptor assay. Milk samples were collected from 22 mares 1 or more times during early lactation. Samples of colostrum were taken after parturition and before the foal first suckled (presuckle), within 6 hours after the foal first suckled (postsuckle), and on days 1, 2, 4, and 8 of lactation. In the 5 mares from which milk samples were obtained at each sampling time, presuckle colostral mean EGF-like activity (17.8 ng/ml) was greatest (P < 0.05). The mean values for EGF-like activity at all other sampling times were not significantly different from each other (postsuckle colostrum, 9.7 ng/ml; day 1, 9.6 ng/ml; day 2, 8.5 ng/ ml; day 4, 8.0 ng/ml; day 8, 7.8 ng/ml).