Impact of feeding whole Upland cottonseed, with or without cracked Pima cottonseed with increasing addition of iron sulfate, on milk and milk fat composition of lactating dairy cattle

• Published in: Animal feed science and technology 2005-12, Vol.123 (3-4), p.667-685
• Main Authors: McCaughey, K.M., DePeters, E.J., Robinson, P.H., Santos, J.E.P., Taylor, S.J., Pareas, J.W.
• Format: Article
• Language: English
• Subjects: alfalfa; Animal productions; biohydrogenation; Biological and medical sciences; Cottonseed; cow feeding; dairy cows; fatty acid composition; Fatty acids; feed additives; Feed and pet food industries; feed concentrates; feed processing; Food industries; Fundamental and applied biological sciences. Psychology; Gossypium barbadense; Gossypium hirsutum; hay; Holstein; iron; Iron sulfate; milk composition; Milk fat; milk quality; milk yield; parity (reproduction); Phospholipids; Pima; rumen fermentation; Terrestrial animal productions; triacylglycerols; Upland; Vertebrates
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2005.08.001

Primiparous and multiparous lactating Holstein cows were fed one of four diets containing either whole Upland cottonseed (WCS) or cracked Pima cottonseed (CrP), the latter with two levels of iron sulfate. Effects of supplemental iron sulfate, and the impact of substitution of 2/3 of the WCS with CrP, on milk and milk fat composition were determined. All diets contained 490 g/kg concentrate, 100 g/kg cottonseed and 410 g/kg chopped alfalfa hay on a dry matter basis. The cottonseed portion of the WCS diet contained only WCS and the other three diets contained 67 g/kg CrP and 33 g/kg WCS. Diets containing CrP were supplemented with 0, 250 or 500 mg Fe (from iron sulfate)/kg of diet. Four primiparous and four multiparous cows were used in a double 4 × 4 Latin square design experiment with 28-day periods. Yields of milk and milk components were not affected by substitution of WCS with CrP cottonseed, but they declined linearly with increasing level of dietary iron sulfate. Milk composition was not affected by either dietary treatment, but the fatty acid (FA) composition of milk fat varied to a modest extent. Increases in C18:2 and C18:3, with a decrease in C18:1 n11 trans, when WCS was replaced with CrP suggests less perturbation of ruminal biohydrogenation, and increased ruminal escape of dietary FA, in cows fed CrP. Although the linear decrease in the unsaturated FA in milk fat, and decrease in the amount of long chain FA in milk fat triglycerides, with supplemental iron sulfate indicates that it may have affected ruminal biohydrogenation of dietary FA to some degree, the modest extent of these changes suggests that it was small and unlikely to be of biological or practical relevance.