Calf Note Examines Whether Skim Milk Improves Calf Performance

Calf Note #286, edited by calf-nutrition specialist Jim Quigley, reviews the role of skim milk powder in replacers used for artificially reared dairy calves. The note examines whether a higher share of skim milk produces measurable gains in average daily weight gain, feed conversion or health when formulas are properly balanced.

Skim milk supplies casein, a protein that reacts with rennet and stomach acid in the abomasum. It forms a firm clot, which can slow gastric emptying and release amino acids gradually into the small intestine. Whey proteins, by contrast, remain soluble and pass through the glandular stomach more rapidly before being absorbed in the intestinal tract.

The review describes the long-standing view that the absence of a casein clot could increase the risk of digestive problems and nutritional diarrhoea. It also considers how low-heat processing and improved whey concentrates have prompted renewed examination of that assumption. The technical comparison focuses on the biological quality of the proteins rather than on the nominal proportion of skim milk shown on a product label.

Across the comparative trials discussed in the note, calves receiving replacers with adequate levels of crude protein, fat and metabolizable energy did not consistently gain a statistically significant advantage from higher skim milk inclusion. Faecal consistency, enteric events and voluntary intake of starter feed were likewise reported as broadly comparable between calves receiving moderate or low skim milk proportions and those fed casein-rich formulas, provided that alternative proteins had not been damaged by excessive heat during drying.

The formulation choice also affects the cost of milk replacer. Skim milk powder generally commands a substantial premium over cheese-making whey derivatives on international agricultural-input markets. Using more skim milk can therefore raise the price per tonne of finished replacer. The note says that paying this premium on the assumption that it will produce better-prepared replacement heifers may increase rearing costs without a quantifiable benefit by weaning.

Calf Note says that producers and nutrition advisers should assess the replacer’s overall biological quality, solubility and preservation of amino acids. It identifies early colostrum management, an adequate daily supply of usable solids—including total protein and energy—and strict hygiene in calf facilities as factors in performance before and after weaning. The source of the technical note is Calf Notes.