Effect of dietary calcium concentrations during gestation and lactation in the sow on milk composition and litter growth

This study evaluated the effects of diets containing varying amounts of Ca on milk composition and litter characteristics of sows. Yorkshire sows were fed one of the following diets: low Ca (.38%; n = 5), standard Ca (.75%; n = 5), or high Ca (1.12%; n = 4). Diets were fed from d 42 of gestation to d 42 of lactation. Milk was collected on d 7 ± 1, 21 ± 1, and 42 ± 1 of lactation. Lactose was greater (6.4%, P < .05) in milk from sows fed low Ca than in those fed standard (5.5%) or high (5.8%) Ca, but only on d 7 of lactation. No treatment effect or time × treatment interaction was detected for total protein or casein concentrations. Calcium increased (P < .05) over time irrespective of treatment. There was an increase (P < .05) in ADG on d 7 in pigs from high-fed (.28 kg) and low-fed sows (.20 kg) compared with those from standard-fed sows (.13 kg). In conclusion, body Ca is so physiologically regulated that minor dietary alterations have little overall effect on milk composition. Alterations in ADG for pigs, especially from sows fed high Ca, warrant further investigation.