Impact of dietary calcium and phosphorus on sow reproductive performance and bone development in piglets
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The concern for restricted movement for sows housed in stalls during gestation has prompted the swine industry to move towards group housing. Additionally, the emphasis on increasing sow productivity has led to a continuous need for re-evaluation of nutrient requirements for sows, including minerals. Unfortunately, the majority of studies that examined the role of dietary Ca and P for sows were older (early 1970s to 1990s), and may not be applicable to the modern, prolific sow, particularly those housed in group housing systems. Two studies were conducted to determine the effects of dietary Ca and P for gestating sows on reproductive performance, bone metabolism and fetal skeletal development. The objective of the first study was to determine if the recommended levels of dietary Ca and P are adequate for sows housed in groups, and thus have potential for increased mobility. A total of 180 multiparous sows and gilts were assigned to 1 of 6 treatments. Treatments, arranged as a 3 × 2 factorial, included main effects of dietary Ca:P; 0.70:0.55 (% as fed, Control); 0.60:0.47 (-15 % 1998 NRC); 0.81:0.63 (+ 15 % 1998 NRC) and housing; stalls or groups. Sows were fed 2.3 kg/d from wk 4 to 5 of gestation until 2 wk prior to farrowing when the allotment was increased to 3.0 kg/d. Serum samples were collected at the start of the trial and on d 100 of gestation, and both serum and milk samples were collected at mid-lactation and prior to weaning. Neither diet nor housing had an effect on total number of piglets born, ADG from birth to weaning, or weaning weight (P > 0.10). The number of piglets born live and birth weight were unaffected by diet (P > 0.10) but improved in group housing relative to stalls (P < 0.05). In late gestation, group-housed sows fed the low Ca diet had reduced serum Ca (diet × housing interaction; P = 0.02) and the greatest reduction in serum P level was also observed in group-housed sows fed the low Ca diet (diet × housing interaction; P = 0.04). Osteocalcin (OC), and pyridinoline (PYD) markers of bone formation and resorption respectively, were unaffected by diet or housing (P > 0.10). The second study was conducted to determine the influence of Ca and P intake by young, gestating sows on the growth and skeletal development of their developing piglets and if smaller birth-weight piglets are at greater risk from mineral insufficiency during gestation. A total of 30 sows were randomly assigned to 1 of the 3 dietary Ca:P treatments used in the first study. Sows were fed their daily rations in 1 allotment as described in Exp. 1. Only sows farrowing litters with 12 piglets or more remained on trial. At birth, the smallest and a normal-sized piglet from each litter were euthanized, and the left femur extracted for peripheral quantitative computed tomography (pQCT) scanning. Serum samples were collected at birth and prior to weaning. Number of piglets born, body weight (BW) at 3 d of age, and piglet ADG were unaffected by treatment (P > 0.10). At birth, the highest serum Ca level was seen in the small piglets from sows fed a high Ca diet (diet × size interaction; P = 0.04) however, at weaning, this value had the smallest deviation from the initial value (diet × size interaction; P = 0.02). Femurs of piglets from sows fed the low Ca diet had the highest cortical density (P = 0.03) and piglet size had no effect on cortical density (P > 0.10). Bone ash %, ash Ca %, ash P %, and serum bone markers were unaffected by diet or piglet size (P > 0.10). Results from these studies suggest that the recommended level of dietary Ca and P as prescribed by NRC 1998, and thus for NRC 2012, is adequate for high-producing sows of modern genetics, whether housed in stalls or groups. Moderate changes in Ca and P intake by young, gestating sows, does not negatively affect the growth or skeletal development of their piglets.
DegreeMaster of Science (M.Sc.)
DepartmentAnimal and Poultry Science
SupervisorBeaulieu, Angela D.
CommitteeKontulainen, Saija; Christensen, David
Copyright DateApril 2015