Dietary Supplementation of Magnesium Sulfate during Late Gestation and Lactation Affects the Milk Composition and Immunoglobulin Levels in Sows

Effects of negative dietary cation-anion difference and calcidiol supplementation in transition diets fed to sows on piglet survival, piglet weight, and sow metabolism

Diets that provide a negative dietary anion cation difference (DCAD) and supplement with a vitamin D metabolite 25-OH-D3 (calcidiol) may increase calcium availability at parturition, and enhance piglet survival and performance. This factorial study assessed the effects of DCAD, calcidiol (50 µg/kg), and parity (parity 1 or >1) and their interactions. Large White and Landrace sows (n = 328), parity 1 to 8 were randomly allocated in blocks to treatment diets from day 103 of gestation until day 3 postfarrow: 1) negative DCAD without calcidiol (negative DCAD + no CA), n = 84, 2) negative DCAD with calcidiol (negative DCAD + CA) n = 84, 3) positive DCAD without calcidiol (negative DCAD + no CA), n = 81, and 4) positive DCAD with calcidiol (positive DCAD + CA), n = 79. Negative DCAD diets were acidified with an anionic feed (2 kg/t) and magnesium sulfate (2 kg/t). All treatment diets contained cholecalciferol at 1,000 IU/kg. Dry sow diets contained 14.8% crude protein (CP), 5.4% crude fiber (CF), 0.8% Ca, and 83 mEq/kg DCAD. Treatment diets 1 and 2 contained 17.5% CP, 7.3% CF, 0.8% Ca, and -2 mEq/kg DCAD. Treatment diets 3 and 4 contained 17.4% CP, 7.4% CF, 0.8% Ca, and 68 mEq/kg DCAD. Before farrowing, all negative DCAD sows had lower urine pH than all sows fed a positive DCAD (5.66 ± 0.05 and 6.29 ± 0.05, respectively; P < 0.01); urinary pH was acidified for both DCAD treatments indicating metabolic acidification. The percentage of sows with stillborn piglets was not affected by DCAD, calcidiol, or parity alone but sows fed the negative DCAD + CA diet had a 28% reduction in odds of stillbirth compared to the negative DCAD + no CA diet and even lesser odds to the positive DCAD + CA diet. At day 1 after farrowing, blood gas, and mineral and metabolite concentrations were consistent with feeding a negative DCAD diet and that negative DCAD diets influence energy metabolism, as indicated by increased glucose, cholesterol, and osteocalcin concentrations and reduced nonesterified free fatty acids and 3-hydroxybutyrate concentrations. In the subsequent litter, total piglets born and born alive (14.7 ± 0.3 and 13.8 ± 0.3 piglets, respectively; P = 0.029) was greater for positive DCAD diets compared to negative DCAD diets; and there was an interaction between DCAD, calcidiol, and parity (P = 0.002). Feeding a negative DCAD diet influenced stillbirth, subsequent litter size, and metabolic responses at farrowing. More studies are needed to define optimal diets prefarrowing for sows.

Dietary Supplementation with Different Types of Potassium and Magnesium during Late Gestation and Lactation Modulates the Reproductive Performance, Antioxidant Capacity, and Immune Function of Sows

The objective of this study was to investigate the effects of dietary supplementation with different types of potassium and magnesium on the reproductive performance, antioxidant capacity, and immunity of sows. Forty-five Landrace × Yorkshire sows at the late gestation stage (85 d) were randomly assigned to three groups (n = 15). Sows in the control group (CON), potassium chloride and magnesium sulfate group (PM), and potassium-magnesium sulfate group (PMS) were fed with a basal diet, a basal diet supplemented with magnesium sulfate (0.20%) and potassium chloride (0.15%), or a basal diet supplemented with potassium-magnesium sulfate (0.45%), respectively. The results showed that dietary supplementation with PMS did not yield significant effects on the reproductive performance compared with the CON group (p > 0.05). However, it significantly elevated the level of insulin-like growth factor 1 (IGF-1) in plasma and immunoglobulin A (IgA) in colostrum (p < 0.05). Furthermore, PMS significantly augmented the activities of catalase (CAT) and superoxide dismutase (SOD) while reducing the levels of malondialdehyde (MDA) in comparison to the CON group (p < 0.05). Compared with the PM group, the PMS group significantly reduced the incidence rate of intrauterine growth restriction (IUGR) (p < 0.05) and significantly decreased the concentration of the proinflammatory cytokine (TNF-α) level in plasma (p < 0.05). These results indicated that dietary supplementation with PMS during late gestation could enhance sows' antioxidant capacity and the IgA level in colostrum. These findings will provide a theoretical reference for the use of magnesium and potassium in sow production to improve sows' health.

Do calcium and magnesium deficiencies in reproducing ewes contribute to high lamb mortality?

High lamb mortality continues to be a significant economic and welfare problem within the Australian sheep industry, with 20–30% of lambs born in commercial flocks dying mostly within 3 days of birth. Clinical hypocalcaemia and hypomagnesaemia cause ewe mortality, and, subsequently, either fetal or lamb death, but it is not known whether subclinical deficiencies of calcium (Ca) and magnesium (Mg) compromise lamb survival. This review considers the potential mechanisms through which Ca and Mg deficiencies may influence lamb survival, and factors influencing the risk of deficiency. Pastures grazed by lambing ewes may be marginal in calcium (Ca; &lt;4 g/kg DM) and magnesium (Mg; &lt;0.9 g/kg DM) but also have a high dietary cation–anion difference (&gt;12 meq/100 g DM) and high concentrations of potassium (K; &gt;30 g/kg DM) and nitrogen. In young cereal crops, sodium concentrations are also often low (&lt;0.9 g/kg DM). This combination of minerals and other nutrients creates an imbalance in supply and increases susceptibility to acute Ca (hypocalcaemia) and Mg (hypomagnesaemia) deficiency. Calcium is required for smooth muscle function and has a direct role in uterine contraction, so may influence the duration of parturition. Low Ca and Mg intake both influence insulin release and sensitivity, low Mg results in poor glycaemic control and insulin resistance by impairing both insulin secretion and its action on peripheral tissues, also potentially altering the duration of parturition as well as risk of metabolic disease. Magnesium is also a neuroprotectant that slows the neuronal damage during hypoxia and has been linked with thermogenesis in offspring and increased immunoglobulins in colostrum. These functions indicate potential importance in improving the ease of parturition and improved ability of the newborn lamb to thermoregulate and survive after birth. Subclinical Ca and Mg deficiencies commonly occur in 20% of lambing ewes grazing temperate pastures, so further studies are warranted to investigate whether correction of these deficiencies can improve lamb survival.

Calcium and magnesium status of pregnant ewes grazing southern Australian pastures

During pregnancy, ewes graze pastures that may be marginal in calcium (Ca) and magnesium (Mg), and may also be low in sodium (Na) and high in potassium (K), with a high dietary cation–anion difference. Such pastures may increase susceptibility to hypocalcaemia and hypomagnesaemia, leading to lamb losses. Clinical hypocalcaemia and hypomagnesaemia do occur in Australian sheep; however, it is unknown whether subclinical forms of these disorders compromise ewe or lamb health and survival. The present study monitored the Ca and Mg status of ewes in late pregnancy, so as to evaluate the risk of subclinical mineral disorders in ewes grazing typical southern Australian pastures. Calcium and Mg concentrations in pasture, ewe plasma and urine were monitored in 15 flocks in southern Australia. Mineral concentrations in pasture did not indicate a widespread risk of Ca or Mg deficiency; however, urinary pH and Ca and Mg concentrations in the plasma and urine of the pregnant ewes were not entirely consistent with the expectations from pasture analysis. Urine pH was above 7 on all properties and 87.5% of properties had a mean Ca in urine below the adequate concentration of 1 µmol/mosmol. The mean plasma Ca concentration was below adequate (<90 mg/L) on only one farm but five farms had more than 20% of ewes with below adequate Ca in plasma. In addition, although average farm concentrations of plasma and urine Mg indicated adequate Mg status of the ewes (>18 mg/L), more than 20% of ewes on six farms had below adequate concentrations of plasma Mg. Only one-third of the farms had 100% of ewes measured with adequate concentrations of plasma Ca (4/15) or Mg (5/15). The mineral concentrations in pre-lambing blood and urine samples suggested that a significant number of animals grazing southern Australian pastures during winter may be at risk of subclinical hypocalcaemia and hypomagnesaemia.

Prevalence of constipation and its influence on post-parturient disorders in tropical sows

The present study aimed to investigate the prevalence of constipation and its influence on farrowing duration and the evidence of post-parturient disorders in tropical sows and to evaluate the efficacy of a laxative supplementation during gestation and around farrowing on the incidence of constipation. Two experiments were performed in a commercial swine herd in Thailand. In experiment 1, the prevalence of constipation was determined in 96 gestating sows. Subsequently, 62 of them (64.6 %), with a severe to moderate degree of constipation, received 20 ml of a laxative for 3 days during gestation. In experiment 2, constipation score was determined in sows before, during, and after farrowing. A total of 98 sows were randomly allocated to one of two groups: the treatment group (n = 48) received 20 ml of a laxative for 3 days before farrowing, and the control group (n = 50) did not receive any laxative. Rectal temperature, appetite score, incidence of postpartum dysgalactia syndrome (PDS), and vaginal discharge score was determined for 4 days. In experiment 1, supplementation of laxative reduced the proportion of sows with moderate to severe constipation (P < 0.05). In experiment 2, sows with moderate to very severe constipation had a 28-min longer duration of farrowing than sows with normal faeces. Constipation in sows on the day of farrowing resulted in reduced appetite on day 1 postpartum (P = 0.008). The incidence of sows with fever on day 1 postpartum was two times higher in sows with constipation than in sows with normal faeces (36.2 and 16.7 %, respectively; P = 0.041).