Acidogenic mineral additions increased Ca mobilization in prepartum sows

Evaluation of calcium to phosphorus ratio in spot urine samples as a practical method to monitor phosphorus intake adequacy in sows

The objective of this study was to evaluate the reliability of using Ca to P ratio measured in spot urine samples to assess P intake adequacy in gestating and lactating sows. A total of 36 sows were fed one of six concentrations of dietary total P (0.40%, 0.48%, 0.56%, 0.64%, 0.72%, and 0.80%) from day 7.5 ± 1 after breeding until the end of lactation (day 26.6 ± 1). Dietary Ca to P ratio was maintained constant across treatments at 1.25:1. Total 24-h urine samples were collected in mid- and late gestation (days 77.1 ± 2 and 112.4 ± 1), and early and late lactation (days 4.5 ± 1 and 18.2 ± 1). In parallel to 24-h collections, spot urine samples were collected at three different times (early morning, late morning, and late afternoon) in late gestation and late lactation. Urine Ca and P concentrations were measured and Ca to P ratio was calculated. Sows were classified as P-adequate or P-deficient according to dietary P intake. Urine Ca to P ratio was greater in sows fed P-deficient diets than sows fed P-adequate diets (P < 0.001). Receiver operating characteristic (ROC) curves were used to determine the cutoff values for urine Ca to P ratio to predict P intake adequacy. Three different categories of P intake were defined according to urine Ca to P ratio: deficient, adequate, and excessive. The area under the ROC for Ca to P ratio was 0.88 (95% CI 0.81 to 0.95). Best cutoff value of urine Ca to P ratio was 1.5 (sensitivity 94% and specificity 68%) to identify sows fed P-deficient diets and 0.5 for P-excessive diets (sensitivity 82% and specificity 82%). A strong relationship between Ca to P ratio in 24-h and spot urine samples was determined (r = 0.93, P < 0.01), independent of physiological state and collection time of spot samples (adjusted-R2 = 0.86, P < 0.01). The degree of agreement between spot and 24-h urine for P intake adequacy, assessed by Cohen's weighted kappa analysis, was substantial (0.78, 95% CI 0.69 to 0.88). We conclude that urinary Ca to P ratio provides a reliable prediction of the adequacy of P intake in reproducing sows. Urinary Ca to P ratio measurements in random spot urinary offers a practical method to determine dietary P adequacy.

Supplementary Tryptophan Fed to Sows Prior to and after Farrowing to Improve Piglet Growth and Survival

Simple Summary

Pre-weaning mortality is a significant economic and welfare issue for the Australian pig industry. Tryptophan can increase serotonin and melatonin production. Serotonin can decrease stress and indirectly increase calcium, which may improve sow health. Meanwhile, melatonin may decrease stillbirths and improve piglet viability at birth and, in turn, increase survival to weaning. This study determined whether feeding 0.16%, 0.42% or 0.56% tryptophan (per kg of feed) to sows during late pregnancy until seven days of lactation could improve piglet survival and viability to weaning and increase the levels of calcium and melatonin in sows. Supplementing tryptophan at levels of 0.42 and 0.56% increased piglet survival compared to no supplementation but did not have an effect on piglet viability. Furthermore, tryptophan supplementation did not increase sow melatonin and calcium levels compared to 0.16%. Further research is required to understand how tryptophan may improve piglet survival, particularly through sow maternal behaviour, and if 5-hydroxytryptophan (the form of tryptophan that directly converts to serotonin and melatonin) would further improve piglet survival.

Abstract

Tryptophan indirectly increases plasma calcium levels, which may improve sow health, and melatonin production, which may improve piglet survival when supplemented during late gestation and lactation. It was hypothesised that tryptophan would increase piglet survival and increase sow circulating melatonin and calcium. Seventy-two multiparous (Landrace x Large White) sows were allocated to either control (0.16% tryptophan; n = 24), low tryptophan (0.42%; n = 24) or high tryptophan (0.56%; n = 24). Piglet viability measures consisted of weights, behaviour, meconium staining, rectal temperature, blood glucose and serum immunoglobulin G concentration. Blood samples collected from sows were analysed for melatonin (two daytime and three night-time samples; n = 17) and calcium (two samples pre- and post-farrowing; n = 14). Both tryptophan treatments increased piglet survival compared to the control group (p < 0.001). Tryptophan had no effect on piglet viability (p > 0.05) and no effect on sow plasma melatonin and calcium concentrations compared with the control group (p > 0.05) except at 21:00 when low tryptophan sows had higher melatonin concentration compared with high tryptophan (p = 0.011). Further research to understand the mediating effects of tryptophan (particularly 5-hydroxytryptophan) on piglet survival, including sow behaviour, is warranted.

Evaluation of increased fiber, decreased amino acids, or decreased electrolyte balance as dietary approaches to slow finishing pig growth rates

In swine production, pig movement restrictions or packing plant closures may create the need to slow growth rates of finishing pigs to ensure they remain at a marketable body weight when packing plant access is restored. Although dietary formulations can be successful at slowing pig growth, precision is needed regarding how to best formulate diets to achieve growth rate reductions. Thus, the objective was to evaluate three dietary experimental approaches aimed at slowing growth rates in finishing pigs. These approaches consisted of either increasing neutral detergent fiber (NDF), reducing essential amino acids, or reducing the dietary electrolyte balance through the addition of acidogenic salts. A total of 94 mixed-sex pigs (72.4 ± 11.2 kg BW) across two replicates were individually penned and assigned to 1 of 8 dietary treatments (n = 11-12 pigs/treatment): 1) Control diet representative of a typical corn-soybean meal-based finisher diet (CON); 2) diet containing 15% NDF from soybean hulls (15% NDF); 3) diet containing 20% NDF from soybean hulls (20% NDF); 4) diet containing 25% NDF from soybean hulls (25% NDF); 5) diet formulated as per CON but with 50% of the soybean meal replaced with corn (89% Corn); 6) diet containing 97% corn and no soybean meal or synthetic amino acids (97% Corn); 7) diet containing 2% anhydrous calcium chloride (2% CaCl2); and 8) diet containing 4% anhydrous calcium chloride (4% CaCl2). Over 28 d, pig body weights and performance were recorded weekly. At d 28, all pigs were ultrasound scanned and switched to the CON diet to evaluate compensatory gain from d 28 to 35. Overall, increased NDF did not impact any growth performance parameter (P > 0.05). Amino acid restriction reduced average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F) linearly (linear P < 0.001). Similarly, ADG, ADFI, and G:F were linearly reduced with increased CaCl2 inclusion (linear P < 0.001). ADG differed during the compensatory gain period (P < 0.001), with 4% CaCl2-fed pigs having a 47% increase in ADG compared with CON-fed pigs. Conversely, 15% and 25% NDF-fed pigs had reduced ADG compared with CON-fed pigs during the compensatory gain period. Gain efficiency differed from day 28 to 35 (P < 0.001), with 4% CaCl2-fed pigs having a 36% increase in G:F compared with CON-fed pigs. Altogether, these data demonstrate that both amino acid restriction and CaCl2 inclusion are effective at slowing pig growth, albeit at greater inclusion rates.

Lowering dietary cation-anion difference increases sow blood and milk calcium concentrations

A study was conducted to evaluate the effects of feeding an acidogenic diet with a low dietary cation-anion difference (DCAD) on acid-base balance, blood, milk, and urine Ca concentrations of sows during lactation. A total of 30 multiparous sows (parity: 4.5 ± 2.9, Smithfield Premium Genetic, Rose Hill, NC) were allotted to 1 of 2 dietary treatments: CON (control diets were corn-soybean meal based with a calculated DCAD of 170 and 226 mEq/kg during late gestation and lactation, respectively) or ACI (acidogenic diets had a DCAD 100 mEq/kg lower than the control diets). The lower DCAD was achieved by the addition of an acidogenic mineral. The DCAD was calculated as mEq (Na + K - Cl)/kg diet. Sows had a daily access to 2-kg feed from day 94 of gestation to parturition and ad libitum access to feed during lactation. Blood and urine pH and Ca, serum macrominerals, serum biochemistry, Ca-regulating hormones, and milk composition were measured. Sows in ACI had a lower (P < 0.05) blood pH than sows in CON at day 1 of lactation. Sows in ACI had a lower (P < 0.05) urine pH at day 108 of gestation, days 1, 9, and 18 of lactation compared with sows in CON. Sows in ACI had greater (P < 0.05) concentrations of serum total Ca at days 1 and 18 of lactation than sows in CON. There was a greater (P < 0.05) concentration of colostrum Ca in ACI than in CON. There was no difference in urine Ca concentration between treatments during lactation. Concentrations of parathyroid hormone and 1,25-dihydroxycholecalciferol were not different between treatments at either day 1 or 18 of lactation. Sows in ACI tended to have a smaller (P = 0.086) concentration of total alkaline phosphatase in serum at day 18 of lactation compared with sows in CON. At day 1 of lactation, the concentration of serum Cl in ACI was greater (P < 0.05) than that in CON. Feed intake, BW loss, and litter performance were not different between treatments. Collectively, feeding an acidogenic diet with a low DCAD to sows can induce a mild metabolic acidosis at farrowing, reduce the urine pH consistently, and increase serum total Ca and colostrum Ca concentrations during lactation but without altering the parathyroid hormone and 1,25-dihydroxycholecalciferol levels during lactation.