Effects of supplemental zinc amino acid complex on gut integrity in heat-stressed growing pigs

Abstract

Heat stress (HS) jeopardizes livestock health and productivity and both may in part be mediated by reduced intestinal integrity. Dietary zinc improves a variety of bowel diseases, which are characterized by increased intestinal permeability. Study objectives were to evaluate the effects of supplemental zinc amino acid complex (ZnAA) on intestinal integrity in heat-stressed growing pigs. Crossbred gilts (43 ± 6 kg BW) were ad libitum fed one of three diets: (1) control (ZnC; 120 ppm Zn as ZnSO 4 ; n = 13), (2) control + 100 ppm Zn as ZnAA (Zn220; containing a total of 220 ppm Zn; n = 14), and (3) control + 200 ppm Zn as ZnAA (Zn320; containing a total of 320 ppm Zn; n = 16). After 25 days on their respective diets, all pigs were exposed to constant HS conditions (36°C, ∼50% humidity) for either 1 or 7 days. At the end of the environmental exposure, pigs were euthanized and blood and intestinal tissues were harvested immediately after sacrifice. As expected, HS increased rectal temperature ( P ⩽ 0.01; 40.23°C v. 38.93°C) and respiratory rate ( P ⩽ 0.01; 113 v. 36 bpm). Pigs receiving ZnAA tended to have increased rectal temperature (P = 0.07; +0.27°C) compared with ZnC-fed pigs. HS markedly reduced feed intake (FI; P ⩽ 0.01; 59%) and caused BW loss (2.10 kg), but neither variable was affected by dietary treatment. Fresh intestinal segments were assessed ex vivo for intestinal integrity. As HS progressed from days 1 to 7, both ileal and colonic transepithelial electrical resistance (TER) decreased ( P ⩽ 0.05; 34% and 22%, respectively). This was mirrored by an increase in ileal and colonic permeability to the macromolecule dextran ( P ⩽ 0.01; 13-and 56-fold, respectively), and increased colonic lipopolysaccharide permeability ( P ⩽ 0.05; threefold) with time. There was a quadratic response ( P ⩽ 0.05) to increasing ZnAA on ileal TER, as it was improved ( P ⩽ 0.05; 56%) in Zn220-fed pigs compared with ZnC. This study demonstrates that HS progressively compromises the intestinal barrier and supplementing ZnAA at the appropriate dose can improve aspects of small intestinal integrity during severe HS.

A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari lambs1

“…Furthermore, the fact that heat-stressed sheep grew faster than the pair-fed controls agrees with recent pig experiments (Sanz-Fernandez et al, 2012Pearce et al, 2013). This growth differential is even more energetically atypical considering that HS is thought to increase maintenance costs in most animals (Kleiber, 1961) including sheep (Ames et al, 1971).…”

“…This finding agrees with a recent report indicating that heatstressed pigs had increased efficiency of converting dietary nutrients into body mass (Johnson et al, 2014). The obvious differences in growth performance between HS lambs and PFTN controls in our experiment and in others (Sanz Fernandez et al, 2012;Pearce et al, 2013;Mahjoubi et al, 2015) implies that HS markedly influences the energetics of tissue accretion. In contrast to our hypothesis, feeding a gluconeogenic precursor did not ameliorate the decreased ADG during HS.…”

Effects of a supplement containing multiple types of gluconeogenic precursors on production and metabolism in Holstein bull calves during heat stress

“…However, interpreting production data needs to be conducted with care as the experiment likely did not have enough animals to detect treatment differences, especially because the variation of growth increased during HS (standard deviation of ADG was 0.41, 0.75, 0.62 and 0.68 kg/d for wk -1, 1, 2 and 3 respectfully). Regardless, the improvement in rate of gain (Figure 3) as HS progressed implies that calves were acclimating to their environment and this agrees with our previous results in growing lambs (Mahjoubi et al, 2014), calves (O'Brien et al, 2010) and pigs Sanz-Fernandez et al, 2013).…”

Short-term exposure to heat stress attenuates appetite and intestinal integrity in growing pigs1

“…Additionally, HS pigs have altered metabolic responses (reduced heat production) and feeding behavior compared to thermoneutral-reared pigs (Renaudeau et al, 2013). We have also reported that HS reduced feed intake in pigs and the deleterious consequences of HS may also be partially mediated by its effects on intestinal integrity (Pearce et al, 2013a;Sanz Fernandez et al, 2014).…”