Assessing the Effects of Probiotic Supplementation on Growth Performance, Goblet Cell Density, and Carcass Quality in Intensive Pig Finishing Systems Under Heat Stress Conditions

Project Abstract

This study assessed the impact of dietary probiotic supplementation on growth performance, gastrointestinal mucosal integrity as indicated by goblet cell density, and carcass quality in intensively reared pigs subjected to heat stress during the finishing phase. A randomized complete block design was employed with four dietary treatments a control basal diet, and basal diets supplemented with 0.5, 1.0, and 2.0 g probiotic/kg feed, each replicated across six pens and 12 pigs per pen. The probiotic blend comprised Lactobacillus spp., Bifidobacterium spp., Enterococcus faecium, and a Saccharomyces cerevisiae strain, selected for heat tolerance and multi-strain synergistic potential. Heat stress was simulated by maintaining ambient temperatures between 30–34°C with high humidity during the day for six weeks, modeling commercial conditions. Growth performance metrics included average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR), and final body weight. Goblet cell density was quantified in ileal and jejunal mucosa using histomorphometry, alongside mucin staining to evaluate mucosal protective capacity. Carcass quality parameters encompassed hot carcass weight, backfat thickness, loin eye area, lean meat percentage, pH24, and intramuscular fat content. Blood samples were analyzed for cortisol, glucose, and non-esterified fatty acids as indicators of stress and metabolic status. Additionally, expressions of tight junction proteins (occludin, claudin-1) and inflammatory markers (TNF-?, IL-6) in intestinal tissues were measured by qPCR to elucidate gut integrity and inflammatory responses. Statistical analysis utilized mixed-effects models with pen as a random effect and treatment, time, and their interactions as fixed effects. Where applicable, repeated measures were analyzed, and post hoc comparisons were performed using Tukey’s test (p < 0.05). Results indicated that probiotic supplementation linearly improved ADG and FCR, with the 1.0 g/kg dose yielding optimal performance under heat stress (p < 0.05). A significant dose-dependent increase in goblet cell density and mucin area was observed in both the jejunum and ileum, suggesting enhanced mucosal defense against thermal-induced disruptions. Carcass analysis showed higher hot carcass weight and lean meat percentage in probiotic-treated groups, with reduced backfat thickness at 1.0 g/kg and 2.0 g/kg doses (p < 0.05). pH24 values were more favorable, indicating improved post-mortem glycolytic stability, while intramuscular fat did not differ significantly among treatments. Blood cortisol and glucose levels were reduced in probiotic groups, aligning with attenuated physiological stress and improved energy balance. Molecular data revealed upregulation of occludin and claudin-1 and downregulation of TNF-? and IL-6 in probiotic-supplemented pigs, corroborating gut barrier reinforcement and moderated inflammatory responses. Overall, probiotic supplementation at 1.0 g/kg feed demonstrated the most consistent benefits across growth performance, intestinal morphology, carcass quality, and stress physiology under heat stress, with dose-dependent effects suggesting a threshold beyond which additional supplementation yields diminishing returns. The findings support the strategic use of multispecies probiotics as a practical intervention to mitigate heat-induced performance losses in intensive pig finishing systems, underpinning recommendations for dietary inclusion rates, and highlighting mechanisms involving enhanced mucosal defense, improved gut integrity, and moderated systemic stress. Further research is warranted to explore long-term effects across different genetic lines and varying climate conditions.

Project Overview

What This Project Is About

---

A straightforward study that looks at whether adding probiotics to pig diets can improve how fast pigs grow, how their gut lining functions, and the quality of the meat, especially when pigs are raised in hot, challenging conditions.

---

---

The Problem It Addresses

---

Pigs raised in hot environments often grow slower, have stressed guts, and produce lower-quality meat. There is a need for affordable ways to support pig health and performance without relying only on medicines. Probiotics offer a potential, natural solution, but evidence in heat-stress finishing systems is mixed.

---

---

Objectives of the Project

---

1. Evaluate whether probiotic supplementation improves growth rate and feed efficiency under heat stress.
2. Assess changes in goblet cell density in the gut lining as an indicator of gut health.
3. Examine carcass quality traits such as fat, meat color, and tenderness.
4. Identify practical probiotic doses that show benefits without extra costs.

---

---

What You Will Do Step by Step

---

1. Review existing literature on probiotics, gut health, and heat stress in pigs.

2. Design a feeding trial with control and probiotic groups under simulated heat stress.

3. Monitor growth, feed intake, and health indicators during finishing.

4. Collect gut tissue samples to measure goblet cell density.

5. Assess carcass traits after slaughter and standard meat quality tests.

6. Analyze data using basic statistics to compare groups.

7. Interpret results and discuss practical implications for farmers.

---

---

Expected Outcome

We expect probiotics to improve growth performance, support gut health as shown by goblet cell density, and enhance some carcass quality traits under heat stress, offering a cost-effective strategy for pig producers.