Dietary strategies to alleviate high-stocking-density-induced stress in broiler chickens – a comprehensive review

Abstract

Abstract. Stocking broilers at a high density has been a strategy to optimize the area of the cage and hence increase the efficiency of broiler production. If the environmental (microclimate) conditions and rearing management are not properly managed, stocking broilers at a high density may, however, result in stressful conditions that are harmful for the production, health and welfare of broilers. To ameliorate these unfavorable effects of overcrowding stress, dietary interventions have been conducted. Probiotics, prebiotics, synbiotics, plant-derived products, vitamins, propolis, amino acids, fatty acids, etc. have been supplemented in diets to deal with the harmful impact of stress induced by a high stocking density of broilers. This review covers the detrimental effects of overcrowding-induced stress on broiler development and attempts to ameliorate those negative effects by dietary interventions.

Effect of Dietary Chlorogenic Acid on Growth Performance, Antioxidant Function, and Immune Response of Broiler Breeders under Immune Stress and Stocking Density Stress

“…Immune stress caused by LPS and stress from high stocking density are two major concerns in poultry production and these two stresses greatly impair the productive and reproductive performance of chickens with grave economic consequences. Studies have shown that compromised growth rate, feed intake, and FCR of chickens have been associated with immune stress and high-density stress [ 20 , 21 , 22 , 23 ]. Similarly, our results indicate that LPS injection and high stocking density significantly decrease body weight and feed the intake of broiler breeders.…”

“…Our results are consistent with others’ findings that the GSH content decreases after LPS treatment [ 28 , 29 ], but in this study, changes in GSH under high stocking density were not observed. Because some research results showed that overcrowding induced oxidative stress in broilers, as represented by a decrease in GSH level in the liver [ 23 ], the variations in GSH level could be correlated with the different stocking densities we used or different species of broilers. In the present study, CGA increased the GSH content in the intestines of immune-stressed broiler breeders, in agreement with Shi [ 30 ], who found that CGA significantly increased GSH levels in liver tissue and reduced oxidative stress.…”

Dietary organic acids ameliorate high stocking density stress-induced intestinal inflammation through the restoration of intestinal microbiota in broilers

“…Global chicken meat production has been growing in recent decades and reaches 99.10 million tons in 2021 [ 1 ]. To meet market supply and achieve high efficiency, the high stocking density (HSD) rearing is commonly applied in broiler production to maximize the area of the cage [ 2 ]. The HSD is defined based on the number of chicks per square meter as well as the weight of birds per square meter in broiler production.…”

The effect of using acidified turmeric on some productive parameters and intestinal bacterial counts in broilers at high stocking density pens

“…The high environmental temperature (33°C–35°C, at day) and humidity (85–90%, at day) throughout the study appeared to aggravate the stress caused by the high stocking density, and hence turmeric and acidified turmeric powder seemed too hard (ineffective) in compensating the stress on chickens in this present study. Note that temperature and humidity are the two factors that can exacerbate stress due to overcrowding in broilers [ 16 ].…”

“…A previous study reported that overcrowding increased red blood cell values in broilers [ 17 ]. Owing to the role of red blood cells in transporting oxygen, the elevated red blood cells were assumed to be due to an increased oxygen demand for metabolic activities in broilers in response to stress [ 16 ]. However, this did not appear to be the case in our investigation, as no significant variations in erythrocytes, hemoglobin, or hematocrits were seen between high- and normal-density stocked birds receiving the basal feed.…”