Effects of reducing dietary amino acid density and stocking density on growth performance, carcass characteristics, meat quality, and occurrence of white striping in broiler chickens

Abstract

A 49-day trial was conducted to determine the impact of dietary amino acid ( AA ) density and stocking density ( SD ) on growth performance, carcass traits, meat quality, and white striping ( WS ) occurrence in broiler chickens. Two hundred eighty-eight Ross 308 male broilers consisting of 6 replicate cages with 8 broilers per replicate were used. Treatments were arranged in a 3 × 2 factorial and consisted of 3 AA densities (normal, 10, or 20% lower than normal) and 2 different SD (high 35 kg/m 2 or low 26 kg/m 2 ). Breasts were classified as normal, moderate, and severe for WS. Data were analyzed as a completely randomized design using the GLM procedure. Decreasing AA density decreased overall growth performance, carcass, breast yields, and fillet dimensions linearly, while leg and rib cage yields increased linearly ( P < 0.01). High SD decreased hot carcass, breast, wings, and rib cage weights in birds fed normal AA diets ( P < 0.05). High SD increased the length of breast fillet ( P < 0.05). Cooking loss, breast lightness (L∗), and redness (a∗) at 48 h postmortem increased linearly with decreasing AA density, while ultimate breast pH ( pH u ) and nitrogen content decreased linearly ( P < 0.05). The occurrence of normal, moderate, and severe WS fillets was 45.3, 49.1, and 5.6%, respectively. As the dietary AA density decreased, the occurrence of no WS breast fillets increased linearly, whereas the occurrence of moderate WS fillets and mean WS score decreased linearly ( P < 0.05). SD did not affect the occurrence of WS. Severe WS fillets were heavier and had higher cranial thickness, pH u , and fat content and lower yellowness ( P < 0.05), but water-holding capacity, nitrogen content, L∗, and a∗ value did not differ among different WS scores. Taken together, WS occurrence and severity increased with higher growth rate. Growth depression created by lowering dietary AA density regardless of SD resulted in a decrease in mean WS score, but it also compromised the growth and meat quality.

Environmental Stress in Chickens and the Potential Effectiveness of Dietary Vitamin Supplementation

“…High density stocked birds had reduced tibia quality compared to low-density stocked ones (Wang et al, 2020). In addition, Wang et al (2014) observed a reduction in drip loss of broilers breast muscle, triggered by high SD, while Pekel et al (2020) reported that the length of breast filet was significantly increased among stressed broilers. Drip loss can show quality deviations as the volume of drip loss is an indicator of oxidative stress in muscles (Wang et al, 2014).…”

Intermittent dilution of dietary digestible lysine lowers the incidence of white striping by suppressing the growth, lipid synthesis, and muscle damage in broiler chickens

“…Nutrient requirements of Ross 308 broiler chickens recommended by Aviagen (Huntsville, AL, USA, 2019) were used as benchmark. Control group was fed starter (days 0-10), grower (days [11][12][13][14][15][16][17][18][19][20][21][22][23][24], finisher (days [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], and withdrawal (days [40][41][42][43][44][45][46][47][48][49] diets according to the recommendations. Remaining groups received diets as follows:…”

“…¶ Each kilogram contained: manganese (as manganese oxide 62%) 150 000 mg; iron (as iron sulfate monohydrate 31%) 120 000 mg; zinc (as zinc oxide 72%) 120 000 mg; copper (as copper sulfate pentahydrate 25%) 12 000 mg; iodine (as calcium iodide 62%) 3000 mg; selenium (4.5%) 225 mg; molybdenum (as sodium molybdate 39%) 750 mg; calcium carbonate 13% (as carrier). starter (days 0-10), grower (days [11][12][13][14][15][16][17][18][19][20][21][22][23][24], finisher (days 25-39), and withdrawal (days [40][41][42][43][44][45][46][47][48][49].…”

“…Unlike this, slowdown of growth trajectory in broiler chickens has shown to reduce the occurrence of WS with their own pros and cons. Researchers have made several attempts to slow down the growth of broiler chickens through quantitative feed restriction, 8 and continuous and intermittent restriction of nutrients like metabolizable energy (ME), 9,10 digestible lysine (dLys), 11‐13 and amino acid (AA) densities 10,14 . Although quantitative feed restriction lowers the development of WS, it has been deemed impractical owing to the absence of equipment in many regions of the world and persistently poor growth performance.…”

“…Researchers have made several attempts to slow down the growth of broiler chickens through quantitative feed restriction, 8 and continuous and intermittent restriction of nutrients like metabolizable energy (ME), 9,10 digestible lysine (dLys), [11][12][13] and amino acid (AA) densities. 10,14 Although quantitative feed restriction lowers the development of WS, it has been deemed impractical owing to the absence of equipment in many regions of the world and persistently poor growth performance. Similarly, continuous restriction of dietary nutrients greatly affects the growth of broiler chickens while lowering the incidence of WS.…”