Slaughter value and meat quality of broiler chickens fed with rations containing a different share of pea seed meal.

BACKGROUND

The study aimed to evaluate the effect of feed rations with a different share of pea seed meal on the slaughter value, physicochemical and organoleptic characteristics of breast muscles in broiler chickens.

METHODS

A growth experiment was carried out involving 120 Ross 308 broiler chickens allocated randomly to three feeding groups each consisting of 40 birds of both sexes. Each group was divided into five subgroups each consisting of eight chickens. Until the 21st day of life the birds were fed ad libitum with loose starter rations, and from day 22 to day 35 with grower rations based on corn, post-extraction soybean meal, soy oil and mineral and vitamin additives. In starter and grower rations in experimental groups (II and III) post-extraction soybean meal was replaced with pea seed meal in the amount of 10% and 20% (II) and 15% and 25% (III). On day 35 the chickens were slaughtered, and their meat was analysed. Samples of breast muscles were collected in order to determine their dietary value and physical and sensory characteristics.

RESULTS

Pea seed meal in feed rations for experimental chickens had no influence on the body weight and dressing percentage, but it increased their muscularity and decreased the fattening grade in comparison to chickens fed with rations in which the only protein feed was post-extraction soybean meal. The breast muscles of chickens receiving feed rations containing pea (group II and III, respectively) contained significantly (P ≤ 0.05) less crude fat - about 30% and 27% less. Pea added to feed rations significantly (P ≤ 0.05) increased (by about 19% and 27%) the share of linoleic acid C18:3n-3 in the lipids of the breast muscle. The lowest (P ≤ 0.05) content of saturated fatty acids (23.43%) and at the same time the highest (P ≤ 0.05) content of unsaturated fatty acids (76.42%) was noted in the breast muscles of chickens receiving feed rations containing 15/25% of pea seed meal. More hypocholesterolemic acids (DFA) and less hypercholesterolemic acids (OFA) were found in the muscles of chickens from groups II and III (P ≤ 0.05). After 24 hours of cooling the carcasses, it was demonstrated that the pH in the muscles of chickens fed with rations containing pea was significantly (P ≤ 0.05) higher than in chickens from the control group. Irrespective of the share of pea in the diet, the muscles of these birds were of a significantly lighter colour (51.37 and 52.45 vs 44.18). In addition, muscles of birds from groups II and III were characterised by less (P ≤ 0.05) redness (a*) and yellowness (b*). The values of psychometric colour saturation (C*) lower by 29% and 48% were identified in the muscles of chickens from groups II and III in comparison to the muscles of birds fed with corn and soy rations. The breast muscles of chickens fed with rations containing a smaller share of pea were characterised by the highest (P ≤  0.05) water holding capacity (WHC) in comparison to others. The muscles of chickens from group III scored the highest for all flavour traits, but a statistically significant difference was noted only for tenderness.

CONCLUSIONS

Considering the slaughter value and quality of the breast muscles of chickens, the results provide a basis for recommending pea seed meal as a partial substitute for post-extraction soybean meal in feed rations for broilers. An improvement in muscularity and fattening grade was noted in comparison to carcasses of birds receiving corn and soy rations. In addition, the breast muscles of chickens fed rations with peas contained less intramuscular fat with a more favourable, healthy fatty acids profile (significantly more C18:3n-3, PUFA and DFA). In terms of the physical properties of muscles no deterioration in their quality was noted depending on the feed. Also, the results of sensory evaluation provide a basis for recommending peas as a component of broiler feed rations.