Modyfikujący wpływ roślinnych dodatków paszowych na użytkowość mięsną i ekspresję wybranych genów u królików w zależności od wieku i płci

Abstract

The aim of the study was to determine the effect of feed additives (algae, soybean, and sunflower oil) used in the rabbit feed on: growth indices and slaughter traits, pH, colour, texture, chemical composition, fatty acid profile and oxidative stability (TBARS) of the meat as well as FTO and FABP4 genes expression in the meat’s intramuscular fat (m. longissimus lumborum), depending on the age and sex. The experimental material consisted of Termond White rabbits (n = 160, 80 females and 80 males). Animals were weaned on the 35th day of life, and housed in metal cages arranged in batteries (4 rabbits of the same sex in a cage). From weaning to 12 or 18 weeks of age, the rabbits were fed pellets ad libitum. Animals in the control group (C) received non-supplemented pellets throughout the experiment. In the other groups, the pellet contained 1% algae (A), 3% sunflower oil (OS), and 3% soybean oil(SO).The experimental diets were formulated to have similar protein and energy content. Diets were balanced by lowering the proportion of other feed components. The total share of all components remained at 100%. The results indicate that 3% vegetable oils (soybean or sunflower) supplementation of diets for growing rabbits leads to an increase of body weight and improvement of some of the slaughter traits, while 1% addition of algae to the feed causes deterioration of body weight and slaughter traits. The effect of oil additive depends on the animals’ age. Supplementation of the rabbits’ diet with algae (1%) or sunflower and soybean oils (3%) led to an increase in the dressing percentage of rabbits slaughtered at 18 weeks of age (approx. 3%), but had no effect on the dressing percentage of rabbits slaughtered at 12 weeks of age. Feeding pellets with either 3% vegetable oils or 1% algae additive to the rabbits did not significantly change the chemical composition of the meat. Protein content increased and intramuscular fat content decreased with age, while ash and water content were similar. The feed additives significantly differentiated meat acidity without deteriorating meat quality. Diet modification has not affected negatively meat colour. 24 h after the slaughter, the colour of rabbit meat was similar across the studied feeding groups. Correlation between diet and rabbits’ age was found. Meat texture (hardness, springiness and chewiness) of all rabbit groups slaughtered at 12 weeks of age was similar, and the shear for cewas greater in rabbits fed pellets with algae and soybean oil. At 18 weeks of age, rabbit meat from experimental groups had lower hardness and chewiness, compared to meat of the animals from the control group. Meat shear force was higher in the control group, and from algae-supplemented group. The correlation between diet and age was also found. The use of 3% vegetable oils or 1% algae as feed additives significantly reduced meat oxidative stability. Soybean or sunflower oil (3%) usedas feed additives favourably modified the fatty acid composition of intramuscular fat. Polyunsaturated fatty acids (PUFA) content was increased, including linoleic acid, and PUFA/MUFA ratio was improved. The content of these acids decreased with age. The use of algae (1%) as a feed additive resulted in positive effect on the increase of n-3 fatty acid content (EPA and DHA) in meat intramuscular fat. Algae supplementation improved pro-health properties of meat, with low n-6/n-3 acid ratio (2.5), indicating that diet modification may affect the fatty acid composition of rabbit meat. The influence of diet and age on FTO and FABP4 gene expression in meat intramuscular fat (m. longissimus lumborum) was found. FTO and FABP4 gene expression increased with age and was the highest in the group of rabbits with 1% algae supplementation in the diet. The effect of rabbits’ gender on growth, slaughter traits, meat quality and gene expression in rabbits was not observed. In conclusion, the use of natural feed additives, such as sunflower, soybean oil or algae, can improve the nutritional value of rabbit meat, without changing its chemical or physical properties, and therefore the meat can serve as functional food, with properties beneficial to human health. The results obtained in this study also indicate that the expression of FTO and FABP4 genes in rabbit muscles is regulated by dietary factors and age, which, in addition to cognitive significance, has practical implications for improving technological and dietary quality of rabbit meat.