USE OF ALTERNATIVE FEED MIXES FOR THE REA RING OF YOUNG BOARS

Three metabolism trials were conducted to evaluate differences in mass digestibility of nutrients between eight breeding boars of the Large White x Holland Yorkshire (paternal line) breeds at the average live w eight of 48 kg, 73 kg and 98 kg. The young boars received the feed mix OPO (rearing of breeding pigs) containing soybean meal (12%) and grai ns (78.7%) and the feed mix OPO/H containing pea (10%) and rapeseed 00 meal (2.5%), and grains (69.2%). The animals of control groups receiv ed the feed mix OPO, the experimental animals were fed the mix OPO/H. Crude protein content in the feed mix OPO was higher by 13.5 g, which equals 7.7% in comparison with the feed mix containing pea. The latter mix had the fiber content higher by 16.7 g, which makes 29.2% against the mixture with soybean meal. The coefficients of apparent mass dige stibility of nutrients in the 1st metabolic trial at the average live weight of 48 kg (80.03 and 79.08% for dry matter, 80.98 and 80.22% for crude protein, 63.91 and 72.40% for fat, 23.31 and 26.20% for fiber, 87.91 and 87.46% for nitrogen-free extract, 43.81 and 4133% for ash, 8 2.49 and 81.63% for organic matter) were insignificantly different in the particular groups (P > 0.05). Tabs. III and IV show the determined coefficients of nutrient digestibility in the 2nd and 3rd trial at th e average live weight of young boars 73 and 98 kg. There were insignif icant differences in nutrient digestibility between the groups when ev aluated by t-test (P > 0.05). Comparison of the metabolism trials cond ucted at the given live weight showed the best efficiency of the feed mix with soybean meal in the boars at the average live weight of 73 kg (highest digestibility of dry matter, crude protein, nitrogen-free ex tract, ash). The highest digestibility of fiber and fat was determined in the highest weight category. Nutrient digestibility in the feed mi x with pea was variable in the particular balance periods (fiber, fat) . There were small differences in the digestibility of dry matter, nit rogen-free extract, ash and organic matter between the metabolism tria ls. Crude protein digestibility tended to increase with growing live w eight of young boars. Overall evaluation of nutrient digestibility (Fi g. 1) in the particular groups for the feed mix containing soybean mea l (control group) indicated the higher digestibility of dry matter (81 .19% and/or 79.64%), crude protein (83.55% and/or 82.35%) and nitrogen -free extract (88.59% and/or 87.67%). Higher digestibility of fiber (3 0.44% and/or 26.19%) and fat (69.14% and/or 62.21%) was determined whe n the animals received the feed mix containing pea (experimental group ). The difference in the digestibility of organic matter (83.33% and/o r 83.88%) and ash (43.85% and/or 43.36%) was however minimum between t he groups. There were insignificant differences in the coefficients of nutrient digestibility (P > 0.05) for all the basic nutrients. Overal l evaluation of the indicators of nitrogen utilization, i.e. nitrogen uptake and its retention, indicates increases in their values with the growing five weight of young boars. Nitrogen retention from its uptak e and biological value of proteins tended to decrease their values wit h the growing live weight of young boars. There were no statistically significant differences in the indicators of fattening performance and carcass value, even though certain trends in favor of the feed mix wi th soybean meal were observed. A significant difference was determined only in the spare rib weight (P < 0.05) in favor of the control group . The above results demonstrate that both tested mixtures are usable ( alternatively) for the rearing of breeding young boars, both in indivi dual test and in usual rearing system.