Fatty Acid Composition And Quality Of Meat From Hybrid Simmental Bulls

Experiment1Quality assessment of corn stover silage with different additivesSilaMax200(silage fermentation probiotics) and SilaMixII (mineral salt carrier+probiotics mixture+GXC), developed by the Sino-US Sustainable GrasslandDevelopment Research Center, was used in production of corn stover silage todetermine the efficacy of the products in improving silage quality. Conventionalnutrients, pH, lactic acid and volatile fatty acids were determined on days1,7,14, and21of fermentation. The results showed that dry matter losses were reduced during thecorn stover silage fermentation period, in both silage treatments and crude proteinpercent was higher in Max200after21days compared to an untreated control. Crudefat content, as well as calcium and phosphorus content in the additive treatments weresimilar to the control silage. Silage pH declined more rapidly in Max200treatmentcompared to control pH declined to a lower level in MixII by21days compared tocontrol or Max200. Use of MixⅡand Max200increased the lactic acid content andthe ratio of lactic acid to acetic acid, and reduced butyric acid.Experiment2Fatty acid composition and quality of meat from hybridSimmental bullsFatty acid composition was determined for perirenal and intramuscular fat fromthe longissimus dorsi in54Simmental cross bull finished on a ration of concentrateand corn silage and slaughtered at different weights.Saturated fatty acid (SFA) content of the perirenal fat was significantly higherthan the longissimus dorsi muscle fat, while the polyunsaturated fatty acid (PUFA)content of the longissimus dorsi muscle fat was significantly higher than the perirenalfat (P <0.01). The longissimus muscle fat has a lower content of SFA, a higher totalunsaturated fatty acids(UFA) content, a balanced PUFA/SFA value, and containshigh levels of the beneficial fatty acids, DHA and CLA, and therefore has a desirablenutritional value. However, the n-6/n-3value of longissimus muscle is higher than thedietary recommended value of4. Longissimus dorsi muscle fatty acid content was significantly influenced by thecorn stover silage with different additives, but perirenal fat fatty acid content was lessaffected. In the longissimus dorsi muscle, MixII group had a lower n-6/n-3value thanthe control group and Max200group, and contained higher MUFA content. However,PUFA content and P/S value of the MixII group was significantly lower than thecontrol group and the Max200group.Slaughter weight had some effect on fatty acid composition of Simmentalcrossbred cattle. In general, the over500kg group had the higher nutritional value offatty acid, with more CLA and γ-linolenic acid (P <0.05) in longissimus musclecompared with450kg~500kg group.There were no significant differences in Warner-Bratzer shear force, pH, pressloss and cooking loss based on the corn stover silage additive treatments (P>0.05).During the aging period, shear force value at day1was significantly higher than days7and14. Press loss increased from day1to day7and decreased from day7to day14of aging. Meat pH decreased from day1to day7then slightly increased from day7today14of aging. There was a correlation of percentage intramuscular fat (IMF) withtenderness at7days of aging and marbling score. Oleic acid content had a significantpositive correlation with percentage IMF, while linoleic acid, n-3PUFAs and n-6PUFAs each had significant negative correlations with percentage IMF.