ABSTRACT:The effects of sex and slaughter age on growth, feed intake, carcass composition and meat quality attributes of musculus longissimus lumborum were investigated in Charolais × Simmental bulls (n = 12) and heifers (n = 12) reared and finished under identical management conditions. The animals entered the experiment at similar age (251 days) and were slaughtered at 14 or 18 months of age. Bulls gained more rapidly (P < 0.001), consumed more dry matter daily (P < 0.05), and had a higher killing-out proportion (P < 0.05). The sex × slaughter age interaction was significant (P < 0.01) for feed conversion ratio, which deteriorated markedly more in heifers than in bulls as slaughter age increased. Bulls produced leaner carcasses with a higher proportion of total meat (P < 0.001). While bulls contributed to high-priced meat by a higher proportion of meat from the shoulder (P < 0.01), heifers had higher proportions of meat from the rump and loin (P < 0.05). Older animals were generally fatter and their carcasses contained lower proportions of high-priced meat (P < 0.01) and bones (P < 0.05). Bulls exhibited lower contents of dry matter (P < 0.001), protein (P < 0.05) and intramuscular fat (P < 0.001), and a higher content of collagen (P < 0.001) in musculus longissimus lumborum than hei-fers. The meat from heifers was assessed by the sensory panel as more tender and, when aged for 11 days, more acceptable than the meat from bulls. Older animals obtained higher scores for beef flavour intensity (P < 0.01), tenderness (P < 0.001), juiciness (P < 0.05), and overall acceptance (P < 0.001).

Compared with beef, venison from two widely farmed deer species was superior in nutrient composition, thus offering potential benefits for human consumption, and it received higher scores for most of the sensory attributes examined.

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Breed effects on live weight gain, slaughter characteristics and carcass composition were compared in Aberdeen Angus, Charolais, Hereford and Simmental bulls. The experiment extended over 2 years and involved totally 96 animals. The target slaughter live weights were determined 550 kg for earlier maturing breeds Aberdeen Angus and Hereford and 630 kg for later maturing breeds Charolais and Simmental. Charolais and Simmental gained more rapidly (P < 0.05) than Aberdeen Angus while Hereford were intermediate. Hereford had lower (P < 0.05) dressing percentage than the other breeds. Percentages of grade I meat were significantly higher (P < 0.05) in Charolais and Simmental. The highest percentage of separable fat was recorded in Hereford (P < 0.05). Charolais and Simmental had lower (P < 0.05) thickness of subcutaneous fat over MLLT than Aberdeen Angus and Hereford. The later maturing bulls generally tended to achieve higher live weight gains during the experiment, produced less fat and had higher percentage of meat from high priced joints in comparison with earlier maturing animals.

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Aberdeen Angus (AA), Charolais (CH), Simmental (SI), and Hereford (HE) bulls were used in two fattening experiments with the objective of determining breed differences in chemical composition, sensory characteristics, and fatty acid profile of m. longissimus thoracis et lumborum. The target slaughter live weights were set at 550 kg for earlier maturing breeds AA and HE and 630 kg for later maturing breeds CH and SI. Intramuscular lipid contents were higher in AA and HE (P < 0.05) than in CH and SI, but cholesterol contents were similar among the breed groups. The highest content of dry matter was found in HE (P < 0.05), while AA had the lowest protein content (P < 0.001). Meat from AA generally received the highest scores for different sensory characteristics (odour, flavour, texture, and juiciness). Concentrations of stearic acid (C18:0) in total muscle lipids were lower in SI than in CH (P < 0.05), while total saturated fatty acids were lower in SI compared to CH (P < 0.001) and AA (P < 0.05). CH had less oleic acid (C18:1-n9c) and total monounsaturated fatty acids than AA (P < 0.05), SI and HE (P < 0.01). Concentrations of linolenic acid (C18:3-n3) were highest in AA (P < 0.01).

ABSTRACT:The aim of this study was to estimate allelic and genotypic frequencies of five DNA markers that are positional and functional candidates for milk production traits in Czech Fleckvieh cattle. In addition, we evaluated the association of these markers with milk production traits and breeding values for milk production traits and also estimated linkage disequilibrium (LD) between two markers within the prolactin (PRL) gene. As part of this study, 505 Czech Fleckvieh cows were genotyped. The markers in proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A), secreted phosphoprotein (SPP1), cytochrome P450 family 11 subfamily B hydroxylase (CYP11B1), and the two polymorphisms in the prolactin gene (PRL) showed evidence of segregation in our study. The PPARGC1A polymorphism was associated with milk yield, milk fat and protein traits. The polymorphism in SPP1 was significantly associated with milk protein percentage. The CYP11B1 polymorphism showed positive associations with milk composition traits and breeding values for milk yield, milk fat, and protein traits. Both polymorphisms within the PRL gene were associated with milk yield, milk fat and milk protein yield (individually and grouped). Linkage disequilibrium between the two polymorphisms in PRL was not observed. In conclusion, all markers examined in this study are important markers for milk production traits in Czech Fleckvieh cattle, and both markers within the PRL gene should be evaluated in future research.