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.

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).

This study was conducted to evaluate the body weights and measurements of 86 Gascon calves and their dams. The effects of the course of parturition, parity of the dams, sex of the calves, and live- or stillborn calves were analysed. Phenotypic correlations between different measurements and calf birth weight as well as the course of parturition were calculated. Internal pelvic measurements were significantly associated with the occurrence of assisted calvings and stillborn calves. Primiparous cows had a smaller pelvic area, lower live weight, and more frequent difficulty in calving compared to older cows. A higher incidence of difficult calvings was observed in bull-calves due to their higher (<I>P</i> < 0.001) birth weight. High and significant correlation coefficients were determined between the birth weight and body measurements of the calves as well as between the calf birth weight and the course of parturition (<I>r</i> = 0.34; <I>P</i> < 0.01). Negative correlations (<I>r</i> = –0.21 to –0.30) were calculated between the internal pelvic measurements of the cows and the course of parturition score. It was concluded that the internal pelvic measurements of the dam and the size and shape of the calf were the factors influencing the course of parturition in this study to the largest extent.

A total of thirty-four Czech Fleckvieh (CF), Charolais (CH) and Charolais × Czech Fleckvieh (CH × CF) bulls with an average weight of 284 kg were included in the experiment and fed ad libitum two mixed diets: MS (based on maize silage) and LCS (based on legume-cereal and lucerne silages) with different concentrations of dietary energy until slaughter at the target live weight of 600 kg. The CF bulls consumed more dry matter (DM) of feed daily than the CH bulls (P < 0.05) and gained weight less efficiently than the CH × CF and CH animals (P < 0.01) during the entire experiment. The killing-out percentage was lower in the CF than in the CH × CF and CH (P < 0.05). The CH bulls received a higher score for carcass conformation and a lower score for carcass fatness (P < 0.01) than the CF bulls, had lower proportions of kidney and cod fat (P < 0.01) than the CH × CF and CF bulls, and produced the highest percentage of high-priced meat (P < 0.05) and the lowest percentage of separable fat (P < 0.001). The bulls on the MS diet were younger than the others at the end of the experiment (P < 0.01), gained weight more rapidly (P < 0.001), consumed less DM (P < 0.001) daily, utilized nutrients more efficiently over the entire experimental period (P < 0.001), and had a higher proportion of internal fat than the LCS bulls. It can be concluded that purebred CH bulls were superior to the other breed groups in most of the traits observed. The intensive diet based on maize silage increased average daily gains, reduced the time needed to achieve the target slaughter weight, and improved the feed efficiency of bulls.

Abstract. The objective of this study was to determine the effects of breed and a diet containing linseed on the growth and carcass composition characteristics of heifers. A total of 48 Limousin (LI) and Charolais (CH) heifers with an average weight of 270 kg were assigned to two diets containing either extruded linseed (LIN) or no supplemental oilseed (CON). The target slaughter weight was set at 500 kg. The diet had no effect on any of the observed production traits. The CH heifers had higher live weight gains (P<0.001) and a lower feed conversion ratio (P<0.001). The LI heifers had a higher dressing percentage (P<0.001), higher meat to bone ratio (P<0.001), greater m. longissimus lumborum et thoracis area (P<0.05), and produced more internal and carcass fat (P<0.05). It was concluded that purebred LI heifers grew less rapidly and less efficiently but produced heavier carcasses with a more favourable meat to bone ratio compared to purebred CH heifers.