Grass valorisation and muscular characteristics of blonde d'Aquitaine steers

Abstract

-The blonde d'Aquitaine breed, the males of which are traditionally raised as young steers in intensive systems, is spreading beyond its region of origin. In pasture regions these males could be introduced into more extensive grazing systems. The purpose of this study is to assess the capability of these animals to valorise forage resources and also the characteristics of the carcasses produced and of the muscles concerned when considering meat tenderness. The study used young weaned bulls reared as beef animals and slaughtered at 33 months of age (n = 22 and 24). These beef animals use 2 very different types of pasture during the pasturing seasons (April-November). During the first winter period of rearing the Blonde d'Aquitaine show a lower ingestion of forage (5.8 kg dry matter . 100 kg -1 life weight vs. 7.5 kg dry matter . 100 kg -1 life weight) and lower growth than the Charolais (1 150 g . d -1 vs. 1 400 g . d -1 ). At pasture, the activity of the animals is similar (380 minutes at pasture, 52 bites per minute for speed of ingestion). At slaughter, at the same body weight (695 kg), the Blonde d'Aquitaine have a greater weight of muscle (+ 9%, 335 kg of muscle vs. 308 kg). The Blonde d'Aquitaine have a more glycolytic muscular metabolism (1 497 µmol . min -1. g -1 vs. 1351 µmol . min -1. g -1 ), a higher proportion of fast, IIB fibers (63.6% vs. 58.8%) and less collagen (3.7 µg d'OH-prol . mg -1 of DM vs. 5.2 µg d'OH-prol . mg -1 of DM). These results show that animals of blonde d'Aquitaine breed provide a good valorisation of forage and grass and that under these breeding conditions, they produce muscles with favourable characteristics for production of tender meat.

Development of image analysis tool for the classification of muscle fibre type using immunohistochemical staining

“…CSA rises significantly (p \ 0.05) from 1,484 to 3,628 lm 2 for the LT and from 1,717 to 4,263 lm 2 for the ST. These results are fully consistent with those we obtained in 33-month-old bulls of the same breed (Listrat et al 2001). The relative expressions of the MyHC isoforms obtained with the electrophoresis method are compared to those obtained with the histological method (Fig.…”

Consequences of selection for higher growth rate on muscle fibre development in cattle

“…The same results were observed in DM muscles, from foetal to adult; DM muscles contain a higher proportion of fast glycolytic fibres (Gagnière et al, 1997Deveaux et al, 2001). Similar characteristics have also been observed in Blonde d'Aquitaine steers with enlarged muscle mass, as compared with Charolais steers (Listrat et al, 2001). These results are in accordance with those of Soike and Bergmann (1998) obtained in chicken bred for meat compared to egg production.…”

Adult steers for beef production: breed effect on animal performance, retail yield and carcass quality

“…In this sense, in spite of the absence of significant differences in slaughter weight, Limousin carcass provided a higher percentage of First category cuts than Brown Swiss, and in general, higher amounts of saleable meat, and for this reason Limousin breed could be more advantageous for steer production. Our results are supported by a study of Listrat et al (2001) in Charolais and Blonde d'Aquitaine steers slaughtered at 33 months. These authors reported that Blonde d'Aquitaine showed a higher yield for carcass and muscle than Charolais steers without significant differences in slaughter weight.…”