Growth Performance and Meat Quality of Purebred Bulls Reared under Intensive Production Systems

Growth ability and meat performance are of great economic importance in beef cattle. Therefore, breed comparison experiments are needed to provide valuable information on the suitability of different beef breeds for different production and market conditions (Zahrádková ​et al., 2010).
       
Beef cattle breeds represent various biological types, well adapted to various environments and production systems representing different feed, climate, land resources and marketing situation. Breed diversity can be used to fit the genetic resources quickly to production and market requirements (Jakubec et al., 2003).
       
Over the recent decades we have witnessed changes in the utilisation of various breeds in beef production, with intensive selection targeting different traits in different breeds of cattle. Selection of breeds of medium frame sizes puts emphasis on their growth rate rather than calving ease or low body weight at birth, which is the case in the selection of large-frame-size cattle (Núnez-Dominguez et al., 1993). Lighter breeds tend to demonstrate genetic trends for higher growth rates, causing a gradual reduction in size differences between breeds (Sullivan et al., 1999). Williams et al., (2010) showed that the Angus genetic trend for weaning and yearling weight from the 1980s to the present is 1.5 times greater than that of the Limousin breed during the same time period.
       
Although previous studies have evaluated the growth performance and meat quality of breeds used for beef production, there is a need to re-examine such differences between breeds in the light of the genetic shifts that have taken place (Clarke et al., 2009). Therefore, the aim of the present study was to compare the growth performance and meat quality of young Red Angus, Salers and Limousin bulls.

The material comprised 30 bull calves of Red Angus (RA), Salers (SL) and Limousin (LM) breeds (10, 8 and 12 animals in each breed, respectively). All calves were derived from the same herd and were raised together under the same conditions. The Red Angus cows were sired by polled bulls from Canada and the USA, the Salers cows by Canadian bulls and the Limousin cows by bulls from France. The calves born in February and March remained with their dams until October, being fed entirely on maternal milk and grazing during this period. After weaning, the bulls were kept indoors and fattened intensively to 18-19 months of age and a minimum body weight of 550 kg. The fattening bulls were fed concentrate (0.5 kg/animal), crushed barley (3 kg/animal), maize silage (15 kg/animal) and hay ad libitum. The animals were weighed at birth and at weaning, as well as when they reached the final body weight. The parameters studied were 210-d body weight and daily gains from birth to weaning and to finishing, as well as from weaning to finishing.

The finished bulls were slaughtered after 12-hour fasting and post-slaughter evaluation was carried out. The mean age of a bull on the day of slaughter was 560 days. Carcass weight, net weight gain and dressing percentage were determined.
       
The compositions of the samples of meat from the longest dorsal muscle (m. longissimus dorsi) were subjected to basic chemical analysis using standard procedures (AOAC, 2003). The pH was measured after chilling for 48 hours at pH 48, using a pX-processor PM-600 pH-meter with a combined glass electrode ESAgP-307 (in water homogenates of meat, at the meat to distilled water ratio of 1:1). Meat colour (L*, a*, b*) on the cutting area of m. longissimus dorsi was measured by a MiniScan XE Plus 45/0 apparatus (Hunter lab., USA). Cooking loss was calculated as the difference between meat sample weights before and after cooking. Marbling that appears in the rib eye area was scored from 1 (devoid) to 5 (abundant). The sensory properties of the cooked meat, namely colour, aroma, palatability, juiciness and tenderness, were estimated according to Polish Standards (Sensory analysis, PN-ISO-4121, 1998) on a five-point scale (1 point - the worst, 5 points - the best).
       
The resulting data were processed statistically using the Statistica 12.5 PL software package. The significance of differences was tested using one-way ANOVA and Duncan’s multiple range tests. Sensory analyses were evaluated with the Kruskal-Wallis test.

The LM bull calves were characterized by significantly (p<0.05) lower mean 210-day weaning weight and mean daily body weight gains from birth to weaning compared with the RA and SL bull calves (Table 1). The SL bull calves demonstrated significantly (p<0.05) higher mean body weight at 210 days compared to the RA animals, as well as significantly higher daily body weight gains. The RA bull calves had the highest unadjusted mean weaning weight, which was caused by their significantly (p<0.05) higher (by one month) mean weaning age.
 

       
The LM bulls had the highest mean daily body weight gains during fattening, whereas the SL bulls demonstrated the greater mean gains during their whole life (from birth to slaughter). These results were significantly higher than those for the RA bulls, which had the highest mean slaughter age (p<0.05) and significantly higher than that of the LM bulls (p<0.05). The mean net body weight gains for the LM and SL bulls were also significantly (p<0.05) higher than those for the RA bulls. The LM bulls were fattened for a significantly (p<0.05) shorter time and characterized by a significantly (p<0.05) lower slaughtering weight than the SL bulls. The mean carcass weight and dressing percentage of the LM and RA bulls were similar. The SL bulls were characterized by a non-significantly higher mean carcass weight and lower dressing percentage.
       
The present study showed that during the maternal nursing the best results were obtained by the SL bull calves, which were characterized by the highest mean daily body weight gains from birth to weaning and the highest mean body weight at 210 days. The LM calves had the poorest results during the rearing period.
       
It is known that breed influences growth performance (Jakubec et al., 2003; Szabó et al., 2006, Pilarczyk and Wójcik, 2007; Albertí et al., 2008; Aydin et al., 2013; Diler et al., 2016). However, few studies have compared the results of rearing and fattening, as well as meat quality, of SL and RA bull calves and the LM breed. Pilarczyk and Wójcik (2007) showed that the SL bull calves had higher mean daily body weight gains from birth to weaning and higher mean body weight at 210 days compared with the LM and RA bull calves and that the LM bull calves obtained significantly higher results than the RA animals. On the other hand, Szabó et al., (2006) reported that the RA calves were significantly heavier at 205 days than the LM calves.
       
During intensive fattening, the LM bulls had the highest daily body weight gains (over 1000 g) being fattened for the shortest period of time, which resulted in their lowest mean slaughtering age. However, their carcass weight and dressing percentage were similar to those for the RA bulls, which were significantly older at slaughter. The comparison of the net body weight gain showed that it was the same for the LM and SL bulls, which were characterized by the highest mean daily body weight gains for the whole life. This, in turn, resulted from their high body weight gains during maternal nursing and intensive fattening. The RA bulls obtained the poorest results during intensive fattening. It is well known that the Limousin breed usually has excellent growth performance and meat production under intensive feeding conditions (Chambaz et al., 2003; Cuvelier et al., 2006). In the study by Jurie et al., (2005) the LM and SA bulls were characterized by very similar mean body weight gains during intensive fattening, final weight and carcass weight.
       
The meat from the RA bulls was characterized by a significantly (p<0.05) higher content of dry matter and fat compared with the meat from the LM and SL bulls (Table 2). It was found that variations in the dry matter percentage of Longissimus muscle are associated with variations in lipid percentage (Bureš et al., 2006). Wheeler et al., (2005) found higher lipid and dry matter percentages in musculus longissimus lumborum et thoracisi in Angus- and Red Angus-sired steers than in other sire breeds, including Hereford, Simmental and Charolais.
 

       
The mean pH 48 h of meat from the bulls of the studied breeds was very similar and within the normal range, from 5.4 to 5.8 (Table 2). The pH of meat affects its colour and tenderness (Jeleníková et al., 2008; Arik and Karaca, 2017). Meat colour is an extremely important sensory characteristic by which consumers judge meat quality (Ostojić-Andrić et al., 2011). In the present study, no significant differences in the muscle colour were found among the compared breeds. Also Chambaz et al., (2003) did not observe any differences in the colour of meat between Limousin and Angus bulls, whereas Cuvelier et al., (2006) recorded a difference in L*.
       
The meat from the LM bulls was characterized by the lowest cooking loss, whereas that of the SL bulls by the highest one and this difference was significant (p<0.05). Chambaz et al., (2003) found cooking loss to be the lowest in the meat from Limousin breed, followed by Charolais and Simmental animals, with significant differences. Also in the study by Pogorzelska et al., (2013) the meat from the LM bulls was characterized by a significantly lower cooking loss than that from Charolais and Hereford breeds and in the study by Cuvelier et al., (2006) also in comparison with the Angus breed.
       
A high degree of marbling is usually associated with meat quality. In the present study, the meat from the LM bulls was characterized by a significantly (p<0.05) lower marbling compared with the meat from the RA and SL bulls. Williams et al., (2010) showed that breed effects for marbling score were most positive for the Angus breed and most negative for continental beef. Rios-Utrera et al., (2006) found effects for marbling score to be the least among Continental breeds with Limousin having the least effect.
       
The predominant intrinsic cues for consumers are tenderness, juiciness and flavour, which, after colour, have the most impact on the acceptability of beef (Beriain et al., 2009). The sensory analysis of the cooked meat showed that the best score was characteristic of the meat from the RA bulls (except for colour). However, significant differences were only found in aroma and juiciness and only in comparison with the SL breed (p<0.05). Similarly, as in the study by Vieira et al., (2007), the differences in the tenderness of the meat of the three breeds were not detected in our study; however, both studies detected breed-specific differences in the juiciness of beef. The higher juiciness values we observed in Red Angus meat were expected because of its relatively high intramuscular fat content.
       
In the study by Bureš et al., (2006), there were significant but generally small differences in sensory traits between breeds. The meat from the Angus bulls received the highest scores for odour, flavour and texture. Juiciness was scored higher in Angus compared to Charolais and Simmental. In the study by Wheeler et al., (2010), juiciness ratings were the greatest for Angus steers, intermediate for Hereford steers and least for all other sire breeds.

The best results during maternal nursing were obtained by the SL bulls and by the LM bulls during intensive fattening. Differences existed in the chemical composition and sensory characteristics of the meat depending on the breed. The longissimus dorsi muscle of the RA breed possessed a higher content of intramuscular fat and obtained higher scores for sensory characteristics; however, significant differences were only found in aroma and juiciness and only in comparison with the SL breed. The least cooking loss was recorded in the meat from the Limousin bulls.