Introduction

The constant increase in world demand for meat in recent decades has challenged production systems to increase their economic indicators, maintaining the sustainability of their means of production and the quality of the final product. Among the demands of this expanding market, product quality becomes even more important, showing that it is also a niche market for adding value and improving economic results throughout the production chain.

According to the 2016 Agricultural Census, the Brazilian cattle herd has 172.7 million animals, 35.4% of which are in the Midwest region of the country. With a smaller herd, the South of the country has approximately 23.5 million head, with 48.6% of this herd in Rio Grande do Sul (RS)⁽¹⁾.

Although less significant in terms of quantity, RS plays an important role in the supply of quality meat. In 2017, there were around 7.8 million cattle raised for beef in the state⁽²⁾, predominantly breeds of European origin, which are preferred in gourmet markets. Research shows that 64.8% of the Gaucho herd comprises animals defined as from a European breed or crossbred. Among the breeds used, Aberdeen Angus and Hereford predominate, making up the largest portion (30%) of the crosses between European breeds⁽³⁾.

Recognised for producing quality meat, in recent years the main destinations for meat from RS have been Santa Catarina (14,392 tons) and São Paulo (9,196 tons). In these markets, particularly in the capital, restaurants and specialised meat shops look for products originating in breeds and crosses with European animals, and in meat programmes of the principal British breeds⁽²⁾, especially Hereford and Aberdeen Angus, brands that are also found in other countries.

Being the oldest breed with links to branded meat on the Brazilian market, Hereford cattle are currently of great importance in crossbreeding, especially in production systems that aim at the precocious slaughter of males and the mating of heifers when they are close to fourteen months of age⁽⁴⁾. According to a report from the Ministry of Agriculture, Livestock and Supply, in 2018 in Brazil, 152,936 cattle of both sexes were registered in the Hereford herd, with 145,644 animals in RS, the equivalent to 95% of the Brazilian herd of Hereford cattle⁽⁵⁾.

Precocity is inversely correlated with one of the characteristics most appreciated by consumers, the tenderness of the meat. This fact influences the slaughterhouse industry and cattle breed associations to encourage producers to terminate animals when young, with awards and bonuses to breeders who produce precocious animals⁽⁶⁾. Precocious slaughter, therefore, coupled with other productive factors and the increase in consumer demand for quality food, results in industries investing in certification and traceability programmes⁽⁷⁾. This ensures the producer more adequate remuneration for carcase quality, also guaranteeing transparency and credibility between the various links of the beef production chain(8). As such, the aim of this study was to understand and analyse precocity behaviour over nine years in Hereford steers and their crosses, slaughtered with from zero to six teeth.

Material and methods

The work was carried out at the Federal University of Santa Maria, and used as an analysis tool slaughter data from 2010 to 2018 of a slaughterhouse under the Federal Inspection Service (SIF), located in the Central Region of Rio Grande do Sul.

Information was collected on 1.22 million cattle slaughtered over the nine years with from zero to six teeth, from different districts in the state of Rio Grande do Sul. Both sexes were represented, but only female or castrated male cattle were considered. Uncastrated males, or those showing the characteristics of late castration, are disqualified from the Carne Pampa programme, and were not included in the analysis.

After filtering the data, approximately 144 thousand castrated males and 52 thousand females, certified in the Carne Pampa programme, were obtained, totalling approximately 197 thousand evaluated carcases. For this study, only the data of the 144 thousand males were evaluated. The racial pattern of the animals was classified by technicians in the pre-slaughter pens, where the phenotypic characteristics required to include the animals in the program were visually identified: such as the coat, characterised as red with the face, belly, end of the tail and lower parts of the limbs completely white, as described by Severo et al.⁽⁹⁾

After slaughter, the degree of finish of the carcases was checked by verifying the distribution and amount of fat cover at different places on the carcase (thoracic, lumbar region and over the thigh), where: lean (1) = no fat; little fat (2) = 1 to 3 mm of subcutaneous fat; medium fat (3) = between 3 and 6 mm of subcutaneous fat; uniform fat (4) = over 6 and up to 10 mm thick; and excessive fat (5) = over 10 mm thick.

Carcases of animals with a racial pattern, whether from a female or castrated male animal, with a finish equal to or greater than 3.0 mm, and with up to six teeth, were certified as carcases included in the Carne Pampa programme.

Seeing the variations in animal category on offer throughout the year due to forage availability and the handling of the various bovine categories, the researchers understood the need to divide the year into three periods. The periods were grouped into three seasons with dates defined according to a report by the Frigorífico Silva slaughterhouse, prepared in 2016, in which information was collected regarding the nutritional basis at termination of the animals slaughtered that year. The data showed that during the year under study, in approximately 5 thousand lots, the 143 thousand slaughtered animals came from different production systems, in this case, natural pasture, summer or winter cultivated pasture, and confinement.

According to the report, between 26 December and 25 May, the animals were predominantly finished on summer, natural or cultivated pasture. This period was therefore classified as the hot season. From 26 May to 25 July the animals came predominantly from confinement, with a small percentage from winter pasture at the start of the cycle, but these latter were animals that already had some deposition of fat accumulated during the hot season. This period was classified as the autumn void. From 26 July to 25 December, the animals came from finishing systems on cultivated winter pasture, with few animals from confinement lots, this period being classified as the cold season.

To assess the behaviour of the cold carcase weight of the steers over the nine years by season and by dentition, the data were submitted to simple linear regression analysis, with the cold carcase weight as dependent variable, and the year and dentition as regressor variables.

The mathematical model used was:

ŷ = b0 + b1xi

In the linear regression analysis, the years 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 and 2018 were replaced by the numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 respectively.

The analysis was carried out using the SAS University Edition statistical software.

Results and discussion

Figure 1 shows a variation in the percentage representation of steer dentitions over the years. The percentage of animals slaughtered with four teeth gradually decreased from 2011 to 2016 and then increased from 2017 to 2018.

From 2014 to 2018, the percentage of animals slaughtered with zero teeth was higher than that of animals with six teeth, which implies an increase in early slaughter over the last four years; in addition, from 2010 to 2018, the percentage of animals slaughtered with two teeth was greater than that of animals slaughtered with four and six teeth, indicating the slaughter of younger animals.

Although Figure 2, shows some fluctuation during the period under analysis, the increase in cold carcase weight from 2010 to 2018 is evident for all categories.

The mean cold carcase weight of animals slaughtered with zero and two teeth showed a gradual increase from 2010 to 2012, a period when the weight difference in these categories was 28 kg and 16 kg respectively.

Table 1 shows the mean value and increase in cold carcase weight of the steers, separated for production period. Steers finished during the autumn void show an annual increase of 4.76 kg in cold carcase weight (P<0.01). During both the cold and hot seasons this increase is greater than 6.0 kg, with values of 6.45 and 6.38 kg respectively. These results show an improvement in the precocity of the slaughtered animals, a fact not reported in the domestic literature where there are few studies on precocity, most of the research being related to reproduction^{(10, 11, 12)}.

Figure 3 shows that the highest number of animals with zero teeth were slaughtered during the autumn void season, with the lowest percentage during the hot season, indicating a greater use of this category in more-intensive feeding systems, such as confinement, which is used mainly during the off-season between the hot and cold-season pastures. Terminating cattle during the hot season is the result of termination systems using native pasture, with or without the use of supplements.

Furthermore, Figure 3 makes it clear that, just as in the hot season, during the winter, the highest percentage of slaughtered animals had four teeth. This may indicate that cold-season pasture continued to be used in cattle that did not reach the desired finish in native summer pastures.

Regardless of the period under study, animals slaughtered with six teeth had the smallest percentage participation in the different seasons, demonstrating an attempt by producers to determine the precocity of the animals. This can be explained by the use of pastures grown during the hot and cold seasons, aiming at the termination of younger animals that might be included in quality meat programmes. Some authors report that in addition to the importance of slaughter age, cattle finished immediately after weaning are more efficient during termination compared to those not fully grown after weaning⁽⁵⁾.

Despite an increase in costs, producers select and finish animals that show the racial pattern, weight and age required by the regulations of the certification programme. This happens due to the carcase bonus offered by the industry for carcase certification(5,8). Due to the speedy acceptance by consumers of certified meat in recent years, slaughterhouses have increased the bonuses to guarantee supply of the product⁽¹³⁾.

The important increase in the use of animals with zero and two teeth, may indicate a probable advance in the use of feeding technology which accelerates and intensifies the production process and reduces the slaughter age of the animals. Animals with six teeth are also influenced by the use of this technology, but at the time of writing, the slaughterhouses in this research no longer offered a bonus for animals with this dentition, providing certification for up to four teeth only.

According to Vaz et al.⁽¹⁴⁾, the evolution of the slaughter of young cattle is a result of the use of more-intensive production systems, with a growth in birth rate and weaning rate greater than 80%, contributing to increase the number of calves produced.

Based on the data in Table 2, it can be seen that younger animals slaughtered during the cold season showed a greater annual weight increase; steers slaughtered with zero, two and four teeth, showed an increase greater than 2.0 kg in cold carcase weight per year, while steers slaughtered with six teeth showed a lower weight increase during the cold season, of only 1.2 kg/year.

The greater increase in cold carcase weight per year seen during the cold season is due to animals from finishing systems that use pasture grown in winter. As such, Azevedo Junior⁽¹⁵⁾ concluded that the use of winter pasture, together with supplementation, is an alternative that helps to increase the rate of growth of the animals and reduces the age of slaughter.

When observing the number of animals slaughtered per year for each dentition, it should be noted that during the cold season, the slaughter of younger animals, such as steers with two teeth, predominates and represents 36.5% of the total slaughtered over the nine years. Animals with six teeth made up 12.2% of the total number of slaughtered Hereford animals.

Table 3 shows that steers finished with zero teeth during the hot season presented an annual increase in cold carcase weight of 1.87 kg (P<0.01), and animals slaughtered with two teeth had an increase of 2.12 kg (P<0.01). The annual increase in cold carcase weight of animals slaughtered with four and six teeth was lower, 1.79 kg and 0.60 kg respectively. There is an increase in slaughter precocity due to the greater increase in cold carcase weight found in the categories of animals slaughtered with zero and two teeth.

Therefore, with the increase in precocity, the offer of quality meat in the slaughterhouse industry is greater, since Kuss et al.(16), researching the slaughter of castrated and non-castrated males slaughtered at 16 and 26 months, found that in the super-young category (16 months) the characteristics of tenderness, juiciness and palatability were similar between the castrated and non-castrated animals, whereas in the young category (26 months), the meat of the non-castrated animals was less tender compared to that of the castrated animals. These results show that reducing the age of slaughter affords higher quality meat.

Table 4 shows that during the autumn void season, over the nine years there are more steers slaughtered with zero teeth, and the lowest number of animals slaughtered with six teeth, with an average of 223 head per year. The zero-tooth classification reached an average of 562 animals per year.

In relation to weight increase over the nine years, animals with six teeth had the lowest annual increase, with 0.94 kg, while the category of animals with two teeth showed the greatest weight increase during the autumn void, where carcase weight went up by 2.63 kg per year. Steers with two teeth show better performance during confinement compared to younger animals⁽¹⁷⁾, which explains the increase, as this is the most-employed category in the intensive finishing systems characteristic of this season, with the result that producers seek to improve these nutritional systems, each year prioritising an improvement in efficiency and, consequently, carcase weight.

In general, there has been an improvement in genetic quality or breeding and fattening technology, which has increased the cold carcase weight of Hereford animals and their crosses, regardless of the finishing system used during the fattening phase, characterised in this study by the seasons. In addition, new studies that investigate the evolution of slaughter precocity in animals from different breeds are important to identify the direction of livestock farming in different regions of the country, and improvements in the rearing and finishing technology of animals destined for quality meat programmes. Market data show that in other countries, adding value to certified meat cuts often means the viability of beef production chains.

Conclusions

From 2010 to 2018, there was an evolution in slaughter precocity and an increase in the cold carcase weight of Hereford steers.

The greatest increase in cold carcase weight occurred during the cold season. In this season, zero-tooth steers showed the greatest increase.

Steers with two teeth showed a greater increase in cold carcase weight during the hot and autumn void seasons each year.

Acknowledgements

The authors would like to thank Frigorífico Silva Indústria e Comércio Ltda. and the Associação Brasileira de Hereford e Braford for providing the data.

F.N.V. is a member of Rede Marcane, founded by CYTED (ref. 116RT0503).

References