eduardo cesarBullocks gained weight more rapidly with controlled food and pasturingeduardo cesar
Brazil has the largest commercial herd of cattle on the planet, with some 167 million head, and is the leading country in beef exports. They are positions of leadership that do not exactly show excellence in this sector. In spite of the success, the productivity of the Brazilian herd still falls short of what is desirable While in the United States and European countries, beef cattle is already ready for slaughter less than 2 years old, in Brazil, the animals are slaughtered, on average, at the age of 3.5 years, to reach the weight required by the abattoirs [from 240 kilos (kg) to 330 kg].
It is distortions like this that led two dozen researchers from four research institutions to dive headfirst into a project funded by FAPESP and by the Brazilian Agricultural Research Corporation (Embrapa). After five years, they reached some good results, amongst them the slaughter of animals with a carcass weight of 244 kg (the skeleton and the meat) in one year and four months, and they also managed to reduce the time from the first birth of the heifers, of up to 4 years, to an average of 29 months. They are economic gains for cattle raising that have not yet been totally quantified. The researchers are at the stage of collecting and analyzing the data.
Another contribution is the Maximum Profit Feed, created by using a mathematical model developed by the researchers. With it, the producer describes the animal and enters the details of its food. From then on, the program gives advice on the ideal diet for the production of cattle with the characteristics desired. About 300 cattle raisers, livestock companies and animal feed factories are now using the program.
Complete cycle
“We did a broad project for animal production, which involves genetic improvement, reproduction, nutrition, health, pasturing, and molecular genetics”, explains the coordinator of the project, agronomist engineer Maurício Mello de Alencar, a researcher with Southeast Embrapa Cattle, located at Fazenda Canchim, in the municipality of São Carlos, in São Paulo. “Several Brazilian researchers had already dealt with this question, but usually in works that focused isolated phases of the production system. The novelty of this project is that it tries to assess the complete life cycle of the cattle, from the moment of birth to when it is ready for slaughter”.
The researchers assessed animals from different genetic groups, born from cows of the Nelore race cross-bred with bulls from the same race and from others like Canchim, Angus, and Simmental. The Nelore is a zebu (Bos taurus indicus) of Asian origin and it predominates in Brazilian cattle breeding. It is estimated that over 80% of the Brazilian herd is made up of animals from this race and those of mixed blood derived from it. The Canchim, in turn, is a breed created in Brazil from the zebu races Nelore, Indo-Brazilian, and Guzerat, with bulls from the Charolais race, of European origin (Bos taurus taurus). It was created at the beginning of the 1950’s and has the characteristic of the bullocks? precociousness in weight gain. The Angus and the Simmental are also animals of European origin.
“We tried to use races that represent distinct biological types, to produce different animals, and from there, to be able to study in depth their characteristics”, Alencar explains. In all, 600 Nelore cows were used in the experiment. With the crossbreeding, carried out by artificial insemination or natural mounting, they sought to unite the best characteristics of the zebu races, known for their rusticity and for adapting easily to Brazilian conditions of climate and pasture, and of the European ones, which, under favorable environmental conditions – mild climate, low infestation by parasites, and good nutrition – are more productive.
The researchers also decided to experiment with differentiated ways of breeding and feeding (handling). Instead of adopting the extensive production system, with a small number of animals on the pasture (an average of one cow or adult male per hectare), they opted for the intensive regime, with a distribution of five head per hectare. In extensive cattle raising, the kind most used in Brazil, the animals stay on the pasture, feeding on forage plants, in particular the so-called brachiarias. This is a system that does not involve proper handling, fertilization, or correction of the soil. “About 40% to 50% of these pastures show some level of degradation”, says agronomist Luciano de Almeida Corrêa, from Embrapa’s team of researchers.
To support a higher number of animals on the pasture, the researchers needed to carry out fertilization and soil correction, and they used some other forage species to feed the cattle, such as Tanzania grass and palisade grass. “These forage grasses showed good results in animal performance and in the quantity of animals per area. Depending on the fertility of the soil and the level of fertilization, we managed to put up to ten animals per hectare during the period of the rains”, says Corrêa. In the dry period, as the production of forage is about 10% to 20% of the total annual production, the pasture is supplemented with grass silage.
To get the best out of the forage produced, the researchers also used a system of pasture rotation. The pasture is divided into smaller areas called pickets, and there is a periodical change of animals between these demarcated areas. This system proved to be the most suitable because, particularly under intensive fertilization, it guarantees greater uniformity and greater efficiency of pasture than the continuous system. Furthermore, pasture rotation prevented the soil from being compacted with the intense trampling of the animals. “Compacting is eliminated by fertilization and by resting the pasture for about 30 days”, says Odo Primavesi, a specialist in soils and in plant nutrition from Southeast Embrapa Cattle.
To check whether this differentiated handling was resulting in an animal with better production characteristics, the researchers assessed the rate of growth and body composition of the four genetic groups (Nelore, and the Canchim-Nelore, Angus-Nelore, and Simmental-Nelore crossbreeds). To do so, studies were carried out of food conversion, which is the ratio between the quantity of food consumed by the animal per kilo of weight gain. The composition of this growth was determined over the animal’s life. This analysis is important, because the composition of the weight – how much the animal gains in muscle or fat – defines the nutritional requirements of the herd.
“With this information, we give guidance to the breeders and feed manufacturers about the composition of the food that the herd needs to be given”, explains the agronomist engineer, specialized in nutritional biochemistry, Dante Pazzanese, from the Luiz de Queiroz College of Agriculture (The Luiz de Queiroz College of Agriculture (Esalq/USP), of the University of São Paulo (USP). To arrive at the results, over 300 animals were slaughtered. All their tissues (fat, muscles, etc.) were analyzed. As the animals were studied at different ages, it was possible to draw the growth curves for each body tissue and their proportion in the animal at each age or weight.
“We have established a rich set of data for determining which genetic group is better for depositing fat or muscle and, at the same time, we have generated precious information about the nutritional diet for each genetic group”, explains Pazzanese. The animals resulting from crossbreeding with the Angus race showed the highest rates of gain and the most precociousness in laying down fat. Another interesting aspect is that the animals crossed with the Angus deposited intramuscular fat (marbling) earlier, and it is this marbled meat that commands the best prices in the international market.
The experiment also proved to be useful for meat exporters, in that they can produce an animal with the characteristics of body composition required by each country – the Japanese like an extremely fatty meat, while the Americans prefer a meat regarded, by our standards, as fat, and the Europeans, a leaner meat. “With our studies, we define the weight at slaughter for each crossbreed, assessed in accordance with the market for which it is intended. This means that the meat exporters can draw up strategies for attending to the different purchasing companies”, Pazzanese says.
Reproductive efficiency
One of the subprojects of the research refers to the reproductive efficiency of the cows. In Brazil, procreation starts later than with the animals bred in countries where cattle breeding is more developed. The researchers’ objective, then, was to make heifers come to puberty, the age of the first birth, earlier, and to reduce the interval between the first and the second set of offspring. “In beef cattle, the efficiency of the production is tied up with reproductive efficiency”, explains agronomist Armando de Andrade Rodrigues, responsible for this subproject. According to the researcher from Embrapa, the Nelore cows in Brazil first give birth, on average, at the age of 4 years, which is regarded as very late.
“In the United States and in Europe, cows give birth to their first offspring when they are about 2 year sold”, he says.”The two main variables that determine when the heifer reaches puberty are age and weight. Food, then, has a very important role in bringing down the start of the reproductive age”, the researcher says. “We found that the females born of the crossbreeding of Nelore cows with bulls from other races are more precocious than the pure Nelores. While the latter first came on heat, on average, at 16.5 months, the Nelore and Canchim crossbreeds reached the reproductive age at 14.5 months, the offspring of Simmental and Nelore at 13.4 months, and those from Angus and Nelore, at 12.3 months”, Rodrigues says. All the animals were given the same diet. In the rainy period, they were kept in pasture rotation and fertilization systems, with forage called coastcross grass (Cynodon dactylon), and in the dry season the animals were supplemented with sugarcane and urea.
Another aspect assessed by the researchers was the age of the first birth. In this item, it was observed that the cows born from crossbreeding Angus with Nelore and Nelore with Simmental were the most precocious. They gave birth, on average, when 29 months old. The Canchim-Nelore animals had their first birth with 32 months, and the pure Nelores with almost 37 months. The eight months of difference between the birth of the first litter of the crossbred animals and the pure Nelores represents a considerable gain in reproductive efficiency and, at the same time, a substantial reduction in the breeder?s spending on the herd.
A study similar to that carried out with the females was done with the males. What was looked for, in this case, were alternatives for producing, earlier on, quality meat from young bullocks. “In order to reduce the age for slaughter in Brazil, it is fundamental to improve the animals’ nutrition, whether by means of the quality of the pasture, or by the food supplied in the trough in the dry months”, explains researcher Geraldo Maria da Cruz, from Embrapa, a specialist in animal nutrition. The average standard for the slaughter of cattle in the country is 3.5 years (about 42 months) and 17 arrobas (255 kg) – the meat packing stations require from 16 to 22 arrobas (from 240 to 330 kg).
“There was a very large improvement in our project, in relation to the national average”, says Cruz. Pure Nelore cattle reached 16.3 arrobas (244.5 kg) at 16 months, and Canchim-Nelores reached 19.3 arrobas (289 kg) with 16 months. And the Angus-Nelores were weighing 20 arrobas (300 kg) at 15 months, and the Simmental-Nelores , 21 arrobas (315 kg) at 16 months.The researchers also assessed two alternatives for handling: confining the calves and feeding them in the trough, or providing a small supplement in pasture. In the case of the animals that went straight into confinement, the average of the four genetic groups was 15.6 arrobas (234 kg) at 13 months. Amongst those kept in the pasture, 16.7 arrobas (250.5) at 20 months. “In all the situations, the improvement in the age at slaughter is evident.”
Molecular genetics
The project also included genetic research with the animals from the four groups. “We did studies of the DNA of the animals used as reproducers, to try to identify which ones would generate heterotic offspring, or more heterotic for the desired characteristics”, claimed veterinary doctor Luciana Correia de Almeida Regitano, from Embrapa. Heterotic offspring are those that have weight at slaughter, daily weight gain, beginning of reproductive age, or weight at weaning higher than the average of their parents. In this study, ten molecular markers of some 730 animals were analyzed. “We worked with a limited number of animals and molecular markers, but we obtained good indications that there is a direct relation between the genetic distance of the parents and the heterosis of the calves”, the researcher explains. Accordingly, the more different are the genetic profiles of the cow and of the bull (such as racial differences and differences in lineages), the greater is the probability of the calves having a better performance than their parents.
Besides all these results, the project was important for disseminating technology and for qualifying human resources. During the four years of activity, over a hundred students for secondary and university courses, connected with the areas of biology and agrarian sciences, carried out attachments in the various experiments carried out in the research. Field days were also held, and talks given to the producers. The project was also able to count on researchers from the São Paulo State University (Unesp) at Jaboticabal and from the State of São Paulo Zootechny Institute of Nova Odessa and Sertãozinho, from the Faculty of Zootechny and Food Engineering of the University of São Paulo in Pirassununga, and the collaboration of the municipal government of São Carlos.
The Project
Crossbreeding Strategies, Handling Practices and Biotechniques for the Sustained Intensification of Beef Production (nº 98/03761-0); Modality
Thematic Project; Coordinator Maurício Mello de Alencar – Southeast Embrapa Cattle; Investment R$ 433,333.20 (FAPESP)
