A study in Brazil showed that by selecting nutrients and fertilisers, Nelore bulls can generate less methane and weigh more.
According to the Ibero-American Agency for the Dissemination of Science, the objective of the project developed in Brazil was to reduce the environmental impact of beef cattle production systems and improve zootechnical and economic performance. To achieve this, they analyzed the impacts of nitrogen use and feed supplementation on methane emissions and animal grazing and productivity. The results left pleasant surprises.
The researchers from Brazil, Australia and the United States who supported this study proved this The nitrogen fertilization of the pasture and the contribution of selected nutrients to the diet of the herd can lead both to the reduction of methane emissions as well as an increase in productivity and greater economic efficiency in livestock farming.
The research, which began in 2014, used various management strategies for tropical pastures, one of these, the management technique known as light interception, i.e. the percentage of sunlight trapped by the leaves, in a percentage of 95% and a height of grass suitable for fertilization.
This technique does not take into account the previously planned rotation of the livestock in the pastures, but rather the height of the pasture. Thus it allows to offer the animals a continuous supply of better quality forage, with a high percentage of grazed leaves, as well as highly digestible proteins, soluble nitrogen and low quantities of indigestible fibres. The latter, the main cause of methane emissions, produced in the digestion of ruminants and eliminated with belching and breathing.
To prove the hypothesis, two experiments were performed. In the first, analyzed the increase in occupancy rates of bullsnitrous oxide, carbon dioxide and methane, in the Nelore breed in pastures of the Brachiaria brizantha type, managed with 25 centimeters of height and fertilized with four levels of nitrogen of 0, 90, 180 and 270 kilos (kg) per hectare for 150 days in the rain season.
In the second experiment, the researchers supplemented the animals’ dietin this grazing regime, with salt and a protein supplement consisting of soy bran, urea and residues from the distillation of corn alcohol.
The preliminary results of the first experiment indicated that with the simplest forage of the best quality – without the application of nitrogenous fertilizer –, the pasture occupation rate rises to three heads per hectare per year. Meanwhile, by applying 180 kg of nitrogen during the rainy season, the occupancy rate reaches six animals per hectare.
By analyzing methane emissions, they concluded that with the use of nitrogen fertilization, lower methane emissions were recordedcompared to those recorded by the livestock sector without the use of fertilization.
Even animals have experimented a daily weight gain, since they came to weigh between 980 grams and 1.1 kg more, with the nitrogen fertilization of the pastures. “In the current system of rearing cattle cut to pasture, without nitrogen fertilization, the weight gain of the animals fluctuates between 500 and 700 grams”, compares one of the researchers.
The results of the second experiment, on the other hand, indicated that the addition of a protein/energy supplement to the animals’ diet determined an increase of 100 to 150 grams per day in the weight of the bovine, compared to that obtained through the use of mineral salts. “This results in a shorter fattening time, with the earlier release of grazing areas, and therefore also methane emissions are reduced for a longer time in the life of the animals,” says Andrade Reis, one of the researchers. .
