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The goal of this bibliographical study was to provide information about residual feed intake (RFI), a new criterion used in the selection of beef cattle for growth rate, food ingestion, and feed efficiency. RFI is calculated as the difference between real consumption and the quantity of food an animal is expected to eat based on its mean live weight and rate of weight gain. In studies of RFI, many speculations are made among researchers about the reliability of this criterion. However, there is a high genetic correlation with characteristics related to post-weaning consumption and maturity, indicating that the biological processes that regulate consumption and efficiency in young animals are similar to the processes that regulate consumption and efficiency in animals of greater age. In contrast to feed conversion, selection based on RFI seems to select for lower rates of consumption and lower animal maintenance requirements without changing adult weight or weight gain. Therefore, we conclude that the data indicate that there are extraordinary benefits to be gained from changing the goals of selection from increased weight gain to improved nutritional efficiency. Given the importance of animal production for economic development in Brazil choosing the best selection goals for livestock improvement is essential. To include an index of feed efficiency in future goals would be desirable, and RFI may play a part in this if economic methods of implementation can be developed.

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Recent studies carried out in Brazil have shown that strains from the same Toxoplasma gondii genotype can infect humans, domestic animals (dogs and cats) and animals slaughtered for human consumption (pigs, sheep, goats, and chickens), suggesting a common infection route. However, little is known about the importance of free-living wild birds within this epidemiological context. The objective of this work was to isolate, genotype, and evaluate the virulence for mice of new isolates of T. gondii obtained from free-living wild birds from the state of Minas Gerais, Southeastern Brazil. From August 2016 to June 2017, T. gondii was isolated from the hearts and brains collected from 6 out of 45 free-living wild birds, namely, a roadside hawk (Rupornis magnirostris), a campo flicker (Colaptes campestris), a southern caracara (Caracara plancus) and a tropical screech-owl (Megascops choliba), all rescued in Belo Horizonte. One isolate was obtained from a toco toucan (Ramphastos toco), rescued in Cristiano Otoni, and another was obtained from southern caracara, rescued in Santa Luzia. Five different genotypes were identified by PCR-RFLP. A unique genotype was shared in two different isolates obtained from a southern caracara and a toco toucan. This genotype has never been previously described in any other host or place. Three isolates were classified as of intermediary virulence and three isolates as avirulent for mice. The combined analysis of alleles ROP18/ROP5 (a serine/threonine kinase, and a polymorphic pseudokinase, respectively) was effective in determining the virulence of five of all the isolates with the exception of that from R. magnirostris. Atypical isolates of T. gondii obtained from free-living wild birds rescued in the state of Minas Gerais share the same genotypes of strains that infect humans, domestic animals, and animals slaughtered for human consumption.

This study aimed to identify members of the Sarcocystidae family in naturally infected wild birds at a rescue center in the state of Minas Gerais, southeastern Brazil. The heart and brain of 44 wild birds were evaluated by bioassay in mice to detect T. gondii, and extracted DNA was used for nested PCR of the 18S ribosomal DNA gene to detect members of the Sarcocystidae family. The positive samples were sequenced, assembled, edited and compared with sequences deposited in GenBank. Toxoplasma gondii was isolated from six (13.6%) out of 44 birds. Toxoplasma gondii DNA was identified in 10/44 (22.7%) of the birds. The amplified sequences exhibited 100% similarity with the DNA of the ME49 strain of T. gondii. Sarcocystis DNA (99% similarity) was identified in 5/44 (11.4%) of the birds. T. gondii and Sarcocystis spp. are common in wild birds in Minas Gerais, Brazil.