A breeding program for Nile tilapia in Brazil: Results from nine generations of selection to increase the growth rate in cages.

Variance components and heritabilities for daily weight gain (DWG) were estimated for Nile tilapia farmed in cages across nine generations (G1-G9) of selection in a breeding program in Brazil. DWG was measured in 16,272 accumulated tagged animals representing 535 full- and half-sib families of Nile tilapia under cage farming. The additive genetic variance showed a slight variation (0.051-0.066), and heritability estimates ranged from 0.20 to 0.33. The common environmental effect accounted for a higher proportion of the total variance in DWG, especially in the last generations (6%-24%). A genetic trend based on all data available showed a substantial increase in the DWG (about 3.3% per generation) of Nile tilapia across nine generations of selection. Furthermore, our results demonstrate ample scope for further genetic improvement.

DHA from microalgae Schizochytrium spp. (Thraustochytriaceae) modifies the inflammatory response and gonadal lipid profile in domestic cats.

The present study aimed to evaluate the inflammatory response, oxidative status and fatty acid deposition in reproductive tissues of cats supplemented with the dried microalgae Schizochytrium spp. (Thraustochytriaceae) as a DHA source. Thirty-seven cats (males, n 21; females, n 16; 11·5 (sd 0·5) months of age) were divided by sex into five groups. Treatment diets contained algae biomass at 4·0, 8·0, 12·0 or 16·0 g/kg replacing poultry fat (n-6 source). Cats were fed the respective diet for 62 d and neutered on day 58. Blood samples were collected at the beginning of the experiment (day 1), before neutering (day 58) and 4 d after surgery (day 62) for analysis of inflammation and oxidative markers. Acute-phase protein levels were altered (P < 0·01) in the postoperative period, without any treatment effect (P > 0·05). PGE2 concentrations after surgery were reduced linearly (R2 0·8706; P = 0·002) with microalgal inclusion. Blood platelet count was reduced (P = 0·001) after the surgery regardless treatment, but it was higher in the DHA group compared with control (P < 0·001). The DHA deposition (testicles, R2 0·846; ovaries, R2 0·869) and the n-6:n-3 ratio (testicles, R2 0·859; ovaries, R2 0·955) in gonads had a pattern which fitted a quadratic model. DHA from Schizochytrium spp. modifies PGE2 response after the surgery in cats. The physiological roles of the DHA in the reproduction of cats were not investigated, but its gonadal deposition after supplementation was observed.

Effects of genotype × environment interaction on the estimation of genetic parameters and gains in Nile tilapia.

Nile tilapia (Oreochromis niloticus) is the major fish species produced in Brazil, a country with a vast territory and great climate diversity. This study assessed the effects of the genotype × environment interaction on heritability estimates and selection responses in Nile tilapia (Tilamax strain) cultivated in earthen ponds and net cages. The weight at harvest, trunk length, and head percentage of 4400 individuals were determined. Trait heritabilities were higher in pond fish (0.27-0.52) than in caged fish (0.09-0.33). Genetic correlations between farming systems were lower than 0.5 for the three traits. The rank position of the top 10 families differed according to the environment, as did the response to direct and indirect selection. The results revealed significant genotype × environment effects on the heritability of Nile tilapia farmed under different systems.

Heritability of hip dysplasia: Preliminary results for German Shepherd dogs in Brazil.

The heritability of canine hip dysplasia in German Shepherd dogs was estimated using Bayesian methods. Data on hip score and status of 1632 dogs born from 1990 to 2013 were provided by the Brazilian Society of German Shepherd Breeders. Heritability estimates (mean ± standard deviation) were 0.1979 ± 0.058 for hip scores and 0.187 ± 0.055 for hip status. We observed no phenotypic trends and a small rate of genetic trend (0.52%) according to the year of birth, probably because of ineffective phenotypic selection and absence of genetic selection. The heritability estimates in this study can be used to achieve effective selective breeding and genetic gains, which in turn can result in improvements in dog health and welfare.

Genetic parameters for growth performance, fillet traits, and fat percentage of male Nile tilapia (Oreochromis niloticus).

Improvement of fillet traits and flesh quality attributes are of great interest in farmed tilapia and other aquaculture species. The main objective of this study was to estimate genetic parameters for fillet traits (fillet weight and fillet yield) and the fat content of fillets from 1136 males combined with 2585 data records on growth traits (body weight at 290 days, weight at slaughter, and daily weight gain) of 1485 males and 1100 females from a third generation of the Aquaamerica tilapia strain. Different models were tested for each trait, and the best models were used to estimate genetic parameters for the fat content, fillet, and growth traits. Genetic and phenotypic correlations were estimated using two-trait animal models. The heritability estimates were moderate for the fat content of fillets and fillet yield (0.2-0.32) and slightly higher for body weight at slaughter (0.41). The genetic correlation between fillet yield and fat was significant (0.6), but the genetic correlations were not significant between body weight and fillet yield, body weight and fat content, daily weight gain and fillet yield, and daily weight gain and fat content (- 0.032, - 0.1, - 0.09, and - 0.4, respectively). Based on the genetic correlation estimates, it is unlikely that changes in fillet yield and fat content will occur when using growth performance as a selection criterion, but indirect changes may be expected in fat content if selecting for higher fillet yield.

Correlated changes in body shape after five generations of selection to improve growth rate in a breeding program for Nile tilapia Oreochromis niloticus in Brazil.

Body shape is a commercial trait of great interest as it impacts profit and productivity of aquaculture enterprises. In the present study, we examined correlated changes in two measures of body shape (depth to length ratio, DL-R and ellipticity of mid sagittal plane, EL-H) from a selection program for high daily weight gain in a Nile tilapia population reared in freshwater cages in Brazil. Genetic parameters for body shape and its genetic association with growth traits (body weight and daily gain) were also estimated from 8,725 individuals with growth performance recorded over five generations from 2008 to 2013. Mixed model analysis showed that the selection program resulted in substantial improvement in growth performance (about 4 % genetic gain per generation or per year) and also brought about trivial changes in body shape. The heritabilities ranged from 0.470 to 0.564 for growth traits and 0.180 to 0.289 for body shape. The common family effects were low for all traits studied, accounting for only 3-11 % of total phenotypic variance. The genetic correlations between body shape and growth traits were weak, i.e., -0.385 between EL-H and growth traits and 0.28 between DL-R and body weight or daily gain. Strong and negative genetic association was found between the two body shape traits (rg = --0.955). Harvest body weight and daily gain are essentially the same traits, as indicated by the close to one genetic correlations between the two characters. Our results demonstrated that the selection process to increase growth rate had small, but slowly constant effect in body shape traits; and in the long term, the fish would have become rotund.

Performance of Africanized honeybee colonies settled by queens selected for different traits / Desenvolvimento de colônias de Apis mellifera formadas com rainhas selecionadas para diferentes características

We evaluated varroa infestation and the performance of Africanized honeybee colonies with queens selected for honey and royal jelly production, and also unselected queens, correlating with climatic variables. In Campo Alegre, Santa Catarina State, Brazil, the experiment I used 10 Langstroth hives and in Mafra, Santa Catarina State, Brazil, the experiment II was performed with 15 Schenk hives. A mapping in areas of sealed and unsealed brood, honey and pollen was carried out on days zero, 45 and 90 days after the introduction of the queen. In the experiment I, there was interaction between the type of queen selection and the evaluation period for areas of sealed brood, honey, and total stored food. The group selected for royal jelly production presented larger sealed brood area and smaller honey area at 90 days. Varroa infestation was lower (p 0.05) at 90 days. The type of queen selection and the evaluation period influenced the sealed brood area, the total brood and the total area occupied in the colony. The high relative humidity caused greater honey storage for the local group. The different groups of queens presented different behavior according to the environment in which they are settled.

Avaliaram-se a infestação por Varroa destructor e o desenvolvimento de colônias de A. mellifera com rainhas selecionadas para produção de mel, geleia real e rainhas não selecionadas, correlacionando-se com as variáveis climáticas. No experimento I, em Campo Alegre, Estado de Santa Catariana, utilizaram-se dez colmeias Langstroth e, no experimento II, em Mafra, Estado de Santa Catariana, utilizaram-se 15 colmeias Schenk. Procedeu-se ao mapeamento das áreas de cria aberta, operculada, mel e pólen, na data de introdução, aos 45 e 90 dias após a introdução das rainhas. No experimento I, houve interação entre o tipo de seleção da rainha e a época de avaliação para as áreas de cria operculada, mel e total de alimento. O grupo selecionado para geleia real apresentou maior área de cria operculada e menor área de mel aos 90 dias. A infestação por varroa foi menor (p < 0,05) aos 90 dias. No experimento II, não foi encontrado interação para as características avaliadas. As áreas de cria operculada, total de cria e total ocupada da colônia apresentaram efeito do tipo de seleção da rainha e época de avaliação. A alta umidade relativa do ar influenciou o maior armazenamento de mel para o grupo local. Os diferentes grupos de rainhas responderam diferentemente em função do ambiente onde estão inseridas.

Performance of Africanized honeybee colonies settled by queens selected for different traits / Desenvolvimento de colônias de Apis mellifera formadas com rainhas selecionadas para diferentes características

We evaluated varroa infestation and the performance of Africanized honeybee colonies with queens selected for honey and royal jelly production, and also unselected queens, correlating with climatic variables. In Campo Alegre, Santa Catarina State, Brazil, the experiment I used 10 Langstroth hives and in Mafra, Santa Catarina State, Brazil, the experiment II was performed with 15 Schenk hives. A mapping in areas of sealed and unsealed brood, honey and pollen was carried out on days zero, 45 and 90 days after the introduction of the queen. In the experiment I, there was interaction between the type of queen selection and the evaluation period for areas of sealed brood, honey, and total stored food. The group selected for royal jelly production presented larger sealed brood area and smaller honey area at 90 days. Varroa infestation was lower (p 0.05) at 90 days. The type of queen selection and the evaluation period influenced the sealed brood area, the total brood and the total area occupied in the colony. The high relative humidity caused greater honey storage for the local group. The different groups of queens presented different behavior according to the environment in which they are settled.(AU)

Avaliaram-se a infestação por Varroa destructor e o desenvolvimento de colônias de A. mellifera com rainhas selecionadas para produção de mel, geleia real e rainhas não selecionadas, correlacionando-se com as variáveis climáticas. No experimento I, em Campo Alegre, Estado de Santa Catariana, utilizaram-se dez colmeias Langstroth e, no experimento II, em Mafra, Estado de Santa Catariana, utilizaram-se 15 colmeias Schenk. Procedeu-se ao mapeamento das áreas de cria aberta, operculada, mel e pólen, na data de introdução, aos 45 e 90 dias após a introdução das rainhas. No experimento I, houve interação entre o tipo de seleção da rainha e a época de avaliação para as áreas de cria operculada, mel e total de alimento. O grupo selecionado para geleia real apresentou maior área de cria operculada e menor área de mel aos 90 dias. A infestação por varroa foi menor (p < 0,05) aos 90 dias. No experimento II, não foi encontrado interação para as características avaliadas. As áreas de cria operculada, total de cria e total ocupada da colônia apresentaram efeito do tipo de seleção da rainha e época de avaliação. A alta umidade relativa do ar influenciou o maior armazenamento de mel para o grupo local. Os diferentes grupos de rainhas responderam diferentemente em função do ambiente onde estão inseridas.(AU)