ABSTRACT. The factors related to cannibalistic behavior of dams in a Wistar rat colony are identified and analyzed. The maternal genetic effects were tested as a random effect by the method of generalized linear models. The season at parturition, the dam´s age at parturition and the density of the room at parturition were tested as fixed effects, whereas the litter size at birth was tested as a co-variable. The genetic effect of the dam was significant for the number of cannibalized pups. Although the season at parturition, the dam´s age and room density on the day of parturition were not individually significant (p > 0.05), most of the interactions between the variation sources were significant (p < 0.05). Cannibalism occurred mostly in dams aged over 241 days, with parturition during spring. So that occurrences of cannibalism could be avoided, dams with the smallest number of cannibalized pups should be selected, coupled to dams younger than 241 days, breeding during spring. The above strategies may reduce the number of couples in the vivarium and increase their production efficiency.Keywords: laboratory animals, maternal behavior, infanticide, rodents.Efeito do ambiente e da matriz sobre o canibalismo em filhotes de ratos Wistar RESUMO. O objetivo deste estudo foi identificar os fatores relacionados ao comportamento de canibalismo das fêmeas em uma colônia de ratos Wistar. Os efeitos genéticos maternos foram testados como efeito aleatório usando o método dos modelos lineares generalizados. A estação do parto, a idade da fêmea ao parto e a densidade da sala ao parto foram testados como efeitos fixos e o tamanho da ninhada ao nascimento foi testado como covariável. O efeito genético da matriz foi significativo para o número de filhotes canibalizados. A estação do ano ao parto, a idade da matriz e a densidade da sala no dia do parto quando testados separadamente não foram significativos (p > 0,05), porém, a maioria das interações entre estas fontes de variação foram significativas (p < 0,05). O canibalismo ocorreu em maior frequência em fêmeas com idade superior a 241 dias durante a primavera. Para evitar o canibalismo na população estudada, recomenda-se a seleção de fêmeas com menor número de filhotes canibalizados e a maior utilização de matrizes com idade inferior a 241 dias durante a primavera. Estas estratégias podem promover a redução do número de casais necessários no biotério e aumentar sua eficiência reprodutiva.Palavras-chave: animais de laboratório, comportamento materno, infanticídio, roedores.
The aim of the present study was to estimate heritabilities and evaluate the existence of genotype-environment interactions for growth curve parameters in quail fed diets containing different threonine:lysine ratios. A total of 4,441 body weight information from two genetic quail groups (LF1 and LF2) fed diets containing 0.66%, 0.71%, 0.76%, 0.81%, and 0.86% threonine:lysine ratios from hatching to 21 d of age were evaluated. From 22 to 35 d of age, quail received a single diet. The Gompertz model was used to estimate growth curve parameters. Genetic analyses were performed using random regression models, by Legendre polynomials of the second kind, considering homogeneity of residual variances. The following characteristics were evaluated: asymptotic weight, asymptotic growth rate, and inflection point. Increases in threonine:lysine ratios promoted higher heritability estimates for these variables in the LF1 genetic group compared to LF2, which indicates that the additive genetic variation was modified due to the environmental variation influenced by the evaluated amino acid ratios, with differences between both genetic groups. Thus, it is recommended that quail be selected in the 0.86% ratio in genetic group LF1 and 0.66% in genetic group LF2, where greater heritabilities were observed. Dispersion of individual breeding values along the environmental gradient was observed for all evaluated characteristics, in both genetic groups, suggesting the existence of genotype-environment interactions for these variables. The evaluated amino acid ratios should be considered in quail breeding programs, since breeding value predictions for a determined threonine:lysine ratio are not valid for other ratios.
The Holstein and Jersey dairy cattle breeds are among the most prevalent in Brazil. To evaluate differences among the PTAs (predicted transmitting abilities) of these breeds and their lines, data were collected on 385 Holstein bulls and 82 Jersey sires with semen commercially available from nine Brazilian companies. Three different sire lines for each breed were found. The general linear models method was used for the comparison among lines and between breeds. The two most prevalent lines of Holstein breed presented higher average PTAs for milk yield (1,061.04 pounds and 975.32 pounds) and lower PTAs for percentage of milk solids (from -0.05% to -0.0003%) (P<0.05). These results indicate the supply of sires that mostly increase the milk yield in the Brazilian market. The Jersey breed presented a higher inbreeding coefficient (6.62%) than the Holstein breed (5.14%) (P<0.05). Although the Holstein breed presented higher PTAs for milk yield and lower PTAs for percentage of milk solids (P<0.05), the productive life of the Jersey breed (1.17 months) was longer than it was in the Holstein breed (0.40 months) (P<0.05). We identified the existence of an important variability of the available genetic profiles, what allows the Brazilian producers to choose the most adequate semen for their production system. It is necessary to consider the genetic profiles of sires' lines offered for artificial insemination in Brazil to understand and direct the genetic pattern of Brazilian dairy cattle.
The goals of this research were to estimate the phenotypic correlations among various meat quality traits from a male broiler line and to describe the relation among these variables. Phenotypical correlations were determined among
The aim of this study was to evaluate images captured using a drone to determine the presence of estrus detection adhesives in bovine females. 56 healthy, reproductive age and extensively reared cows were used. An adhesive was attached to each female in the region of the caudal insertion to detect estrus. The animals were divided into seven experimental groups (n=8), as follows: Group 1 (control) -females without adhesive; Group 2 -females with adhesive without any scraping area (100% gray); Group 3females with dark rump coat with 50% green shaving adhesive; Group 4 -females with dark rump coat with 50% orange shaving adhesive; Group 5 -females with pale rump coat with 50% green shaving adhesive; Group 6 -females with pale rump coat with 50% orange peel adhesive; Group 7 -females with dark rump coat with 25% orange shaving adhesive. The presence, color and degree of scraping of the adhesive were analyzed according to the influence of flight time and height, coat color and the presence or absence of clouds at the time of image capture. Data were submitted to analysis of variance and means to Tukey's test, at 5% significance. There was a statistical difference for the color of the sticker in relation to flight time and coat color (P<0.05), and the flight performed in the late morning and the animals with dark-haired rump showed the best results. The analysis of photographs obtained using a drone showed reliable applicability in bovine females.
The goal of this study was to evaluate the effect of the donor and the months of the year on the oocyte recovery rate in Senepol donors. Data on 604 follicular aspirations guided by ultrasound, performed on 33 healthy cows aged between two and seven years were evaluated. Data were made available through individual spreadsheets by a commercial company. All donors belonged to the same batch and breeding farm and were kept under the same food management. Viable and degenerate oocyte recovery rates and the effect of the month of collection and the individual factor of the donor were analyzed. Data were tested by analysis of variance (ANOVA) followed by Tukey's test, with a significance level of 5%. A significant number of total (27.13 ± 14.38) and viable (23.17 ± 12.94) oocytes was observed. The number of grade I oocytes was high among the donors, and the number of total and grade II and III oocytes were the least altered between the months evaluated. There was an excellent number of oocytes recovered, with variation observed according to the donor and the month of the year evaluated.
The aim of this study was to estimate genetic parameters and genetic trends for reproductive traits in Wistar rats. A total of 1,167 data records from 283 females over six generations of monogamous mating pairs was used. Heritability and genetic correlation were estimated through Bayesian inference and genetic trends were calculated by linear regression of breeding values over generations. Heritability estimates for litter size at birth (LS), calving interval (CI), pup mortality (PM) and maternal cannibalism (CAN) presented low magnitude, ranging from 0.01 to 0.13. CAN presented high and positive genetic correlation with LS and PM (0.77 and 0.78, respectively). On the other hand, all the other estimated genetic correlations were not significant. Genetic trend was positive for LS (+0.0900 pups per generation), and negative for PM and CAN (-1.0085 and -0.5217 pups per generation, respectively). For CI the genetic trend was not significant. It is recommended to increase selection intensity on dams in this Wistar rat population in order to accelerate the genetic progress.
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