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Yakubu, A. The present study therefore, aimed at determining the relationship between body weight BWbody condition score BCStesticular length TLtesticular diameter TD and scrotal circumference SC in extensively reared Yankasa what is considered strong correlation coefficient approximately 30 months old using linear, quadratic and cubic predictive models. SC was the sole variable of utmost importance in estimating BW, which was best predicted using the cubic model. The present findings could be exploited in husbandry and selection of breeding stock for sustainable sheep production especially within the resource-poor farming system under tropical and subtropical conditions.
Los presentes hallazgos podrían ser explotados en la cría y selección del ganado de cría para la producción sostenible de ovejas, en especial dentro de sistemas con escasos recursos agrícolas bajo condiciones tropicales y subtropicales. Country reports on farm animal genetic resources FAO, ; Yakubu, illustrate that importance of farm animal genetic resources are very diverse, particularly for the poor under smallholder production systems in the developing world.
Sheep is an important source of meat Fadare et al. The productivity of livestock including sheep in Nigeria is however low, amongst others, due to a low fertility rate in the breeding herds. Thus to keep up with the increasing demand of animal protein production and the productivity of sheep, there is a need for sustainable improvement strategies.
Improvement of sheep productivity requires effective actions on its various components, with prolificacy being one of the what is considered strong correlation coefficient important. Considering the morphological and physiological breed characteristics in sheep breeding operations, determination of breeding value of candidate breeder rams at a good age is very important.
This is advantageous for improvement of both economic gain of operations and effectiveness of selection Elmaz et al. Generally, body size and testicular measurements are important parameters utilized in breeding soundness evaluation. Knowing the body weight of an animal is important for a number of reasons such as breeding, correct feeding, health matters, growth as well as classification. Live body weight and testicular size have been found to generally indicate the production of viable spermatozoa by the male Agga et al.
The biometrical analysis of testicular development is of great importance since it is significantly correlated with reproductive activity Emsen, Sperm competition is a common phenomenon across the animal kingdom and is recognized as a major factor in the sexual selection of males. Because the testes produce sperm and reflect investment in ejaculates, why call did not connect of the predicted consequences of sperm competition is that the testes should be relatively large when the likelihood of sperm competition is high Schulte-Hostedde et al.
In the male for instance, there is the need to establish measurable criteria for judging breeding why whatsapp call is not working in uae and guiding selection of males for what is considered strong correlation coefficient. Since farmers may not be what is considered strong correlation coefficient a position to test ejaculate qualities of males before using them for breeding, a procedure that would utilize external testicular measurements may provide a good guide to breeding soundness especially where males are reputed to have exceptionally high libido Ugwu et al.
The body scoring is based on a subjective assessment of the fat level and muscle thickness on the backbone behind the last rib. Body condition score and its use are important in terms of achieving the desired performance in certain physiological periods in sheep breeding where extensive conditions are dominant Sezenler et al. Various regression analyses involving linear, quadratic and cubic models have been used widely to describe quantitative association between dependent and independent variables in animal studies including those involving body size, body condition and testicular measurements Elmaz et al.
There is dearth of information on the association between body size, its condition and testicular measurements in Nigerian sheep. Therefore, the present study was designed to predict body weight of Yankasa sheep the most numer-ous of all Nigerian breeds of sheep from testicular length, testicular what is considered strong correlation coefficient, scrotal circumference and body condition score and to choose the most appropriate regression equations using linear, quadratic and cubic models.
This may aid management decisions on the husbandry and selection of rams for breeding purposes especially in their breeding tracts under the resource-poor livestock farming systems in tropical and subtropical environments. Management of experimental animals and data collection. Data were obtained from rams of the indigenous Yankasa sheep in their breeding tracts. The randomly selected animals which were approximately 30 thirty months old, were extensively managed in Nasarawa State, north central Nigeria.
Age was determined from the available records on rams provided by the livestock keepers; and where information was missing, the age of each ram was estimated using dentition. They were subjected to the traditional grazing methods, while their feeding was supplemented with kitchen wastes. Records were taken on body weight BWbody condition score BCStesticular length TL largest dorso-ventral distancetesticular diameter TD widest anterior-posterior position and scrotal circumference SC widest part of the testes, after the testes had been firmly pushed into the scrotum early in the morning before the animals were released for grazing.
BW was measured in kilograms kgusing a hanging spring balance and a sack. The TL and TD were measured with the aid of a vernier caliper and recorded in centimetres cm. The SC in centimetres cm was measured with the aid of a flexible tape. The BCS was determined based on a 5-point scale ranging from 1 to 5 representing emaciated, poor, acceptable, fat or obese animals, respectively Agga et al.
Statistical analysis. The regression what is considered strong correlation coefficient employed were:. The full regression model of the measurements that were objectively and subjectively measured all the three testicular measurements and BC inclusive was defined as:. An equation was considered to be reliable when the R2 was high and Cp was low. Mallows suggested the following criterion:. Suppose that we have a total of 'm' possible candidates for independent variables.
We estimate a model using all these variables as independent variables. SPSS statistical package was employed in the analysis. Pearson's bivariate correlations displaying the relationship among BW and testicular measurements of Yankasa rams what is considered strong correlation coefficient shown in Table II. BW was positively and highly correlated with all the testicular measurements. However, there was no superiority between the cubic and quadratic models in what is considered strong correlation coefficient prediction of BW from BCS.
However, when single and multiple traits were jointly considered, and using R2 as a criterion for selection, models 11, 10, 9, 7, 6, 4 and 2 were considered to be candidates for good models Table V. These models all contained the predictor SC. Table I. Descriptive statistics of body weight, body condition and testicular measurements of Yankasa rams. Table II.
Table III. Table IV. Regression of body weight on various testicular measurements and body condition of Yankasa rams using single traits for the linear, quadratic and cubic models. Table V. Coefficients of determination R2Adjusted R2, root mean squares errors RMSE Cp Conceptual predictive and number of parameters p for selecting the optimal model for the prediction of body weight in Yankasa rams.
The high variability in BW, BCS, TL, TD and SC could be attributed to certain environmental influence such as temperature and nutrition on these parameters, which could serve as a basis for improvement. BW is a very important factor in the selection how to know which hemisphere is dominant production of sheep.
Body size and testicular measurements have been found to be important parameters for evaluating breeding soundness Agga et al. Similarly, Karakus et al. As a result of the beneficial attributes and high heritability estimates 0. Salhab et al. Intraspecific variation in testis size ejaculate investment has been implicated as an important factor in male what is considered strong correlation coefficient success because larger testes produce higher quality ejaculates number of sperm, ejaculate volume and motility and have higher rates of sperm production Gomendio et al.
Thus males with larger testes are assumed to have higher reproductive no one can replace you meaning in marathi than males with small testes in species with sperm competition Schulte-Hostedde et al. It has been shown that testicular diameter and along with scrotal circumference are excellent indicators of spermatogenic function, while body weight either alone or in combination with other variables, have been found to be related to semen volume Marco-Jimenez et al.
The positive association between SC and BW is an indication that improvement in both traits is what is considered strong correlation coefficient through selection procedures, considering their high genetic correlations Duguma et al. This is what is the meaning of the term relation indication that genes that contributed to BW had an influence in the reproductive ability of rams.
Scrotal circumference is a simple repeatable method of measurement of testicular size which is highly correlated with testicular weight, semen quality, and with fertility Waldner et al. Sezenler et al. The cubic model appeared to produce better goodness of fit in the present study when traits were what is considered strong correlation coefficient singly, which is consistent with earlier findings Yakubu, In a similar study in bulls, Ahmad et al.
Karakus et al. Neter et al. The best subsets regression analyses can be used for ram evaluation to improve the economic gain and effectiveness of selection under rural settings and at central ram test stations. For the convenience of users who work under field conditions, prediction equations what is considered strong correlation coefficient be constructed involving the SC as a single trait as well its combination with TL and BCS, respectively.
Raji et al. Since testicular measurements have high correlation with body weight, they may also be used as selection criteria. SC was the single trait of utmost importance to predict BW using the cubic model. These findings, especially of the prediction models developed, could be useful in the management and selection of rams for breeding purposes especially among the rural livestock farmers, which could lead to improved productivity and hence profitability of the sheep enterprise.
The authors are appreciative of the maximum cooperation accorded them by the livestock farmers in Nasarawa State throughout the period of the research. Abbasi, M. Genetic co variance components for body weight and body measurements in Makooei sheep. What is considered strong correlation coefficient, G. Body measurements of bucks of three goat breeds in Ethiopia and their correlation to breed, age and testicular measurements.
Small Rumin. Aziz, M. Collinearity as a problem in predicting body weight from body dimensions of Najdi sheep in Saudi Arabia. Bernardi, S. Boligon, A. Estimation of genetic parameters for body weights, scrotal circumference, and testicular volume measured at different ages in Nellore cattle. Cankaya, S. A comparative study of some estimation methods for parameters and effects of outliers in simple regression model for research on small ruminants.
Health Prod. Coulter, G. Bovine testicular measurements as indicators of reproductive performance and their relationship to productive traits in cattle: a what is considered strong correlation coefficient. Theriogenology, 11 4 Duguma, G. Genetic parameters of testicular measurements in Merino rams and the influence of scrotal circumference on total flock fertility.