ABSTRACT
The aim of this study was to develop prediction equations for the body weight of Pelibuey ewes from body measurements comparing linear vs nonlinear models. A subsample of 197 ewes was scored for body weight (BW), rump length (RL), rump width (RW), height at withers (HW), chest girth (CG), chest width (CW), chest depth (CD), cannon bone perimeter (CP), and body length (BL). Pearson's correlation analysis was performed on a sub-data set from 197 ewes to estimate the relationship between body weight and body measurements. Multiple linear regressions were fitted to obtain prediction equations of body weight from the eight body measurements, and prediction equations were obtained from the body measurement that showed the highest correlation with body weight using five nonlinear models allometric, saturation growth, exponential, and incomplete gamma. Data from an independent subsample of 196 ewes was used to validate the equation with the best goodness of fit using linear regression analysis. CG was the body measurement that showed the highest correlation with BW, and based on multiple stepwise regression, in the equation BW = - 60.622 + 1.233CG explained 79% of the body weight variation. Moreover, BW prediction was more accurate when other measurements such CW, BL, and RW were added to the model generating to the equation BW = - 68.875 + 0.845CG + 0.866CW + 0.195BL + 0.601RW (R2 = 0.85, MSE = 15.51). In the case of nonlinear models, incomplete gamma and exponential models generated the equations with the best goodness of fit and precision: BW = 0.077CG1.108exp(0.016CG) (R2 = 0.82, MSE = 18.64) and BW = 3.5759exp(0.0292CG) (R2 = 0.82, MSE = 18.65) respectively.
Subject(s)
Body Weight , Sheep , Animals , Female , Linear Models , Regression AnalysisABSTRACT
A study was conducted with the objective to characterize the morphology of Pelibuey sheep in the state of Colima, Mexico. A total of 386 sheep were scored for 12 body measurements in addition to live weight and five racial and eight functional indices were calculated. The influence of sex on the body measurements and indices was analyzed, and morphological harmony was determined through Pearson correlation. The sexual dimorphism was 1.21, with males being 67 % heavier than females. Females and males had a high and moderate degree of harmony in their morphological model, respectively. Pelibuey sheep were dolichocephalous, tended to be medium- to large-sized according to the thoracic index, with a convex curve rump; they were a homogeneous breed, well adapted to environmental and production conditions of the state of Colima, Mexico, and show an undefined zootechnical aptitude and therefore a great potential to be oriented towards meat or milk production through genetic selection or terminal crossbreeding systems using specialized breeds.
Subject(s)
Sex Characteristics , Sheep/anatomy & histology , Animals , Body Weight/physiology , Female , Male , Mexico , Statistics, NonparametricABSTRACT
A case study was conducted with the objective to describe and determine whether the occurrence of sheep poisoning was due to milkweed Asclepias curassavica or an acute case of gastrointestinal nematosis. Milkweed population and distribution as well as animal data such as grazing behavior and poisoning symptoms were collected in the field. A necropsy was carried out with the objective to describe histopathological findings in relation to the observed symptomatology and confirm poisoning diagnosis. Symptoms such as inability to stand, muscle paralysis, salivation, diarrhea, followed by facial edema and death, began when the animals grazed on native grass prairie with a scarcity of forage but a high density of A. curassavica. Nevertheless, the study of the grazing behavior in the area where there were intoxication cases showed only exploratory contacts between lambs and milkweed. Necropsy findings showed diffuse edema of the subcutaneous tissue (anasarca), serous fat atrophy, poor development of pale muscles, hydrothorax, hydropericardium, hydroperitoneum and abomasum containing blood, mucous, and abundant blood-sucking nematodes Haemonchus contortus with no evidence of poisoning. These findings indicated a severe mucohemorrhagic abomasum inflammation and generalized edema associated with a hypoproteinemia due to an acute haemonchosis as the cause of death.
Se realizó un estudio de caso con el objetivo de documentar la posible ocurrencia de envenenamiento por el consumo de Asclepias curassavica o de casos agudos de nematodiasis gastrointestinal en ovinos en pastoreo. Se registró la densidad de población, la ubicación espacial de la maleza y el tipo de vegetación; además, se observaron los hábitos de pastoreo del rebaño y la semiología mostrada por los ovinos afectados. Posteriormente se realizó una necropsia con la finalidad de describir hallazgos histopatológicos relacionados con la semiología observada, que confirmaran el diagnóstico de envenenamiento. El estudio de campo mostró que la aparición de signos característicos de envenenamiento, como incoordinación, parálisis muscular, salivación, diarrea, seguidos por edema facial y muerte, inició cuando los animales pastaban bajo condiciones propicias para la ingestión de la planta tóxica: mala oferta de forraje y abundante población de A. curassavica. El estudio de los hábitos de pastoreo en el área en que se presentaron los casos de intoxicación, sólo mostró acercamientos y consumos de A. curassavica de tipo exploratorio, mientras que la necropsia mostró un edema generalizado del tejido subcutáneo (anasarca) con atrofia serosa de la grasa y músculos pálidos con mal desarrollo, hidrotórax, hidropericardio, hidroperitoneo y abomaso con presencia abundante de sangre, moco y nematodos del género Haemonchus contortus sin evidencias de intoxicación. Se concluye que la muerte de los animales se debió a abomasitis mucohemorrágica severa difusa y edemas generalizados asociados con una hipoproteinemia causados por hemoncosis aguda.
