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Scientific Journal of Zoology
Number of Followers: 6

This is an Open Access Journal

Open Access journal
ISSN (Print) 2322-293X
Published by Sjournals

[11 journals]

Morphology and its relationship with reproduction and milk production in
goat and sheep
- Authors: Never Assan
  Abstract: Morphological characterisation and multifactorial analyses of conformation traits in relation to productivity indicators are critical in goats and sheep breeding programs in particular, as the desired outcome could instigate animal performance change through indirect selection based on the phenotypic measurements. Animal morphology development is complex biological process probably with multiple genes being at play, which might be dependent on the environment, and changing over time, hence recording multiple descriptive morphological dimensions can make relating genotype to phenotype more feasible and, importantly, more relevant in terms of understanding functionality of domestic animals. Morphological traits sometimes referred to linear type traits, biometric, zoometric and conformation traits (measurements) have been of interest in both livestock and poultry production. Due to the fact that some morphological traits are highly correlated to performance traits, their application in animal production among other aspects include: prediction of growth rate, body condition, carcass and milking capacity. This implies that morphological traits correspond to functionality of animals for the purposes of production as a result they have been a useful tool in selection of animals, especially where records are unavailable. Morphological traits can be extremely valuable in animal breeding decision making since they can be used to derive specific scores for heritable traits. In most cases, in view of simplicity of measurement, morphological traits have been part of performance recording appraisal systems. This has worked well to overcome the gap that exist in keeping performance records especially in community based breeding schemes. In most cases records in smallholder production systems are unobtainable hence morphological dimensions become handy for selection purposes. Some of the morphological traits have proved to be the source or representative group of suitable selection markers to elaborate the appropriate breeding program to improve the reproduction and milk production potential of goats and sheep. If morphological traits are to be regarded for incorporation in prospective goat and sheep breeding programs, the relationship between them and reproduction and milk production need to be established. In the advent of multiple regression models the prospects are high to establish correlation analysis between morphological traits with production traits in goats and sheep. In conclusion, the review verified that morphological traits can be used as accurate indicators of animals’ reproductive capacity and milk production potential in goat and sheep production. The purpose of the present review is to highlight the relationship between morphometric characteristics and reproductive and milking potential in goats and sheep production.
  PubDate: 2020-03-20
  Issue No: Vol. 9, No. 2 (2020)
Aspects of litter size (birth type) in goats and sheep production
- Authors: Never Assan
  Abstract: Increasing kid/lamb production is of paramount importance to goat and sheep producers. As a matter of one choice enhancing litter size becomes inevitable, because apart from litter size impacting on flock productivity, it is also implored as a major determinant of profitability due to its influence on kid/lamb survivability. There is a positive correlation between litter size and lifelong dam contribution and overall flock productivity. Increasing litter size to an optimal level might be crucial especially for the intensive goat and sheep production systems. A number of studies have proved that litter size is under the influence of both genetic and non-genetic factors. Currently, genome wide selection targeting established genetic markers is being employed to increase the efficiency of goat and sheep selection for reproductive traits, such as prolificity. This is on the background that litter size is lowly heritable, but on the other hand, immense genetic variability between and within breeds exist that could be exploited in breeding schemes by collaborating additive polygenic differences, breed complementarities, heterosis effects and major gene inheritance. Among the non-genetic factors that influence litter size in goats and sheep, parity order, age of dam and seasonal variation have been rated highly. Litter size tend to improve with age and parity order as a result it is highly likely that dams with large previous litter size may have high chances of producing multiple births in consecutive kidding/lambing. Environmental conditions are also an important source of variation on litter size, with chances of large litter size within natural reproductive seasons. Seasonal influence might be confounded by other factors such as flock nutritional management and genetic improvement strategies. The adverse effect of increase in litter size has been associated with an increase in number of underweight kids/lambs which in turn lower their survival rates. Underweight at birth is the probable explanation for reduced kid/lamb viability in goats and sheep. This entails a balance should be strike on optimal litter size, where too large and/or too small litter size may be impracticable desired and/or uneconomical, respectively. Proffered suggestion is that litter size of two is economically feasible for an intensive goat and sheep enterprise. The present review gives an insight on the influence of litter on flock performance and discuss the factors that are the major determinants of litter size in goat and sheep meat production.
  PubDate: 2020-03-15
  Issue No: Vol. 9, No. 2 (2020)