*2.3.3.1 Sib selection*

The selection of individual based on the sibs performance not including individuals own performance.

Based on its sib performance it is of 3 types:


HS selection is preferred over FS selection:


Breeding value of sib selection:

$$\text{PBV} = \overline{\mathbf{P\_c}} + \text{rh}^2 \frac{\mathbf{n}}{\mathbf{1} + (\mathbf{n} - \mathbf{1})\mathbf{t}} \text{ (}\overline{\mathbf{P\_s}} - \overline{\mathbf{P\_c}}\text{)}$$

Where, *P* - Average of contemporaries, *Ps* - average of sibs, n- number of sibs, r- coefficient of relationship (1*=*<sup>2</sup> for FS and <sup>1</sup>*=*<sup>4</sup> for HS), t- intra-class correlation (rh<sup>2</sup> ) among sibs (1*=*<sup>2</sup> for FS and <sup>1</sup>*=*<sup>4</sup> for HS), h<sup>2</sup> - heritability of the traits, h<sup>2</sup> s heritability of sibs = nh2 <sup>1</sup>þð Þ <sup>n</sup>�<sup>1</sup> <sup>t</sup>*:* [18]

Breeding value of Family selection:

$$\mathbf{PBV} = \overline{\mathbf{P\_s}} + \mathbf{h}^2 \left| \frac{\mathbf{1} - \mathbf{r}}{\mathbf{1} - \mathbf{t}} \left( \mathbf{P\_1} - \overline{\mathbf{P\_s}} \right) \frac{\mathbf{1} + (\mathbf{n} - \mathbf{1})\mathbf{r}}{\mathbf{1} + (\mathbf{n} - \mathbf{1})\mathbf{t}} \left( \overline{\mathbf{P\_s}} - \overline{\mathbf{P\_{cs}}} \right) \right| $$

Heritability of the trait:


## *2.3.3.2 Advantages of family selection*


#### *2.3.3.3 Disadvantages of family selection*


## *2.3.4 Progeny selection*

The selection criteria for evaluating an individual based on his progeny performance is known as Progeny selection or progeny testing. Progeny testing is the most important and one of the best criteria of selection. It is regarded as a form of family selection since progenies are the family members of each other. Progeny selection is very useful in the case of sex-limited traits. Such traits are milk yield and fat percentage in cattle and goat, litter size and litter weight at weaning in pigs and egg production in poultry etc. [20]. Progeny selection is also useful for the evaluation of an individual for carcass quality traits which could only be recorded after slaughter. The various functions or equations (sire indices) are used for the estimation of

breeding value of individual. The accuracy of progeny testing is depending on number of progenies tested, heritability of traits and the environmental correlation between the records of different progeny [5].
