GENETICS ▶▶▶


An example of a male with a fleshing score of 3.


Figure 3: Hatchability and male fleshing conditions of 23 flocks and 15,000 males.


Comparison of male condition and hatchability percentage


100,0 80,0 60,0 40,0 20,0 0,0


23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 Fleshing Score


Score 1 Score 5


Score 2 Average hatch %


Score 3 Cobb std hatch % Score 4


Figure 4 - Insufficient weight gain has a negative effect on fertility of 6 flocks and 3,000 males.


Comparison of male weight gain and fertility


250,0 200,0 150,0 100,0 50,0 -


(50,00) (100,0)


F15 weekly gain Fertility %


24


Std gain 3 per. Zw. Gem. (F15 weekly gain)


▶ POULTRY WORLD | No. 2, 2022 100% 95% 90% 85% 80% 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 75% 70%


fleshing scores developed rather quickly from 23 to 35 weeks of age. Scores 3 and 4 increased too rapidly. The thinner males with scores 1 and 2 were well managed as their num- bers declined and they remained a small proportion of the population. This would indicate that these males were re- moved. The remaining males with a score of 3 reached a point at 35 to 40 weeks where their fleshing scores rapidly in- creased to 4 and 5, with a corresponding decline in score 3 males. This was the result of early and rapid increases in feed allocation over 32 weeks. Ideally, 70% of males should score 3 for as long as possible for optimum fertility. Hatchability data was plotted against the fleshing scores as a graph in Figure 3. It is interesting to note that the decline in hatchability began at around the same time as the decline in score 3 and corresponding increases in scores 4 and 5. This indicated that the males became too heavy to continue mating, and over time the hatchability declined as the males developed bigger breast muscles. Based on the data, it was determined that males were being overfed in early produc- tion (23 to 32 weeks). Therefore, future feed intakes could be adjusted to control early muscle development and improve hatchability by conditioning males after 40 weeks. Another important key performance indicator for males is their weekly weight gain. After 32 weeks, they should gain very little weight (20 to 25 grams per week) and even large males should continue to grow. In Figure 4 it can be seen that the males had good weekly weight gains for a few weeks af- ter 30 weeks but that at around 35 weeks, the weight gains ceased abruptly. At that point, they started losing condition, so much so that by 40 weeks they were losing weight. The de- cline in growth or weekly gains after week 36 had a direct im- pact on the fertility percentage which dropped by 4%.


Implementing in future flocks As seen from these examples, it is important to record meas- urable performance data. When there is a sudden change in production, the data can be used to identify the cause and prevent it from recurring in future flocks.


% of males


PHOTO: COBB


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