Bonus Tydskrif AUTUMN 2024

The most effective solution is making sure the pullets are reared correctly. Early bodyweight development and carcass composition are highly correlated with laying performance later in the hen’s life. Table 1 shows the correlation between the bodyweights of pullets at five and ten weeks of age, and the uniformity of the flock at 16 weeks of age with laying performance of the hens. The bodyweight of the pullets at age five weeks is highly correlated to the laying performance of all variables measured. The reason for this is that this is the period in the bird’s life when the development of the skeleton, muscles and internal organs occurs as is shown in Figure 2. The five-week weight is a very good indication of whether this has been achieved. Figure 1: Development of skeleton, muscles and internal organs in pullets at age five. Table 1: Correlation between the bodyweights of pullets five and ten weeks of age. variables measured. The reason for this is that this is the period in the bird’s life when the development of the skeleton, muscles and internal organs occurs as is shown in Figure 2 . The five-week weight is a very good indication of whether this has been achieved. Table 1: Correlation between the bodyweights of pullets five and ten weeks of age. Bodyweight at five weeks Bodyweight at ten weeks Uniformity at 16 weeks % laying rate between 20-24 weeks of age +++ 0,63 +++ 0,59 0,00 % laying rate between 68-72 weeks +++ 0,82 0,00 ++ 0,46 Amount of eggs produced up to 60 weeks of age +++ 0,83 ++ 0,30 +++ 0,54 Amount of eggs produced up to 72 weeks +++ 0,93 0,00 +++ 0,72 Liveability up to 72 weeks of age +++ 0,71 0,00 ++ 0,40 +++ Very high correlation ++ High correlation + Low correlation 0 No correlation Figure 2: Development of skeleton, muscles and internal organs in pullets at age five weeks. Bodyweight at ten weeks of age is not as highly correlated with laying performance, except for the period up until peak production. The uniformity of the flock at 16 weeks of age is correlated to the rate of lay when the hens are older (persistency) and the number of eggs that they will lay over their lifetime due to better liveability. The bodyweight of pullets at the start of sexual maturity determines the average egg weight. Not achieving the target bodyweights during rearing and poor uniformity at sexual maturity can be the cause of several problems in the laying flock: • An increased risk of vent prolapses from 18 to 30 weeks of age, during the peak laying period. • Taking longer to achieve the desired mature bodyweights. • A shorter laying peak. • Failure to sustain high peak laying rates post-peak laying persistency. • More smaller eggs laid during the early part of the laying period. • Egg size will be smaller over the entire laying period. The De Heus recommendation is to rear the pullets to be 5% heavier than the bodyweight target recommended by the breed company up to point-of-lay. They usually recommend a bodyweight target band between a lower and upper target weight; this can be achieved by growing the birds on the upper Bodyweight t ten weeks of age is not as highly correlated with laying performance, except for the period up until peak production. The uniformity of the flock at 16 weeks of age is correlated to the rate of lay when the hens are older (persistency) and the number of eggs that they will lay over their lifetime due to better liveability. The bodyweight of pullets at the start of sexual maturity determines the average egg weight. Autumn / Herfs 2024 BONUS www.agribonus.co.za 50