The impact of controlling diseases of significant global importance on greenhouse gas emissions from livestock production

Table 5 Baseline poultry performance parameters

Performance parameter	Value
Mature hen bodyweight (kg)^a	1.00
Age at maturity (mo)^a	6.28
Age at culling (mo)^b	55.2
Annual eggs produced per hen^a	102
Proportion of eggs that are fertile^a	0.62
Proportion of eggs that are hatchable^a	0.64
Proportion of hatched chickens that survive to slaughter weight^a	0.45
Annual total chickens per hen that survive to slaughter weight (birds)^c	18.2
Chicken age at slaughter (d)	112
Chicken slaughter weight (kg)	0.90
Chicken carcass weight (kg)^d	0.63
Mean number of growing chickens in the flock per hen (birds)^e	5.51
Proportion of hen liveweight in the population^f	0.29
Proportion of growing chicken liveweight in the population^g	0.71
Potential growing chickens lost per hen death (birds)^h	9.0
GHGe per kg chicken meat (kg CO₂eq)ⁱ	6.60
GHGe per kg chicken meat attributed to hens (kg CO₂eq)^j	1.88
GHGe per kg chicken meat attributed to growing chickens (kg CO₂eq)^j	4.72

^a[25]
^b[26]
^c[25, 27, 28]
^d Calculated at 70% dressing percentage
^e Calculated from the number of growing chickens surviving to slaughter and the average laying pattern across the year
^f Calculated from the number of growing chickens surviving to slaughter, the average weight and slaughter age of growing chickens, and hen liveweight
^g 1 – the proportion of hen liveweight in the population
^h Calculated from live chicks hatched per year. the chicks that would otherwise have been hatched in the time taken to rear a hen replacement (age at first laying) and the CW yield of poultrymeat per animal
ⁱ[11]
^j Calculated based on relative proportions of bird liveweight within the population

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