NUTRITION ▶▶▶
Significance of maintenance energy requirement in breeders
BY STEVE LEESON, UNIVERSITY OF GUELPH B
roiler breeders are usually fed around 160 g/bird/ day at peak production to meet an energy require- ment of around 450-475 kcal/day. The actual quan- tity of feed allocated will obviously vary with diet
energy level, although this is usually within the limited range of 2750-2850 kcal/kg. Breeders, like most farmed poultry, will eat to their energy requirements if given free-choice feed al- though this never happens under commercial conditions, even with the lowest energy concentration possible. The lay- ing hen, on the other hand, can adjust its feed intake in re- sponse to changing energy needs and so commercial diet en- ergy levels are much more variable. With restricted feeding regimes for breeders we dictate feed and nutrient intake and, consequently, much more thought has to go into estimating fluctuating and evolving daily nutrient needs.
Calculating energy and feed needs The main nutrients considered in formulating breeder diets are energy, amino acids, calcium and phosphorus. Even with the ever-declining levels of protein and amino acids fed to breeders today, it’s highly unlikely that we underfeed amino acids in terms of needs for egg production. Arguably, we are
Most of our breeder feed is used to meet maintenance requirements and, as such, some 70% of the overall feed cost gives no tangible return. However, failure to meet this critical maintenance need will invariably be at the expense of reduced egg production.
perhaps reaching the lower limit for amino acids needed for feathering but this issue is confounded with concomitant use of any additional amino acids for muscle deposition (growth). Estimates of daily feed allocations for breeders are therefore usually based on meeting energy requirements. As with any bird, energy is required for maintenance and production, with the latter comprising growth and egg formation. We invaria- bly focus our attention on meeting needs for egg number and size but this is a minor component in overall energy needs. The following equation is used to indirectly estimate feed needs based on coefficients related to energy use for maintenance, growth and egg mass production.
Evolving equation Daily feed intake (g/b/d) = [((120*W.75)+(W- G*3.6)+(EM*2.6))/2.85]+(26-T), where W = body weight, kg,
Table 1 – Calculation of breeder feed intake at 26˚C (2850 kcal/kg diet). Weeks age
24 28 32 36 40 45 50 55 60 65
Body weight (kg) 2.60 2.90 3.30 3.60 3.70 3.80 3.85 3.90 3.95 4.00
Weight gain/d 11 14 11 4 4 2 2 2 2 2
Egg prod (%) 3
80 83 82 77 75 68 61 56 50
Egg weight (gr) 50 57 62 65 66 67 68 69 70 71
Metabolic wt
2.05 2.22 2.45 2.61 2.67 2.72 2.75 2.78 2.80 2.83
Egg mass (g/d) 1.5
45.6 51.5 53.3 50.8 50.3 46.2 42.1 39.2 35.5
Feed g/b/d 101 153 164 163 163 163 160 158 158 154
▶ POULTRY WORLD | No. 7, 2022 9
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