Breeder nutrition fundamentals in any poultry operation: recent developments in North Carolina

Many broiler breeders have been reared since we first began to explore the idea that something other than just body weight (BW) and uniformity, both important longstanding management paradigms, was involved in proper rearing of broiler parent stock.

Our original work was released in 1995 under the umbrella that we called the ‘concept of minimum cumulative nutrition’ that emphasized the form of the feeding program, long-term relative consistency of feeding, and coordination of age at photostimulation with cumulative nutrition targets (Peak, 1996; 2001; Walsh, 1996; Walsh and Brake, 1997; 1999). The minimum cumulative intake was found to be ~1,200 g crude protein (CP) and 22,000 kcal of metabolizable energy (ME) at ~140 days of age (~20 wk) for females, irrespective of BW. This minimum required that the total lysine, on a good quality corn-soy-based diet, be 5% of CP and methionine + cystine be 83% of lysine.

We now recommend that photostimulation be 7 days after reaching these targets to add approximately 2,000 kcal ME and 100 g CP to each of the cumulative totals. There may be a different minimum to obtain maximum broiler performance, as discussed below.

We have also determined 29,600 kcal ME and 1,475 g CP to ~21 weeks of age to be near the minimum cumulative nutrient intake for separate-grown males (Romero-Sanchez et al., 2007abc). Rearing nutrition minimums, irrespective of BW, must be very important as it has been demonstrated that genetic selection (i.e., pedigree level) on high density diets apparently necessitates good quality rearing diets in order for subsequent generations to fully express their reproductive potential. As suggested by Lilburn et al. (1992), parent stock must not be deprived of sufficient nutrition during rearing if reproduction is to be optimal.

A smooth transition between starter, grower and breeder diets should be considered during feed formulation and a single ME may be used for both growing and laying diets. A 15% CP diet with ~0.75% total lysine and ~0.60-0.63% methionine + cystine should be sufficient to support egg production without producing excessive amounts of breast meat. Such diets are satisfactory for both males and females. Separate male diets are not required.

The same level of CP and amino acids should be minimally sufficient for rearing diets. In fact, there has often been good reason to have higher density rearing diets than laying diets in order to ensure optimal economic results during the breeder laying period.

Our data and practical field experience show that large feed increases or large changes in diet density (i.e., more CP or ME in layer than in grower diets) late in rearing or during early lay for pullets result in excessive ‘fleshing’ (breast meat development).

Excess breast meat may increase maintenance requirements and inhibit reproductive development. Such birds tend to exhibit a reduced appetite in hot weather (even in tunnel-ventilated and evaporatively cooled houses), increased susceptibility to heat stress, and poor reproductive persistency.

Further, it has become increasingly apparent that cumulative nutrition and the feeding program during rearing and early lay can affect broiler breeder development and carcass conformation in such a manner as to affect egg weight, livability, feed consumption, and fertility, as well as performance of the broiler progeny. Precision feeding and nutrition are required.


Effects of broiler breeder nutrition and management on broiler progeny

Broiler progeny performance has long been recognized as being an important outcome of broiler breeder management, but data to clearly relate breeder management to broiler performance have been scarce. To evaluate vertical effects of cumulative nutrition during the pullet-rearing period on performance of broiler offspring, broiler chicks were hatched from Cobb 500 broiler breeders reared on three levels of cumulative CP and ME intakes (High (27,780 kcal ME and 1,485 g CP), Medium (26,020 kcal ME and 1,391 g CP), and Low (24,240 kcal ME and 1,296 g CP)) to 22 weeks (154 days) of age. The three pullet groups were fed the same rearing diets with cumulative differences achieved by varying the volume fed.

As points of reference, the daily feed amounts at 15 weeks of age were 67, 73, and 77.5 g per female for the Low, Medium, and High programs, respectively. This range of feed allocation would be expected to cover the normal feeding range, although feed allocations less than 67 g are often observed at 15 weeks of age and 77 g would be seldom observed. Males were grown sex-separate to a cumulative nutrient intake of about 30,000 kcal ME and 1,600 g CP. Males and females were fed sexseparately a single breeder laying diet from 25 weeks of age. Breeders were moved from a blackout rearing (8 hr of light) facility to the slat-litter laying facility and photostimulated (14 hr of light) at 22 weeks of age.

Pullets in the Low, Medium, and High treatments weighed 2,450 g, 2,550 g, and 2,660 g, respectively, at 22 weeks of age, but these differences rapidly disappeared during the laying period. Egg production, fertility, and fertile hatchability were very similar, while percentage shell and egg weight (Table 1) were not significantly affected.


Table 1.Effect of cumulative pullet nutrition during the rearing period on subsequent egg weight.


¹See text for details



Two broiler trials evaluated chicks hatched at 28 and 39 weeks of age, respectively, two ages that would be normally expected to produce chicks of different quality and with different broiler performance. Although there were no consistent significant effects of plane of pullet cumulative rearing nutrition on broiler feed conversion or mortality to 21 days of age, BW demonstrated an increase with increasing cumulative nutrition that was most pronounced for the 28-week broilers (Table 2). It was interesting to note that the male BW at 21 days of age was in the 900 g range, which was exceptional for broilers from a 28-week-old breeder flock.


Table 2. Effect of cumulative pullet nutrition during the rearing period on subsequent 21-day body weight.


¹See text for details



In spite of all efforts to manage flocks in such a manner as to have good uniformity of BW, significant variation among broiler breeder males has always been present. There will always be large and small breeder males and the feeding program and nutrition will be generally the same for all of the birds as the flocks move into the laying phase. Thus, the largest males will often be relatively underfed and may fail to gain BW consistently during the critical early breeding period, which has consistently caused reduced fertility.

Fertility has been found to be largely a function of the number of males mating in a flock. In the case where larger males were most likely not mating, as caused by a failure to gain BW, a lower broiler BW of up to 70 g resulted. The explanation for this phenomenon lies in the simple fact that the heaviest males must be the males that produce the heaviest broiler progeny, so that when the largest males do not mate the largest broilers will not be produced.

In fact, studies in our laboratory (Romero-Sanchez et al., 2007abc) have shown that whenever fertility declined in a broiler breeder flock due to underfeeding of males, there was an associated decrease in broiler progeny performance, generally 50-70 g. In a similar manner, Attia et al. (1993; 1995) showed that an increase in daily breeder male feed allocation of 80 kcal ME produced broilers that were 80 g larger.

It is also important to have sufficient micronutrients in the rearing and breeder feeds.

The breeders must have these micronutrients to deal effectively with the stress of restricted feeding during rearing and the females must be able to transfer sufficient nutrients to the embryo through the yolk sac during breeding. Micronutrients such as antioxidants can also have a beneficial effect on fertility through a number of well-described mechanisms although their nutrient-sparing activities have been of most interest in our experience. It has long been known that vitamin C works best during stress and in the presence of a marginal plane of nutrition. Vitamin E may function in a similar manner.

Our recent data strongly suggest that high amounts of selenium yeast (e.g., Sel-Plex®, Alltech Inc.) supplementation, in combination with vitamins C and E or alone, appears to function best when broiler breeders are receiving a less than adequate daily feed allocation (Table 3). As it would most likely be the largest males that exhibit reduced mating activity in the presence of such marginal nutrient intake, antioxidant therapy could result in increased broiler performance in a manner similar to that described above. However, precision feeding would be required to consistently achieve such results and avoid overweight breeders that would negate any beneficial effects.


Table 3.Broiler breeder fertility as affected by a combination of antioxidants comprised of Sel-Plex® selenium yeast, vitamin C, and vitamin E.


^a,bMeans differ (P<0.05).
^A,BMeans differ (P<0.001).
¹ Time by treatment (antioxidant level) interaction (P<0.0001).



Conclusion

The conclusion appears to be simple. The broiler breeder males that produce the progeny with the greatest genetic potential are the largest broiler breeder males and they must be fed in a programmed manner that achieves early sexual maturity and persistent fertility. In a similar manner, adequate nutrition during rearing, which prepares broiler breeder males and females to mature sexually in an optimum manner, has been shown to be absolutely required in order to obtain the best broiler performance.



References

Attia, Y.A., K.A. Yamani and W.H. Burke. 1993. Daily energy allotment and reproductive performance of broiler breeder males. Poult. Sci. 72:42-50.

Attia, Y.A., W.H. Burke, K.A. Yamani and L.S. Jensen. 1995. Daily energy allotments and performance of broiler breeders. 1. Males. Poult. Sci. 74:247-260.

Lilburn, M.S., J.W. Steigner and K.E. Nestor. 1992. The influence of dietary protein on carcass composition and sexual maturity in a random-bred population of Japanese quail (R1) and subline of R1 selected for increased BW. Comp. Biochem. Physiol. 102A:385-388.

Peak, S.D. 1996. A mathematical model to investigate nutritional influences on broiler breeder male fertility. M.S. Thesis, The Graduate School, North Carolina State University, Raleigh, NC, USA.

Peak, S.D. 2001. Development of a bioenergetic growth model to determine the effect of feed allocation program on male broiler breeder growth and performance. Ph.D. Dissertation, The Graduate School, North Carolina State University, Raleigh, NC, USA.

Romero-Sanchez, H., P.W. Plumstead and J. Brake. 2007a. Feeding broiler breeder males. 1. Effect of feeding program and dietary crude protein during rearing on BW and fertility of broiler breeder males. Poult. Sci. 86:168-174.

Romero-Sanchez, H., P.W. Plumstead, N. Leksrisompong and J. Brake. 2007b. Feeding broiler breeder males. 2. Effect of cumulative rearing nutrition on body weight, shank length, comb height and fertility. Poult. Sci. 86:175-181.

Romero-Sanchez, H., P.W. Plumstead and J. Brake. 2007c. Feeding broiler breeder males. 3. Effect of feed allocation program from 16 to 26 wk and subsequent feed increments during the production period on body weight and fertility. Poult. Sci. 86: (in press).

Walsh, T.J. 1996. The effects of nutrition and feed program on reproductive performance and fertility of broiler breeders. Ph.D. Dissertation, The Graduate School, North Carolina State University, Raleigh, NC, USA.

Walsh, T.J. and J. Brake. 1997. The effect of nutrient intake during rearing of broiler breeder females on subsequent fertility. Poult. Sci. 76:297-305.

Walsh, T.J. and J. Brake. 1999. Effects of feeding program and CP intake during rearing on fertility of broiler breeder females. Poult. Sci. 78: 827-832.