Nutrition and metabolism in poultry: role of lipids in early diet

Abstract

Modern strains of broiler chickens are selected for fast growth and are marketed anywhere from 36 to 49 days after a 21-day incubational period. For a viable healthy chick, all the necessary nutrients required for growth and development must be provided by the hen through the fertilized egg. The current feeding strategies for improved growth, health and productivity are targeted towards chicks after hatching. Considering the fact that developing chick embryo spends over 30 % of its total life span inside the hatching egg relying on nutrients deposited by the breeder hen, investigations on nutritional needs during pre-hatch period will improve embryonic health, hatchability and chick viability. In this context, investigations on hatching egg lipid quality is of utmost importance because, during incubation, egg fat is the major source of energy and sole source of essential omega-6 (n-6) and omega-3 (n-3) fatty acids to the chick embryo. Due to the unique roles of n-3 and n-6 fatty acids in growth, immune health, and development of central nervous system, this review will focus on the role of early exposure to essential fatty acids through maternal diet and hatching egg and its impact on progeny in meat-type broiler chickens.

Keywords: Chick; Docosahexaenoic acid; Early diet; Egg; Eicosanoid; Embryo; Essential fatty acids.

Fig. 1

Pattern of total lipid, triacylglycerol and phospholipid transfer from hatching egg to the chick embryo during incubation*. TL = Total lipid, TAG = Triacylglycerol, PL = Phospholipid, E = embryonic age. *The weight of different lipid components in yolk or in remnant yolk sac (g) from day one of incubation through hatching period. n = 8

Fig. 2

Total omega-3 fatty acids in the tissues or cells of chicks hatched from hens fed omega-6 (Control) or omega-3 enriched (High n-3) diet.**Control and High n-3 represent maternal diet supplemented with 3.5 % sunflower oil or 3.5 % fish oil. Both diets were isonitrogenous (16 % crude protein) and isocaloric (2,866 kcal metabolizable energy). Total omeg-3 fatty acids include 18:3 n-3, 20:5 n-3, 22:5 n-3 and 22:6 n-3

Fig. 3

Brain docosahexaenoic (DHA) and arachidonic acid content of chicks hatched from hens fed a different lipid sources*. See Table 1 Foot note for details on diet composition

Fig. 4

Post-hatch changes in the docosahexaenoic acid (DHA) in the brain tissue of broiler chickens. The chicks hatched from eggs depleted of DHA and were fed either flax oil or fish oil after hatch.**The breeder hen diets provided 16.0 % CP, 3.6 % calcium and 2,728 kcal metabolizable energy/kg. Sunflower oil (3.5 %) was used in breeder hen diet to produce DHA-depleted eggs and chicks. Flax oil or fish oil was included in broiler chick diet at 3.5 % and tocopherol content of the diet was 48.3 μg/g