In-ovo feeding is one of new innovative technique developed for injecting the nutrients in liquid form into amniotic sac of hatching embryo. This mechanism proves to be important for chick growth as energy and protein are first obtained from yolk and after a span of two weeks derived from albumin. Exogenous material via in-ovo technique was first administered in 1980 for Marek’s disease vaccine .  Furthermore, Ferket et al., (2013) introduced concept of in-ovo inoculation of high volume nutrients in amniotic fluid of chickens and turkeys eggs for feeding embryo.

Thet importance of in-ovo feeding comes in consideration when chicks are fasted for two to three days. This will lead to better growth performance higher immune response and developed immune system of birds. Good health of newly hatched chicks largely depends upon its embryonic life and includes metabolic and physiological transmission of exogenous nutrients to eggs up to five percent chicks are under stress during post hatch period and do not survive due to available limited nutrients. Although egg yolk and albumin contain essential nutrients which are required embryo during incubation, but a large proportion of these proteins constitutes of immunoglobulins, generated during egg production. Fasting period during post hatch results in mobilization of proteins as an energy source, thus it has led to study egg supplementation with various critical nutrients for better growth performance, gut health development, improved immune system. In-ovo feeding minimizes cost of production of feed by directly supplying specific nutrients necessary for growth of embryos. In-ovo technology may also facilitate absorption of specific nutrients by supplying precise nutrition at a specific time. Moreover, the in-ovo technology causes reduction in initial broiler rearing and also improves hatchability.

The digestion and absorption of nutrients before hatch

Embryo of poultry and newly hatched chicks depend upon fat, protein, carbohydrates, water, minerals and vitamins absorbed from various parts of egg like albumen, yolk and shell. There are two routes for digestion and absorption of nutrients for embryonic development. First absorption takes place by yolk sac into blood mainly by yolk sac membrane. Very low density lipoproteins are absorbed by yolk sac membranes cells through process of endocytosis. Digestion of nutrients by yolk sac membrane is quite similar as in small intestine due to presence of most of digestive enzymes. Morphological and digestive changes in yolk sac membrane decide fate of yolk utilization by the chick.  These changes could be consequence of increased nutrient demand from yolk and imbibing of yolk sac in the embryo prior to hatch.

Second route of nutrient absorption is by consuming yolk nutrients from yolk into the intestine. Absorption of nutrients from yolk sac to small intestine enters through yolk stalk by peristaltic movements. Minerals vitamins glycogen fat and proteins are digested by pancreatic enzymes and absorbed by small intestine of chick.

Chick embryo could digest and absorb nutrients before hatching. Gut development occurs throughout incubation period, but proper functioning of gut begins at an age of 17 days of incubation. During this phase of embryonic growth embryo begins to consume amniotic fluid. Intestinal weight at hatch increases to 3.5%. Intestinal brush border enzymes along with key nutrient transporting channels like sodium-glucose pump, ATPase observed at 15 days of incubation began to increase at day 19.  Hatching day shows further increment in their activity along with RNA expression .

Height of the intestinal villi increase by 200-300% from day during last three days of incubation process. There is also increase in intestinal weight. Increase in cell size and cell numbers leads to rapid intestinal development. Enterocyte proliferation is maximized, synthesis of intestinal crypts becomes rapid thus leading to effective and earlier absorption of vitamins minerals and other nutrients necessary for support and development of skeleton and immune system of chicks.

In-ovo feeding at the hatchery

In-ovo injection of Marek’s vaccine was proven effective for Marek’s disease by Sharma & Burmester  (1982). High volume at dose rate of (0.4 to 1.2 ml) were injected by in-ovo method into amnion fluid of growing chick and turkey embryo. Study was designed to check the effects by feeding via in-ovo technique on growth parameters, intestinal and bone health of chicks .

Expected outcomes of in-ovo feeding are a reduction in morbidity and mortality rates after hatching. Nutrient utilization is enhanced, and the enteric immune system is improved. Skeletal disorders are minimized thus leading to higher breast meat yield together with improved muscle development.

A linear reduction in chick weight from 0.14 to 0.17 g at hatch occurs because of late access to both feed and water. Chicks held at the hatchery without feed and water lost 6 -9 g weight.

NUTRIENTS for in-ovo feeding

A variety of nutrients can be inoculated via in Ovo route. Glucose sources of energy can be fulfilled through in-ovo feeding of several carbohydrates. Sodium chloride ions play a prime role in the absorption of glucose and amino acids through the activation of apical and basolateral transporters. Another important nutrient for in-ovo feeding is the metabolic product of leucine known as β-hydroxy-β-methyl butyrate (HMB), which promotes muscle growth by activating satellite cells of muscles. Moreover, minerals and vitamins could also be easily used for in-ovo feeding (Nissen et al., 1994; Kornasio et al., 2009).

Most of the nutrients were studied for their impact on hatchability, quality of chick, and growth performance parameters. Among them is ascorbic acid which is stabilized vitamin C (Ipek et al., 2004), amino acids (Bhanja et al., 2004); Vitamins (Bhanja et al., 2007); linoleic acid and glutamine (Pedroso et al., 2006), carbohydrates (Uni & Ferket, 2004), L-Carnitine (Zhai et al., 2008), dextrin & glutamine (Chen et al., 2009), vitamins and minerals (Yair et al., 2013). Effect of feeding via in-ovo route solution of dextrin solution in commercial turkey (Bottje et al., 2010). Studies revealed higher hatch weight, improved hatchability, and rapid early chick growth.

 By studying earlier research conducted by different researchers, it becomes easy to predict that by taking considerations of, exact volume, time of in-ovo inoculation, osmolality and viscosity of different exogenous nutrients different numbers of nutrients or supplements can sufficiently be included via administration of solution via in-ovo technique.

References are available from the Author: Khawaja Yasir Imtiaz (16-arid-5824). info@foodfeedinfo.com