In a paper presented to the recent International Poultry Science Forum in Atlanta, Georgia, Diego Bohórquez showed that in-ovo feeding can be beneficial and can enhance the poults' morphological development.

Mr Bohórquez told the Forum that in-ovo feeding enhances digestive capacity, feeding behaviour and quality of poults, but he said that little is known about its influence on the morphometrical and ultrastructural development of small intestine epithelium during the perinatal period.

He said that in the two to three hours after hatching, baby chicks can suffer through the breakdown of the villus leading to possible infection.

However, he said that through in-ovo injection by targeting the embryonic fluid, it was possible to boost growth and increase disease resistance.

The experiment took two groups of eggs were injected at 23 days of incubation with either 0.4 ml of a 0.4 per cent saline solution or 0.4ml of an in-ovo feeding solution.

At hatch, 120 poults from each treatment were distributed among 24 cages (10 poults/cage) and reared to 11 days of age. Body weights, cumulative feed conversion ratio (cFCR) and mortality rates were evaluated at one, four and 11 days.

Samples were collected for jejunum histomorphometry (light microscopy) and ultrastructural (electron microscopy) analysis at each time point.

"Jejunum gene expression was surveyed at four days using a focused microarray designed for 320 unique gene sequences selected from the chicken genome," Mr Bohórquez said.

"Also, expression of membrane-bound MUC1 and secretory MUC2 mucin genes was evaluated by real-time PCR at four days and 11 days."

He added that although there were no treatment effects on body weight at hatch, the in-ovo-fed group had 16 per cent more apparent villus surface area than controls.

Electron micrographs revealed they also had more mucus secretion.

"The villi were tight, producing more mucous and they were more healthy," he said.

At four days, in-ovo feeding down-regulated gene expression involved in smooth muscle growth, and up-regulated gene expression of intestinal disaccharidases, epithelial cell growth, thyroid receptors and innate immune response, he said.

Although histomorphometrical differences dissipated with age, in-ovo-fed birds had five per cent higher body weights and six per cent lower feed conversion ratio by day 11 compared to controls.

Mr Bohórquez concluded that in-ovo feeding turkey embryos enhances morphological development and the protective mucus blanket of the small intestinal epithelium, which may improve nutrient utilisation resulting in higher body weight and better feed conversion ration post hatch.

In-Ovo Injection of L-Carnitine

However, another study by researchers at Mississippi State University into the hatchability and grow out performance of broiler chicks following in-ovo injection of L-carnitine - a synthesised animal tissue - showed no influence on embryogenesis, hatchability or broiler chick performance through to day 10 post hatch.

The effects of in-ovo injection of L-carnitine on hatchability and subsequent grow-out performance was tested on 672 Ross x Ross broiler chicks from a young breeder flock.

The fertilised eggs were injected in the amnion with L-carnitine (0.5, 2.0 or 8.0 mg per 100 µl commercial diluent) on day 18 of incubation.

Three control groups (non-injected, and injected with or without diluent) were also included.

The study recorded the hatch time, mortality and hatchability.

Mortality, body weight gain and feed intake were measured at regular intervals up until day 10 after hatching.

The study found there were no treatment effects on embryonic mortality, hatchability, hatch time or relative tissue weights.

However, on the third day after hatching, the 0.5 mg L-carnitine treatment showed a significantly higher moisture content of the pipping muscle when compared to the 8.0 mg treatment and the diluent-injected control group.

M.M. Keralapurath from Mississippi State University said that the addition of L-carnitine to the maternal diet had resulted in higher breast meat yields and improved hatchability, but there was no difference through in-ovo injection because of the differences between the egg-type strain of the product and the meat-type strain.

He said that further research needs to be conducted into yield in broiler chicks and also into administering L-carnitine together with Marek's disease vaccination.