INFLUENCE OF SUPPLEMENTAL, DIATARY LACTOSE ON LAYING HENS PERFORMANCE AND SOME INTESTINAL MICROFLORA.

Abstract

The current study aimed to investigate the effect of feeding different graded levels of dietary lactose on performance of laying hens, some intestinal microflora, some blood constituents and egg quality. For this purpose 75 Hy line (W-36) white layers were sited from 70 to 79 week of age in individual cages and randomly distributed into five experimental groups of 15 layers each, the five experimental groups were fed on a basal diet (control) supplemented with four graded levels of lactose as 1%, 1.5%, 2% and 2.5%. The results indicated that, egg production of layers fed 1% and 1.5% lactose were significantly higher by 5.6% and 6.2% respectively than the control group. Average egg weight was not affected by adding lactose into diets. Feed consumption values didn't differ significantly. There were a non significant improvement in feed conversion ratio (g. feed/g. egg) due to enriching lactose into the diets by 1% and 1.5%. The improvement effect of adding lactose on egg production and feed conversion may be related to its lowering pH value of small intestine and enhancing absorption rate of nutrients. Eggshell percentage and eggshell thickness were enhanced due to adding lactose into diets. Blood total protein and albumin values were lower than control while blood globulin was not affected by treatments. Blood total lipids increased by feeding lactose while blood cholesterol wasn't affected. The microbiological examination revealed an increase in lactobacilli sp. and inhibition in count of salmonella due to adding lactose into the diets. E. coli bacterial count was slightly inhibited by the levels of 1%, 1.5% and 2% lactose while the high level of lactose (2.5%) had no effect. The results of intestinal microflora showed that lactose probably offer protection against salmonella by promoting, the growth of lactobacilli bacteria which compete with salmonella for colnisities.