Egg production
The average egg production percentage differed significantly (P<0.01) among treatments (Table 1). Up to 60
th day of experimental period, irregular trend in production % was observed among different treatment groups, but average production percentage up to 90 days, was found to be the highest in 5% group over other groups control, 10% and 15% respectively. Egg production increases up to 5% level of liquid whey supplementation but increasing the level beyond it again decreased the egg production.
Sathya and Muragian (2015) and
Lokapirnasari et al. (2017) reported that a suitable condition of the digestive tract increases the metabolic process and absorption of necessary nutrients for the body and also helps in increasing production performance in layer birds.
Yang et al., (2018) reported that dietary changes in laying chickens effect egg production and egg quality.
Weight of egg (g)
Average egg weight in all the groups differed significantly (P<0.01) from each other (Table 1). It was observed that as the level of whey supplementation percentage increased, egg weight also increased up to 90 days study period and was found to be the highest in 15% supplemented group. The increased weight in treatment groups might be due to the positive effect of whey supplementation on egg size and weight. This concept is supported by many researchers. In a study, it was found that increase in egg weight and egg mass weight was highly significant (P<0.01) by the administration of fermented whey cheese (P1) compared to the control treatment (P0). Increased egg weight was related to the content of lactic acid bacteria in the digestive tract which might have inhibited pathogenic bacteria that used protein in the small intestine. This finding is in accordance with the findings of
Chaucheyras-Durand and Durand (2009) and
Guclu (2011) reported increase in egg weight by whey protein supplementation in layer birds. According to
Huda et al., (2019), the utilization of lactic acid bacteria, which was applied to animal feed, could inhibit the growth of pathogenic microbes in the small intestine leading to protein absorption and increase in egg weight. Further,
Pradikta et al., (2018) explained that the absorption rate of food substances in the digestive tract would work better with the help of lactic acid bacteria; food substances contained in the feed, such as protein and amino acids, would be better absorbed in the body. This protein and amino acids would be used by chickens to produce eggs. According to
Istinganah et al. (2013), the essential factor to influence egg weight was protein and amino acid content offered as about 50 per cent of the dry matter contained in eggs is protein, therefore amino acids supplements are essential in the process of egg formation. Egg mass and egg weight also appeared to increase after supplementation with prebiotic, probiotic and EO in the diet of layers
(Olgun, 2016). Whey contains high quality protein alpha Lactalbumin and Beta Lactglobulin. These protein plays an important role as better absorption and immunity booster. When supplemented with water to the layer birds, it led to improve egg weight and egg protein due to better absorption and decrease in morbidity and mortality in the whey supplemented birds over control group.
Zia et al., (2016) reported improvement in weight of egg by selenium -yeast supplementation in poultry ration @ 0.3 mg/kg.
Egg quality
Shape index of egg
The higher shape index was observed in the whey supplemented groups and was the lowest in control (Table 2). Although irregular increase was found among treatment groups up to 45
th day of trail but later up to 90
th day of trial there was progressive increase in average shape index of eggs and was found highest in 15% whey supplemented group. This finding is in accordance with the findings of
Bouassi et al., (2021), who reported improvement in shape index of egg by prebiotics and whey supplementation.
Egg shell thickness
The variations were non-significant.
Albumen quality of egg
The average value of Haugh unit observed during 90 days of experimental period which varied from 75.0 to 93.66 (Table 2). On first day of study, although treatment groups showed higher and significantly different (P<0.05) average value than control but the treatment groups didn’t differ significantly (P<0.05) among themselves. On 15
th day of study, numerically higher average value was observed in 15% group followed by 10%, 5% and control group. But the differences were non-significant. On 30
th and 45
th day of study, it followed the same trend as first day of study. On 60
th, to 90
th day of study, significantly different (P<0.01) average value was observed in treatment groups than control but the treatment groups didn’t differ significantly among themselves. The lowest value for Haugh unit was found in Control and highest value was observed in 10% among all treatment groups up to 30
th day of experiment. After that up to 90
th day highest value was observed in 15% and lowest in control. All treated samples differed significantly (P<0.01) from control but didn’t differ significantly among themselves. Higher the value of Haugh unit better is the egg albumen quality. In this experiment, egg quality improved upon supplementation of whey up to a level of 15 per cent up to 90 days of experiment.
Yolk quality of egg
The average value for yolk index was found to be varied from 0.29 to 0.44 in different treatment groups from first to 90
th day of study period (Table 2). On 1
st day of experiment, highest value was observed at 5% level and rest other treatment groups showed same value. On 15
th day highest value was observed at 10% level but after that highest value was observed in 15% group and lowest in control group. On 90
th day, 5% level gr showed similarity with other treatment groups, but 10% and 15% level group didn’t differ significantly from each other. Although yolk index was numerically higher in 15% supplemented group and lowest in control group, however on first, 30
th, 45
th and 75
th day, the differences were non-significant among all treatment groups. This present study shows similarity with the findings of
Youssef et al. (2013), who reported improvement in egg quality by prebiotics and organic acids treatment.