Assessing the performance response of laying hens to intake levels of digestible balanced protein from 27 to 66 wk of age

Abstract

Laying hens continue to improve in egg production (EP) and feed efficiency (FE), and therefore, it is relevant to re-examine their digestible balanced protein (BP) requirements. From 27 to 66 wk of age, hens (Lohmann-LSL Lite) were fed diets designed to provide 550, 625, 700, 775, or 850 mg hen −1 d −1 of amino acid balanced digestible lysine (Dlys). Response criteria included EP, egg weight (EW), feed intake (FI), mortality, egg mass (EM), egg size classifications, FE (kg feed kg −1 EM), and lysine efficiency (LE; mg Dlys g −1 EM). The experiment was a completely randomized design, and data were analyzed using regression analysis. Differences were considered significant if P ≤ 0.05. Hen-day (HD) EP, EW, EM, FI, and LE increased and FE and mortality decreased in a quadratic fashion with increasing Dlys intake, while the proportion of cracked eggs increased linearly. Egg size classifications increased linearly (jumbo, extra-large) and quadratically (large) or decreased in a quadratic manner (medium, small) with increasing Dlys intake. Maximum HDEP, EW, and EM, and minimum FE were achieved at 769, 903, 836, and 839 mg hen −1 d −1 intake of Dlys, respectively. In conclusion, the digestible BP requirement of laying hens varies with response criteria.

Assessing the response of hen weight, body composition, feather score, egg quality, and level of excreta nitrogen content to digestible balanced protein intake of laying hens

“…Dietary AA have a profound impact on the egg production, EW, and efficiency of feed utilization. In other work from our laboratory, the estimated levels of AA balanced Dlys intake required to maximize HDEP and EW, and minimize feed to egg mass ratio were 769, 903, and 839 mg d −1 , respectively (Kumar et al 2018). These values must be kept in context when considering the results of this research.…”

“…Treatment also did not affect ovary weight, and the number and size of LYF and SWF. Hens fed these diets produced smaller eggs with smaller yolks (Kumar et al 2018), so an effect on follicle weight was anticipated. A lack of adequate replication could be one of the reasons for not seeing a significant effect.…”

“…Among, the more important nutrients are the essential amino acids (AA) required for both maintenance and production characteristics (Bregendahl et al 2008). Other work in this laboratory has examined the effects of balanced digestible AA (Kumar et al 2018) on primary egg production and feed efficiency. The current work will report on the response of other relevant laying hen characteristics including HW and body composition, feathering, aspects of egg quality, and the nitrogen (N) content of hen excreta.…”

Dietary Inositol Reduces Fearfulness and Avoidance in Laying Hens

“…Diet composition and analyses are presented in Table 1. Two diets were formulated to either meet the requirements (840 mg/h/d D-Lys; [25]; high balanced protein—HBP) or to have a reduced level (80% of HBP diet) of balanced protein (672 mg/h/d D-Lys; reduced balanced protein—RBP). To study the effect of phytase and inositol on laying hen behaviour, the HBP diet was divided into two fractions and inositol was added to one of them, creating two treatments: HBP and HBP-Inositol (HBP-I).…”

“…e.g., [23]), measuring feather pecking, fearfulness, and aggression can be more difficult. Diets can be manipulated to facilitate the measurement of treatment effects in the mentioned variables by decreasing dietary crude protein to increase the incidence of negative behaviors such as feather pecking [24,25]. Thus, the objective of this trial was to determine if dietary inositol or inositol derived from high levels of phytase (3000 FTU/kg) action affected the behaviour of hens fed amino acid-deficient and -sufficient diets.…”