Sulfur amino acid requirements for pullets in growth and pre-laying trials

Abstract

Context To obtain a good performance of the hens in the laying phase, adequate nutrition in the growth and pre-laying phase is necessary, especially for meeting amino acid requirements that are related to development of reproductive organs (ovary and oviduct). Aims The objective of the present study was to predict the requirements for methionine (Met) plus cystine (Cys) from the growth of the body, feathers and reproductive organs of laying hens. Methods The model estimates Met+Cys requirements as the relationship between the deposition of Met+Cys into three compartments (body, feathers, and reproductive organs) and their utilisation efficiency. The efficiency of utilisation was determined by a linear regression between Met+Cys deposition and intake for pullets aged 14–28, 56–70 and 98–112 days. Protein weight and deposition in the body and feathers were determined by the comparative slaughter method. The Gompertz function was used to model body, feathers, ovary, oviduct and liver weight against age. Key results Our results showed that the inclusion of parameters descriptive of the growth of reproductive organs and the correction for feather losses in the model enabled Met+Cys requirements for growth in pre-laying trials to be predicted with a greater precision. Conclusions The model developed in this study for determining the Met+Cys requirements for Dekalb White pullets could be extended, provided the necessary adjustments are made, to other amino acids, strains and species. Implications Meeting Met+Cys requirements in the phase of maximum growth of the reproductive organs (weeks) contributes to the uniformity of the age when the pullets reach sexual maturity and, consequently, start the egg production.

Dynamics of Growth and Egg Traits in Three Dietary Balanced Protein Scenarios Applied for Laying Hens

“…The body fat and egg components are influenced by the feed offered [ 3 ] and eggshell quality reduces as egg weight increases, which may be partially controlled with nutritional strategies [ 4 , 5 ]. In addition, the feed offered to hens during the rearing phase may affect the development of reproductive organs [ 6 ], influencing the long-term laying cycle.…”

“…Therefore, a change in voluntary feed intake is the only mechanism that a hen can use to consume a proper amount of all nutrients. If they fail to do so, body and egg components are expected to change [ 6 , 19 ] along with the egg production [ 20 ]. This highlights the importance to elucidate the dynamics of body and egg composition over different sets of nutrition scenarios.…”

Response of Laying Hens to Repletion and Depletion in Dietary Balanced Protein

“…The growing period of a laying hen is the most critical time in a hen’s life and the mistakes made during this period are difficult to rectify [ 1 ]. Many factors, e.g., quantitative or qualitative feed restriction [ 2 , 3 ], feed program [ 4 , 5 ], and nutritional imbalance [ 4 , 6 ], in the starter, grower, and/or developer phases were reported to affect the growth curve, early egg weight, and sexual maturity of pullets and, consequently, egg production. Therefore, the maximum genetic potential can only be achieved when the bird is provided with all its nutritional requirements [ 7 , 8 ], especially when the objective is to extend the productive life of laying hens.…”