The Role of Protein Reserves in Egg Formation in Birds

Selman, Richard George (1994) The Role of Protein Reserves in Egg Formation in Birds. PhD thesis, University of Glasgow.

Abstract

A technique was developed to estimate the muscle condition of live zebra finches by modelling the profile of the pectoral muscles over the sternum. The relationship between muscle condition, before and after laying, the timing of breeding, and the number and mass of eggs produced was examined. Females lost protein during egg production, but daily seed intake was reduced at this time. This was lower for large clutches than for small clutches. This suggests a reliance on body reserves for the nutrients required in laying a clutch of eggs. No aspect of egg production could be related simply to the amount of protein lost by females during egg formation, but the timing of breeding was related to body condition. This must be the result of variation in the fat reserves of females. The effects of both protein reserve size and quality were therefore compared during egg production. Birds with a reserve of 'high quality protein' laid heavier eggs and larger clutches than those with one of 'low quality protein'. There was a positive relationship between the loss of protein from the pectoral muscles and the clutch size produced by 'high quality protein' birds. These produced large clutches and large eggs. 'Low quality protein' birds all lost large amounts of protein, but laid only small clutches and small eggs. Dissection of the eggs revealed no differences in the relative sizes of egg components with varying egg mass, but shell dry mass was lower for 'low quality protein' birds than 'high'. Very small eggs, produced only by 'low quality reserve' females, did not develop. Amongst the other eggs the probability of hatching was related to egg mass. Hatching size was related to egg mass, but not hatchling condition. The correlation between egg mass and chick size remained through to fledging for chicks reared by birds with a 'high quality protein' reserve. Egg production was therefore greatly affected by the quality as well as the size of female protein reserves.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: David Houston
• Keywords: Zoology, Physiology, Developmental biology
• Date of Award: 1994
• Depositing User: Enlighten Team
• Unique ID: glathesis:1994-74649
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 27 Sep 2019 17:22
• Last Modified: 27 Sep 2019 17:22
• URI: https://theses.gla.ac.uk/id/eprint/74649