Productivity factors and egg-laying performance indicators of poultry

During the moulting period, poultry does not lay eggs; therefore, the later the moult begins, the more stable and higher the egg productivity. Good laying hens moult late (October–November), while poor laying hens begin to moult early. After the moult ends, egg laying resumes, so the shorter the moulting period, the more eggs are obtained from the bird. Good layers moult over 2–3 weeks, while poor ones take up to two months or more. If feeding and housing rules are violated, egg productivity decreases, and in some birds, it ceases, which may result in untimely moulting. Reasons for moulting in spring or winter may include, for example, a lack of protein feed in the ration, failure to follow lighting schedules, etc. In these cases, measures are taken to restore egg productivity, after which the moult usually ceases.

The intensity of egg productivity is expressed for a group of birds, such as a line, cross, or flock, as the percentage ratio of the number of eggs laid to the number of feed-days over a specific period of time. The intensity of egg productivity for an individual bird can be expressed as a percentage of the number of days in a given period, such as a week, month, or year. For example, the egg productivity intensity of a hen that laid 27 eggs in 30 days would be 90%, and at a breeding farm with a population of 50,000 hens, where 30,000 eggs were collected in one day, it would be 60%.

The biological cycle of egg productivity is defined as the period from its beginning to the next moult. The biological cycle of egg productivity is linked to different hatching times of the birds and can begin and end in different months, being approximately equal to one year. This cycle in ducks, turkeys, and especially in geese is characterized by greater brevity and seasonality. A long biological cycle is characteristic of birds with early sexual maturity and stable, rhythmic egg productivity.

Species differences in egg productivity are very large. Good egg productivity for chickens is 220–250, and potentially 280–300 eggs, for ducks — 180, for turkeys — 100–150, for geese — 80–100 eggs or more per year.

Breed differences in egg productivity are especially noticeable in chickens and ducks. Chickens of egg-laying breeds lay on average 10–12% more eggs than dual-purpose breeds and almost twice as many as meat-type chickens. Approximately the same difference in egg productivity exists between ducks of dual-purpose and meat breeds. All breeds of geese and turkeys belong to the meat production type, so the difference in egg productivity among them is smaller. Within the same production type, breed differences in egg productivity in chickens and ducks are usually less pronounced and depend on breeding work with the breed.

The productivity of egg-laying chicken lines is 220–260 eggs, meat-type lines — 180–200, and hybrid birds — 240–280 eggs or more per year.

A comparison of egg productivity intensity over the biological cycle based on more than 581 productivity curves of various poultry species shows that sexual maturity, stability, and intensity of egg productivity are most pronounced in Leghorn chickens. The egg productivity of these chickens began at 5 months of age at 20%, but by the next month, it reached 60% and was maintained at a level of 60–81% for 11 months; the chickens laid for more than a year. Duck egg productivity began at 7 months of age at 36%, increased to 81% after two months, but the entire egg-laying period was limited to seven months. Turkeys and geese possessed lower sexual maturity and more pronounced seasonality of productivity. Due to differences in sexual maturity, stability, and egg productivity intensity, the productivity of chickens over the biological cycle was 268 eggs, ducks — 109, guinea fowl — 100, turkeys — 89, and geese — 42 eggs. These data are not normative but characterize the biological traits of different poultry species regarding differences in egg productivity. In practice, these differences can vary within certain limits under the influence of breeding work, hybridization, and bird feeding and housing conditions.

Individual differences in egg productivity often exceed breed differences: some individuals and even breeding groups of dual-purpose chicken breeds have higher egg productivity compared to individual chickens and groups of the egg-laying type. Chickens that lay daily throughout the year are found in both egg-laying and dual-purpose breeds selected for high egg productivity.

Table 4. Egg productivity intensity (%) of livestock poultry of different species by month (according to T. A. Zamoiskaya)

Egg productivity by month of life Eggs laid.

Poultry species biological cycle [2 [3415] 6[78| 9 | 10| 11 13 [14 | 15 16 |7 18 (pcs.) Chickens (Leghorn) 20] 60] 78] 81| 78] 75] 72] 69] 67| 66] 62] 60156]50 268

Ducks | Ы[Ь 36] 57| 81| 65! 55] 30] 6 109 Guinea fowl 12] 33] 54] 78| 60] 39] 15] 6 100 Turkeys 171 65 70 6 И4И| 12 89 Geese 13| 38| 39] 2891 2 42

Age-related changes in egg productivity, associated with a gradual decline in reproductive function, are characteristic of all species and breeds of poultry, although to varying degrees.

The egg production of the same hen, duck, turkey, or the flock as a whole decreases with age. In chickens, the annual decline in egg production is 10% or more of the number of eggs laid in the first year of laying. However, in some cases, an increase in egg production is observed in the second year, which may be due to the characteristics of the constitution and the physiological state of the poultry. The best layers have good egg production for a number of years; the total number of eggs obtained from them is high. For instance, at the "Kuchinsky" breeding farm in the Moscow region, hen No. 613 of the Russian White breed laid 189 eggs in the first year of laying, 235 in the second, 214 in the third, 222 in the fourth, 187 in the fifth, and 1047 eggs in her lifetime.

The biological potential for egg production in poultry is maintained for up to approximately ten years; however, the economics of poultry farming dictate stricter frameworks. In breeding farms, chickens, ducks, and turkeys are kept for no longer than two to three years, and on commercial industrial farms, the livestock is replaced annually. An exception is geese: their egg production increases gradually, reaches a peak in the second to third year of life, and only then declines.

• Maximum egg production — about 10 years
• Use in breeding farms — 2–3 years
• Replacement of the flock on industrial farms — annually
• Increase in productivity under intensive technology — from 160–179 to 230–260 eggs per year

Egg production is a heritable trait passed on to offspring from both the maternal and paternal sides. Moreover, the genetic influence of the father is more significant, although the trait itself is characterized by a low heritability coefficient. Systematic breeding work, the development of productive lines, and their subsequent industrial crossbreeding allow for the improvement of economic indicators.

Microclimate management and elimination of seasonality

In the natural environment, the productivity of poultry is strongly influenced by the seasonality of external conditions. In the Northern Hemisphere, egg-laying traditionally begins in the spring and ends in the summer. In the Southern Hemisphere, a similar peak is observed in the spring months from September to November, while in tropical regions, seasonal fluctuations are almost absent.

Artificial regulation of the microclimate and feeding helps to smooth out seasonal declines and level the egg-laying schedule. With the growth of total annual egg production, the intensity of seasonality decreases. Under these conditions, the best economic effect is achieved by combining scientifically sound care and the use of high-productivity hybrid poultry.

Rhythmic egg production with year-round flock replenishment of caged layers significantly increases productivity. Under intensive farming conditions, the egg production of chickens increases from 160–179 to 230–260 eggs per year, with a simultaneous increase in the number of livestock. Such a result is achieved through the implementation of a complex of measures:

• use of highly productive breeding and hybrid poultry;
• application of scientifically sound, standardized feeding;
• creation and maintenance of a regulated microclimate;
• automation and mechanization of production processes;
• strict adherence to the system of veterinary and preventive measures.