ZOO510 Assignment 2 Spring 2021 – Assignments – Solution VU

ZOO510 Assignment 2 Spring 2021 – Assignments – Solution VU

ZOO510 Assignment 2 Spring 2021

Credit: Muhammad Kashif Murtaza



Factors That Affect Egg Size

All hens cannot produce eggs of the same size, but some factors determine egg size. If you want to control the size of your eggs, you should understand the various factors that affect the size of the eggs. You should also take corresponding measures according to these factors to achieve your purpose.


1. Breed

Type of breed is one of the factors that affect egg size. Some breeds of chickens are known to produce small eggs due to their small body sizes and genetic makeup, while some chicken breeds produce medium to large eggs. So the breed of chickens being raised determines the size of eggs that will be produced or laid.


2. Ambient Temperature

The chickens bred in the hot season usually lay small eggs after the start of production. First, the daily hours of sunlight are increased in the hot season or summer, and this always results in early sexual maturity and early onset of egg production. However, the eggs produced by the chickens are often small.

Secondly, in the hot season or summer, the feed intake or consumption of birds is often low, and their body size is also small. As a result of that, they lay small eggs.

When the temperature of the chicken house exceeds 27oC, the eggs produced by the laying hens are smaller. The higher the ambient temperature, the smaller the egg production and egg size.


3. Lighting Programs

Egg size is influenced by lighting programs adopted in the growing period. Lighting programs can delay or accelerate sexual maturity. The age at which chickens begin to produce and lay eggs has a significant influence on the egg size. The younger the hen, the smaller the eggs produced in the first year of life.

The extension of daily hours of light in the growing period to 11 hours (or more) will accelerate sexual maturity and onset of egg production, and the eggs produced will be very small. The shortening of daily hours of light in the growing period to 10 hours from the 10-18 weeks of age will delay sexual maturity and onset of egg production, but the eggs produced later would be big. Eggs are big when the production starts late.


4. Age of Hen

The younger the laying hens, the smaller the eggs are, and as the laying hens grow older, the eggs gradually increase in size. The eggs produced by old layers (about 1½ – 2 years) are often large and can reach more than 70 grams. Birds at 20 – 26 weeks of age will lay smaller eggs than at 40 – 50 weeks. Maximum egg size can be expected when the birds reach about one year old. Egg size tends to get smaller just before birds stop laying.


5. Feed Intake

Provided that all required nutrients are available in the correct level in the feed, the higher the feed intake, the larger the eggs, and the lower the intake, the smaller the eggs. This is simply because eggs are also derived from feed through digestion, absorption and metabolism.


6. Water Consumption

Water contributes significantly to the size of an egg. When the water consumed by a hen is low or inadequate, it affects the egg size and production. The quality of water is also vital. Avoid serving hot, too cold or dirty water to chickens. It has adverse effects on the production and welfare of chickens. Keep the water fresh and clean, and look out for faulty drinkers (or nipples) and fix them.


7. Body Weight and Physique

Chickens with higher body weights lay larger eggs, and chickens with smaller body weights also lay smaller eggs. The size of body weight is related to variety, availability of required nutrient, light and feed intake. Therefore, the size of the egg can be controlled by controlling the weight and body size.


8. Nutrition

Nutrition is the “raw material” of eggs, and normal-sized eggs can be produced with full-price feed formulated according to the growth and development of chickens and production. The loss or unavailability of one or several nutrients affects the egg production rate and egg size. Research studies [1][2]have revealed that egg weight and size respond to methionine and linoleic acid levels.


9. Diseases

Diseases are stressors to chickens. They affect the feed intake of chickens to varying degrees and directly affect the egg production rate and egg size of chickens. Therefore, prevention and control of diseases is a critical task in production. Proper hygiene and management will reduce the risk of infections. Preventing and controlling diseases is not only to enhance the quality of eggs but also a major element in the success or failure of chicken production.


10. Egg Cooling and Storage Condition

It is important to cool eggs as quickly as possible after they are laid and to store them at a temperature of 50oF to 55oF; otherwise, they will lose weight by evaporation. This may result in poorer grading results, and so a poor economic return.


Question 2: How biosecurity practices prevent the poultry from different diseases? (5)


Biosecurity refers to procedures used to prevent the introduction and spread of disease-causing organisms in poultry flocks. Because of the concentration in size and location of poultry flocks in current commercial production operations and the inherent disease risks associated with this type of production, it is imperative that poultry producers practice daily biosecurity measures.


1)How Micro Organisms Spread

The primary method of spreading disease causing microorganisms between poultry flocks is the use of contaminated equipment or exposure to contaminated clothing and footwear of humans. Infected animals, such as wild birds and rodents, can also be a source of disease for poultry flocks. Disease causing viruses and bacteria can be transported from one flock to another on bird transporting equipment, trucks, tractors and other farm equipment as well as egg flats and cases. Humans and animals are also important ways of transporting disease causing organisms.


2)Keep Visitors to a Minimum

Human transportation of microorganisms is one of the more serious threats to biosecurity. Restriction of unnecessary human traffic is a major component of a sound program. Growers should restrict visitors and make sure that any visitor to their farm has a good reason to be there. Growers should provide protective covering such as boots, coveralls, and headgear to any visitors that work with, or have had recent contact with poultry.. Traffic through poultry houses should always flow from younger to older birds. One useful measure is keeping records of visitors that have been on the farm. If a problem arises, knowing who was there will help in limiting additional flock infections.


3)Limit Visitations to Other Poultry Farms

Poultry growers should refrain from visiting other poultry operations unless absolutely necessary. When-ever it is necessary to visit another farm, growers should be sure to exercise additional precautions such as showering and changing clothes before arriving and washing any vehicle before entering a farm.


4)Keep All Animals Out of Poultry Houses

Animals can be carriers of poultry disease causing organisms. Growers should not allow pets such as dogs, cats or other animals in their houses.


5)Practice Sound Rodent and Pest Control Programs

Rats, mice, and insects such as flies and darkling beetles can carry and spread microorganisms. Growers should consult with their poultry company and practice effective rodent and insect control programs. Eliminating or reducing as many of these pests as possible will reduce the risk of contracting or spreading a disease.


6)Avoid Contact with Non-Commercial Poultry or Wild Birds

Poultry growers should avoid all contact with non-commercial sources of poultry including backyard flocks, fanciers, fairs, poultry shows, and markets. These types of poultry are seldom fully vaccinated for the major poultry diseases and they are often exposed to many types and flocks of birds. Non-commercial birds represent extremely high-risk contacts. Employees should not be allowed to own their own poultry and neighbors with backyard flocks should be informed of the importance of getting sick or unhealthy birds to a diagnostic lab as soon as possible. Growers should also avoid wild birds such as ducks, geese and turkeys.


7)Inspect Flocks Daily

Growers are required by their contract to inspect their flocks every day. Mortality should be picked up daily and disposed of in a timely and approved method. Stock-piling mortality and allowing carcasses to decompose before disposal increases the risk of spreading disease via rodents and insects. Growers should report increases in mortality or signs of health problems to their service representative immediately. This is required by contract and will ensure a rapid detection and response should a disease be present. Growers should check with their poultry company before using any vaccines, medications or drug treatments for a flock health problem. Timely reporting of health issues on a farm will not only help restrict additional infections, but will minimize losses to both the grower and the company.


8)Maximize the Environment

Maintaining litter in a relatively dry condition (i.e. 20%-30%) and providing good ventilation will help control microorganism numbers. Wet conditions combined with warm in-house temperatures provide a good growth environment for most disease causing organisms. Good ventilation also helps reduce microorganisms as fresh air entering and leaving the house dilutes microbe populations and removes them from the house. Poor ventilation can result in irritation of the respiratory tract of birds making them more susceptible to bacterial and viral infections.


9)Keep Areas Around Houses and Feed Bins Clean

Keeping grass and weeds cut around poultry houses and removing used equipment or trash is beneficial in keeping rodent and insect populations under control. Thick grass or weeds and old equipment provide refuge and habitat for rats, mice and insect pests that can spread disease. Spilled feed should be cleaned up regularly and not allowed to collect for long periods of time. Spilled feed around the feed bins will attract birds, rats, mice and insects.


10)Disease Recognizing Symptoms

It is important for poultry growers to be aware of signs of disease in their flocks. Early detection of contagious diseases can greatly reduce the impact and spread of that disease to other flocks. Clinical signs associated with the possibility of a disease in a poultry flock are:

  • Lack of energy and appetite
  • Decreased egg production
  • Soft-shelled eggs or misshapen eggs
  • Swelling of the head, eyes, comb, wattles and hocks
  • Purple discoloration of the wattles, combs and legs
  • Nasal discharge
  • Coughing, wheezing and sneezing
  • Lack of coordination in mobility
  • Diarrhea
  • Sudden or excessive mortality without clinical signs

Contract poultry growers should notify a representative of their poultry company immediately if any symptoms of a disease condition is observed.


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