Achieving and Maintaining Fertility in Broiler Breeders
Infertility: Male or Female Problem?
- It could be both.
- However, if an egg is laid, the "potential" fertility is always there.
- Males, may be or may become "impotent".
Causes of Infertility:
- In females mostly due to over-feeding and obesity.
- In males mostly due to over-feeding and under-feeding.
- If a hen produces an egg, infertility may be due simply to absence of semen in oviduct.
- Infectious diseases in Broiler Breeder i.e. Viral and Bacterial.
- Sperm concentration, viability & motility is highest at maturity & up to 45 to 50 wks of age which may start declining after 52 to 55 wks.
- Depends upon feed & season.
- The seasonal decline in fertility has been attributed to the inability of the hens to store adequate number of sperms in the SST (sperm storage tubules).
- Watery (quality) & contaminated semen.
- If quality of spermatozoa deteriorated.
- Less no. of spermatozoa inseminated (Approximately 100 million sperms per insemination are recommended to obtain optimum fertility).
- Improper technique of insemination.
- More time for insemination in hot (summer) period.
- Improper care of semen in summer during A.I.
- Thermal shock during insemination & condition under which semen is held in vitro.
- Not properly use sterilized equipments for AI.
This in turn may be due to:
Mating frequency or mating success.
That’s why males are more critical but often overlooked.
A fertile egg
- Must have gone through a fusion of male and female gametes.
- Must have a properly developed embryo at oviposition.
Fertilization: When / How It Happens?
Sperm : Egg interaction:
- After copulation, small % of spermatozoa enters the sperm storage tubules (utero-vaginal junction).
- Spermatozoa are released around 30% per day, to the infundibulum during 10 minutes around ovulation.
- During the 10 minutes ovum moves down and secretions involve it, preventing any more sperms to attach.
- Only the pronucleus of one spermatozoa is allowed to fuse with the female gamete at the center of germinal disc (4 – 5 hours).
- Number of holes in perivitelline membrane is important.
- A total of approx. 1000 around ova with 6 holes around the germinal disc.
- Surprisingly, this process is incredibly efficient.
- Under most conditions fertility level reaches over 90%.
- However, the % of infertile eggs can be of significant economic importance.
- Highest fertility is the result of good rearing and adult period management of males and females.
Perivitelline Membrane (IPVL) Penetration:
- Spermatozoa "tunnel" into the germinal disc area using proteolytic enzymes. Then, oviductal secretion form the OPVL to prevent to excess sperm activity in the area.
- Fertilization depends on good quality semen (sperm count, motility). Supplied by a well developed male with optimum testicular growth (puberty, early adulthood).
Photo : IPVL technique shows number of spermatozoa that penetrate ova, only ONE reaches gamete fusion.
Hatch and Fertility:
- 85 – 90 % Good
- 82 – 84 % Average
- 79 – 81 % Poor
- At day old, males are smaller and less uniform than females. Smaller egg size.
- They have been detoed, sometimes partially dubbed lead to more stress.
- First feed ingesta: critical to early intestinal development… long term consequences
- Use of light.
Males: Growth Pattern Strategies
Low B.W. target (breeder recommendations) is ideal. However, uniformity is critical.
Used when equipment and density are optimum.
Slightly Higher B.W. target (one week advance) may give better uniformity, longer legs, and good keels.
The Indicator is Uniformity: > 90% at all times.
Rearing the Males:
Male: Beak Trimming:
1. 10 – 11 days: touching
2. 12 – 13 weeks: Debeaking
3. 18 weeks: checking – critical for good mating balance for fertility
Objective: Optimize uniformity
1. At 4 – 6 weeks – good skeletal development
2. At 6 weeks – to monitor / adjust growth pattern.
3. At 12 weeks – to monitor / adjust growth pattern
4. At 18 weeks – to transfer/housing and mate the best: fleshing, legs, toes, beak, general conformation.
MALES GROWING PERIOD:
Weight control targets:
Criteria In Males:
1. Monitoring Body Weight
2. Body condition
3. Controlling frame size
Male Sexual Development:
1. Pre-puberty: 13-14 weeks. Slow testicular growth, critical Sertoli cells multiplication and optimum sperm count depends on Sertoli cells determined at this age.
2. Puberty: 13-14 weeks to 24 weeks approx. Rapid testicular growth and semen production begins.
3. Adult Phase: 25 weeks onwards. Testicular growth completed by 30 weeks and remains same up to 40 weeks, then begins to shrink gradually
HIGH YIELD MALES:
Requires long legs, bones and tendons, strong / straight toes, lean breast.
Male Body Weight:
Fertility and Weight Gain:
If 21 – 29 week growth not achieved then no persistency of fertility. Occurs with both over or under weight males.
Male Weight Gain:
"Window of Opportunity"
This period is critical that may determine good or bad persistency of fertility in males may have access to female feed so that B.W. out of control.
Weekly body weight gain 110 – 135 g
Weighing / handling weekly
Maintenance represents largest feed need
For each kg of body mass needs 35 gm feed for maintenance and a 3 kg male needs
3 x 35 = 105 g for maintenance (@ 25°C)
How much feed?
Total feed need for 3 kg male @ 25°C growing at 13 g/day and feed diet with 2650 kcal/kg
Maintenance 105 g
Growth 30 g
Total 135 g
Feeding Males (35-68 weeks):
1. Slow growth, majority of feed is for maintenance.
2. If males are overweight 200-400 g reduce feed intake by 2 to 3 g/bird/day.
3. If males are overweight > 500 g, use low nutrient density diet.
Males Breast Fleshing:
24 – 27 weeks:
a) 10 – 15 % Slight "U" shape
b) 10 – 15 % Slight "Y" shape
c) 70 – 80 % "V" shape
Males Breast Fleshing:
32 – 40 weeks
a) 10 – 15 % "U" shape
b) 10 – 15 % "V" shape
c) 70 – 80 % slight "U" shape
Above 52 weeks – Majority "U" shape
Male – Female Ratio: