The pig farmer generally evaluates the rearing efficiency of the sow in two aspects on the one hand, on the one hand, it evaluates the expression of the production efficiency of the sow (individual); on the other hand, it evaluates the expression of the production efficiency of the sow (herd).
The factors that should be concerned about the reproductive performance of the sow herd are: the proportion of sows in production, the distribution of parity in the production of sows, the success rate of mating in sows, and the average return days of sows in weaned sows (single ) The expression of production efficiency should be concerned with: the number of births per litter of sows and the birth weight of the litters, the suckling capacity of the sows, the weaning weight of the litters, the number of litters per year of the litters, and the initial allocation date of the sows. Age, number of breeding sows that maintain high productivity.
The factors affecting the number of breeding fetuses that maintain the ability of a sow to maintain high production traits are obviously a consequential influencing factor. The probable cause is that the sow may affect the sow's reproductive performance subsequently because of illness, and may also be due to the sow's rearing and management. Improperly and subsequently affecting the reproductive performance of sows, because the nature of this effect may be irreversible, sow reproductive performance can not be restored due to improved nutrition or management, making the long-term impact on sow reproductive performance Sexually, it will cause serious economic losses to the farmer.
At the same time, when pig farm owners evaluate the total economic benefits of individual sows, it is easy to overlook “long-term effects†because feeders are vulnerable to “immediate effectsâ€. Researchers in the pig industry may also struggle to organize and persist in long-term observations because of the sow’s scientific research. The relevant conclusions need statistical support from the historical data of sow reproductive efficiency. It is also difficult to draw attention. Because of this, factors that affect the subsequent reproductive performance of sows should cause more concern in the industry.
Feeding and management of gilts affects subsequent or lifetime reproductive performance of sows
Pig farm owners and researchers learned from the Swine Science Conference held in New Zealand in 2006 that the notion that gilts had to wait until the second estrus to breed was out of date. The experimental data provided in the conference published papers indicate that there is no significant difference in the number of first and second ovulation and implanted embryos of gilts after receiving boar stimulation.
Prof. Paul Hughes of Australia also pointed out: When should breeding gilts for the 21st century? The traditional approach is that most pig farmers are bred during the second or third estrus of the gilts. The purpose of this is to attempt to obtain a higher number of sows at the first sow because we believe that the lower number of ovulation during the first estrus of sows limits the increase in the number of first births. Their recent research shows that whether or not modern sows have the same number of ovulations after their first estrus as they did 20 years ago, in general, when the number of ovulations of sows reaches 13 to 14, it will not happen. There is a limiting effect on the number of births. And more importantly, studies have shown that the number of ovulation does not have much to do with the age of the sow and the number of estrus.
Conclusion: It is feasible that sows are bred for their first estrus.
Practice data further suggests that early maturing gilts are the most fertile sows. Daza et al.'s statistics on the European sow's archives confirm that the total number of live pigs or weaned pigs per sow “declined linearly with age at the time of first delivery, and the youngest young mother at the time of deliveryâ€. The highest value can be obtained for pigs.†Daza et al. also confirmed that “from the first estrus to the first pregnancy and the delay of 1 to 2 personality cycles, the annual productivity of the animals is severely lost.†The average number of litters (followings) decreased as the age of the young sow increased at the time of first delivery.†Daza et al. also pointed out: “The number of weaned sows in early breeding sows is more than the number of late sow sows. Each breeding pig also saves fine material (the same number of tires are eliminated).â€
Therefore, it is necessary to reform the gilt rearing and management to raise awareness of the status of production performance of sows.
It is worth noting that the initial mating age of gilts affects the sow's subsequent reproductive efficiency; early mating sows have higher reproductive efficiency than late mating sows. Several important indicators of sow production efficiency: whether gilts can enter early stage of puberty; how many sows are born in the first sow; whether the number of sows in two sows can increase; whether sows can maintain high productivity. More than 6 births are subject to proper breeding of gilts.
In practice, the difference in the average age over 100 days in the puberty period has been observed in both Chinese and European pigs. Therefore, there is no reason to ignore the difference in reproductive performance of sows due to the difference in the primordial sow's ecstatic period, thus resulting in the difference in economic efficiency of the farm.
Another issue that must be addressed is the relationship between body weight and lifetime reproductive performance of the first parity sow. Throughout the breeding cycle, nutrient consumption is high due to the vigorous activity of all parts of the sow's body. Because the first litter sow weighs less, it needs to support the body's need for rapid estrus again. The first sow's "emotional estrus again" requires some weight support. William and Mullan studied the relationship between weaning weight X (kg) and estrus interval Y (d) in the first litter sow, and suggested that the first weaning sow had a weaning weight of 150 kg or more to shorten the interval between weaning and breeding. Therefore, sows with relatively small body weight at weaning may reach estrus 15 days after weaning. Because young sows have relatively small absolute weight, the consumption of a large number of body proteins and body fats during lactation may cause greater damage.
Therefore, controlling the primordial sow and increasing the weight of the first-born sow are important factors affecting the sow's reproductive performance. This should be used to update strategies for gilt management and nutrition.
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