Regulation of intake behavior and feed intake in pigs
Feeding is one of the most basic activities for animals to survive, and is also the primary link in the digestion and metabolism of livestock and poultry. Food nutrition and water are constantly consumed in the body to meet the needs of animal metabolism and drive animals to show feeding behavior. Feed intake of animals includes a series of processes such as foraging, recognition, location perception, feeding, chewing and swallowing. Feed intake is closely related to animal production performance, and has a great impact on animal growth, reproduction and lactation. Therefore, it is of great significance to regulate animal feeding behavior and quantity.
1. Pig's feeding behavior
The feeding behavior of pigs includes ingestion and drinking.
1. Heredity: Arching soil foraging is the main feature. Pig nose is highly developed, and it is used to forage food and smell. Even with modern feeding and feeding a good balanced diet, the pig still has the characteristics of foraging on the arch: when feeding, the force chart occupies a favorable position, and sometimes the forelimb steps into the trough to feed the feed to the ground. Pigs feed on competitive, snatch and feed pigs. They eat more, eat faster and grow faster than single fed pigs.
2, taste: pigs are fond of sweet food. Including non-lactating piglets, they have a sweet tooth.
3. Material type: granular material and powder ratio, pig likes pellet material; dry material and wet material ratio, pig likes wet food, and takes less time.
4, feeding: under natural conditions, pigs feed 6-8 times during the day and feed 3-5 times at night. Each feeding lasted for about 10-20 minutes, and the time limit was less than 10 minutes. Daily and night sucking times of piglets vary with age, ranging from 15 to 25 times. The feed intake and feeding frequency of large pigs increased with body weight.
5, drinking water: common drinking water and food intake at the same time, the pig's drinking water is very large, when eating dry materials, the amount of water is two times the dry material. Drinking water from adult pigs is closely related to ambient temperature. After eating dry ingredients, it is necessary to drink water immediately, about 9-10 times / day. It takes 2 to 3 times to eat wet food. Feeding and drinking water alternately take place when feeding freely, while drinking water only after finishing food when limiting food. Piglets before 2 months of age can generally learn to use automatic water dispensers.
II. Regulation and Control of Feed Intake
The intake of animals usually refers to the weight of animal feed in 24 hours. The weight of feed is kg and% weight. The expected feed intake (DM% body weight) of pigs is 4-5%.
Feed intake directly determines the amount of nutrients that animals can obtain from the environment. It is the basis of evaluating animal nutrient demand and energy metabolism. Feed intake regulation is of great significance to improve animal production effect and feed conversion rate, resist stress and disease, and raise breeding livestock, pregnant, lactating female livestock and commercial pork pigs.
1. Stages in which food intake needs to be increased
1) studies on early weaned piglets in recent decades have shown that daily feed intake of livestock is the main factor determining the growth rate of livestock, especially the daily feed intake of young pigs and suckling pigs, which affects the whole growth process of livestock. During the weaning period, the intake of piglets decreased significantly. Therefore, improving palatability of feed, especially the palatability of suckling pigs and young pigs, is very important to increase their daily intake.
Lack of nutrition in early lactation can have a lasting effect on reproductive performance of sows after weaning. Restricting feed intake at any stage of lactation reduces ovulation and increases weaning intervals. However, in the last week of lactation, the survival rate of embryos in the restricted sows fed freely was higher than that in the sows fed only in the last week of lactation.
3) in a period of stress (e.g. heat stress)
4) 20-50kg growing pigs
At this stage, energy uptake should be maximized. When lysine/energy ratio is appropriate, the deposition rate and energy increase linearly until the appetite limit is reached. Give full play to this potential, not only to ensure rapid growth, but also will not cause excessive fat deposition, or improve the feed-meat ratio.
2. Regulation mechanism of feed intake
Feeding is an animal's nature. Feeding intake is regulated by CNS, and hypothalamus is the center of feeding behavior. The lateral area of the hypothalamus is the central part of stimulating feeding, which causes animals to eat and forage after stimulation, so it is called the hungry feeding center. The ventromedial hypothalamic nucleus (VMH) is the central part of the hypothalamus that inhibits feeding. Animals refuse to eat after being stimulated. Animals with deficiency in this area have overfeeding, so it is called the satiety center. The hungry center was in a state of continuous activity and stopped after being restrained by the satiety center.
The methods of regulating intake include chemical regulation and physical regulation. Chemical regulation regulates food intake by regulating glucose, volatile fatty acids, amino acids, mineral elements, free fatty acids, osmotic pressure, pH value, hormones and so on, while physical regulation is regulated by gastrointestinal tension and temperature changes in the body.
Pigs are mainly chemically regulated. Pig is a typical glutton, and the phenomenon of overeating is the most serious. The response to energy balance and fat balance is not as sensitive as poultry and other animals.
3. Ways to regulate food intake
1) Stimulate the feeding center and increase the intake.
It mainly uses some drugs. Barbiturates are known to affect animal feeding. Injection of 6.5mg pentobarbital into the hypothalamic lateral area of hungry pigs can inhibit food intake. On the contrary, if injected into the ventromedial area, the pigs will be stimulated to feed.
2) Reduce gastric reflex and increase food intake
The feed volume is determined by the structural carbohydrates in the feed and the air and water gap in the feed. In production, feed should be adjusted through proper processing of feed.