Yorkshire or Yorkshire, also known as Yorkshire pig or Yorkshire pig, originated in Britain. The main features are long head, slightly concave face, medium-sized ears, lean forward and stand slightly, wide and slightly arched back, white coat, strong limbs and good meat posture. Adult boars and sows weigh 300-450kg and 200-350kg respectively. Under good feeding conditions, the body weight can reach 90kg at the age of 6 months, and the daily gain is more than 750g at the stage of 20 ~ 90 kg, and the feed-to-weight ratio is 3 ∶1; The slaughter rate is 72%, and the lean meat rate is 60% ~ 65%.

Fig. 3 Yorkshire pig Yorkshire pig has late sexual maturity and strong reproductive ability, and the litter size is 1 1. With thin back, more lean meat, excellent meat quality and strong physique, it is an excellent pig breed with wide distribution and the largest number in contemporary times. Commercial lean pigs were produced by binary or ternary hybridization of many local pig breeds in China, and the hybridization effect was obvious.

Landrace, also known as Landrace, is native to Denmark. This kind of pig has a long body and flat and streamlined lines on its back and abdomen. Handsome head and neck, straight face, drooping ears, muscular hips and thighs; The whole body is white with hair. Adult boars and sows weigh 250-300 kg and150-200 kg respectively. At the weight stage of 30 ~ 100 kg, the average daily gain was 933g, the feed-to-weight ratio was 2.63∶ 1, and the carcass lean meat rate was 64.4%. High fertility, the litter size of multiparous sows is 10.

Figure 4 Landers Pig This breed has played an important role in the improvement of pig breeds and the production of commercial pigs in China, but it requires higher feed conditions and has a slightly poor cold tolerance.

Duroc, originally from the United States, is a lean pig breed improved from a fat pig. The whole body is brownish red; Ears are of medium size, slightly upright, drooping in the middle and upper parts, slightly leaning forward; Short mouth, slightly concave skull; Big body, arched back, muscular hindquarters and stout limbs. Adult boars and sows weigh 340-400 kg and 300-390 kg respectively. Growing-finishing pigs can reach 90kg at 70 days old, the feed-to-weight ratio is below 2.8∶ 1, and the lean meat rate is 62% ~ 64%. Sexual maturity is late and reproductive ability is strong, with 10 ~ 12 sows.

This breed is usually the terminal male parent of binary hybridization and ternary hybridization, which has obvious effects on improving the weight gain speed, feed utilization rate and lean meat rate of commercial pigs.

Fig. 5 Hampshire pig, Duroc pig, native to the United States, has a black coat, but there is a white belt around the shoulder, chest and forelimbs at the junction of shoulder and neck, and a gray belt is formed by black and white hair at the white edge and black edge; The ears are erect, the mouth is thin and long, the body is long, and the hindquarters are muscular. Adult boars and sows weigh 3 15 ~ 4 10 kg and 250 ~ 340 kg respectively. Growing-finishing pigs 160 ~ 170 days old weigh 90kg, and the feed-to-weight ratio is (2.7 ~ 3. 1): 1. The carcass lean meat rate is over 60%, the muscle color is bright red and the meat quality is excellent. Medium fecundity, above the tail of multiparous sows.

Fig. 6 Three-way hybridization with Hampson as the male parent and three-way hybridization with Hampson as the terminal male parent have good hybridization utilization effect.

Pitland pig, native to Belgium. The whole body is gray and white with hair; Medium-sized ears, half forward; The body is wide and short, and the legs and buttocks are muscular. Adult boars and sows weigh 330kg and 220kg respectively. When slaughtered at 90kg, the proportion of hind legs was 33%, the area of eye muscles was 465,438 438±0 cm2, and the carcass lean meat rate was over 64%. The litter size of sows is small, and the litter size of multiparous sows is only about 8, but the parturient is good, and the reproductive rate of piglets can reach 92% ~ 98%.

Purebred Pitland pigs have high requirements on feeding conditions, are sensitive to climate and transportation, and often have stress symptoms such as trembling, shortness of breath, heart failure, sudden fainting and death. In the production of commercial pigs, it is suitable to be the terminal father, which has a good effect on improving daily gain, lean meat rate and feed utilization rate.

Fig. 7 Pitland pig