To maintain a lean pig breed and increase the lean meat percentage, several key factors must be carefully managed. Currently, local pig breeds in China have an average lean meat percentage of around 41%. Through extensive research, Nanjing Agricultural University developed a three-way crossbreed combining Duroc, Landrace, and Erhualian pigs. These pigs, when reaching 90 kg, showed a significantly improved lean meat content of up to 54%, with about 49 kg of lean meat per animal.
Feeding lean-type pigs requires a balanced diet tailored to their growth stages. For pigs weighing between 20 and 50 kg, the feed should provide approximately 3,100 kcal of digestible energy per kilogram. At this stage, the crude protein level should be around 16%. Once pigs reach 60 to 90 kg, the crude protein requirement drops to 14%, but essential amino acids like lysine, methionine, and cystine, along with other trace elements and vitamins, must be added in specific proportions to support optimal lean meat development.
For practical feeding, commercial concentrates from feed mills can be used, combined with ingredients such as corn, bran, rice bran, and soybean meal according to the manufacturer's instructions. This allows for the creation of a complete compound feed without the need to purchase individual supplements. If commercial concentrate is unavailable, the following formulas can be used:
1. For pigs weighing 10–20 kg: Corn 60.2%, Bran 4%, Soybean Meal 28%, Fish Meal 4%, Yeast Powder 2%, Salt 0.3%, Bone Meal 0.5%, Compound Trace Elements 0.5%, Multivitamins 0.5%.
2. For pigs weighing 21–35 kg: Corn 63%, Bran 10.2%, Soybean Meal 13.5%, Rapeseed Cake 6%, Fish Meal 5%, Salt 0.3%, Bone Meal 1%, Compound Trace Elements 0.5%, Multivitamins 0.5%.
3. For pigs weighing 36–60 kg: Corn 62%, Bran 12%, Gluten 5%, Soybean Meal 10%, Rapeseed Cake 5%, Fish Meal 3.5%, Salt 0.5%, Bone Meal 1%, Compound Trace Elements 0.5%, Multivitamins 0.5%.
4. For pigs weighing 61–90 kg: Corn 57%, Bran 18%, Bran 6%, Soybean Meal 9%, Rapeseed Cake 5%, Yeast Powder 3.3%, Salt 0.5%, Bone Meal 1%, Compound Trace Elements 0.1%.
The feeding strategy also plays a crucial role. The "open front and rear control" method is recommended. Before reaching 50 kg, pigs are fed freely multiple times a day. After 50 kg, feeding is restricted to two meals per day, with only 80% of the full ration provided. This helps reduce fat deposition and preserve lean meat. Studies show that during the 40–60 kg phase, daily lean meat gain is about 288g, while fat gain is 280g. However, after 90 kg, lean meat growth slows to just 120g per day, with fat gain being twice that of lean meat. Therefore, it is best to slaughter lean-type pigs between 90 and 100 kg to maximize lean meat yield.
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