Growing pigs can be divided into three distinct growth stages based on their weight: the growing phase (20–35 kg), the mid-growth phase (35–60 kg), and the finishing phase (60 kg until market). Among these, the growing phase is particularly critical, as this is when pigs are most susceptible to disease and environmental stress. Once they reach the finishing stage, feeding and management become more straightforward.
In terms of feed energy levels, pigs up to 60 kg are usually allowed free-choice feeding. If the digestible energy per kilogram of feed ranges between 2950–3300 kcal, the pig can regulate its intake accordingly. However, during periods of low market prices, some farmers may cut costs by using ingredients like wheat bran, which often lowers the energy content to the minimum of 2950 kcal/kg. This can significantly slow down growth and reduce feed efficiency, ultimately delaying slaughter time. For pigs under 60 kg, it’s recommended that the diet provide at least 3200 kcal/kg of digestible energy, and after that, it can be slightly reduced to 3100 kcal/kg.
Once pigs reach 60 kg, feeding restrictions are typically introduced. However, if producers aim for rapid growth and early slaughter, free feeding can still be used. For those focusing on lean meat production, strict feed restriction (around 65% of free intake) is advised. A moderate restriction (75–80% of free intake) is generally preferred, as it helps maintain a high lean meat percentage without significantly affecting weight gain, leading to better overall profitability.
Protein and essential amino acid levels in feed also vary depending on whether the goal is lean or fat-type pork. In the small and medium pig stages, crude protein should be around 18% and 16%, respectively, while fat-type pigs require about 2% less. In the large pig stage, 14% crude protein is sufficient. Each 1% increase in dietary protein can boost carcass lean meat content by 0.5%. However, due to the high cost of protein sources, using high-protein diets for higher lean yield is often not economically viable.
The real need for protein in pigs is actually a need for amino acids. Since the 1970s, the concept of "ideal protein" has been widely adopted, especially after Dr. Cole from the UK proposed it. Feed manufacturers now focus on balancing essential amino acids, with lysine typically set at 100 as a reference point, and other amino acids calculated relative to it.
Proper management is crucial for growing and finishing pigs. Before entering the barn, thorough disinfection is necessary. Only healthy, high-quality piglets should be selected, and proper vaccination and deworming must be done. Pigs of similar weights should be grouped together to reduce competition. Establishing consistent routines for eating, sleeping, defecating, and drinking helps build a conditioned reflex.
Stocking density should be kept reasonable: 0.3–0.5 m² per pig for small pigs, 0.6–0.7 m² per pig for medium-sized pigs, and 0.8–1.0 m² per pig for large ones. The ideal temperature range for growing pigs is 16–22°C for small and medium pigs, and 14–20°C for larger pigs. Extreme temperatures can negatively affect growth and feed conversion.
During hot weather, ventilation should be improved, and clean water must always be available. Spraying cool water on the floor can help lower the ambient temperature. In winter, pigs need more energy to maintain body heat, so feeding should be adjusted accordingly. Grouping pigs together and providing some roughage can help conserve energy and protect against cold.
Finally, regular cleaning of the barn is essential to maintain a clean and dry environment, reducing harmful gases and improving overall health and productivity.
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