Liquid Diets Improve Performance of Early-Weaned Pigs

Ever since segregated early weaning (SEW) arrived on the North American swine scene some 10 years ago, researchers and producers alike have been trying to figure out the best way to feed these early-weaned pigs. Weaning pigs at 14-17 days of age, and sometimes younger, became popular from the perspective of disease control. However, post-weaning management of these SEW pigs has evolved and changed over the years as the industry has struggled to understand the challenges associated with the dramatic adjustment these young pigs must make from sow's milk to dry feed.

The stress of switching to a dry diet at such a young age, with the potential for accompanying health challenges, can result in prolonged growth checks, high morbidity and mortality in the nursery. In addition, poor growth performance early on can translate into subsequent problems in the growing and finishing phase, increasing days to market and variation in performance significantly. Improving feed intake during the post-weaning period is very important for encouraging development of the small intestine and subsequent growth performance.

The goal in feeding weaned pigs is to meet their nutritional requirements for performance and health, while minimizing the post-weaning check, and ultimately to do so economically. Early-weaned pigs are at a disadvantage because their digestive systems are not adequately developed to handle the digestion and absorption of a typical weaning diet based on grains and vegetable proteins. The digestive enzymes that break down sugars, starch and protein take a considerable amount of time to reach maturity and can be extremely variable between pigs. As a result, it is common for pigs at this stage to experience a growth lag.

Feeding a high-quality post-weaning diet is critical to help the pig make the transition from highly digestible sow's milk to less-digestible grain-based diets. In order to maximize growth, weaned pigs are currently being fed highly digestible and very expensive diets containing milk and plasma proteins. A diet that would reduce the adaptation time of the pig to the post-weaning diet would be beneficial to both the pig and the producer.

Researchers at North Carolina State University recently reported the results of an experiment looking at the potential for a liquid diet to support improved growth rates in early-weaned pigs. The objectives were to examine the effect of diet physical form and nursery environment on performance of very early-weaned pigs and to determine if any early growth advantages that were realized could be maintained through to market weight. A total of 240 pigs (11 days of age, 3.93 kg initial body weight) were used in the experiment, which examined the following factors:

The liquid and dry pelleted diets were formulated to be identical nutritionally, with the liquid diet being offered at 15-16% dry matter. Pigs were housed in either a specialized segregated-temperature nursery, which had hot (32°C) and cool (24°C) compartments, or the conventional nursery, which was maintained at 27 to 34°C. To assist in the transition from liquid to dry feed, pigs on the liquid diet were offered dry pellets from day 12 to 14. After 14 days, all pigs were moved into the conventional nursery facilities and fed identical diets up to 60 days of age. The pigs were then moved into grower-finisher facilities and grouped by gender. All diets used throughout the experiment were formulated to exceed NRC (1998) nutrient requirements. Some of the experimental data is summarized in Table 1.

The physical form of feed had a significant impact on growth performance of early-weaned pigs. At day 14 after weaning, pigs fed the liquid diet were 21% heavier and had average daily gains 44% greater than pigs fed the nutritionally identical diet in dry form. Liquid feeding showed the greatest advantage during the first 3 days after weaning, when liquid fed pigs gained almost 4 times faster than the dry-fed controls (248 vs. 64 g/day). However the difference in average daily gain between liquid and dry fed pigs quickly decreased as the animals aged.

Increased feed intakes and gain:feed ratios supported accelerated growth in the liquid fed pigs. As a result, at the end of the nursery period, liquid-fed pigs weighed 2.4 kg more than dry-fed pigs. The difference was most evident among pigs reared in the conventional hot nursery. It is interesting to note that, during day 15-49, pigs fed the liquid diet within the conventional hot nursery continued to out-perform their dry fed controls. In contrast, the added stress of diet change and relocation of the liquid-fed pigs from the segregated-temperature nursery caused their performance to lag behind the dry-fed pigs during this same period.

Overall, pigs fed the liquid diet during the first 2 weeks post-weaning performed better, showing greater average daily gain and average daily feed intake results. As a result, liquid fed pigs required fewer days to reach the target market weight of 110 kg (150.9 vs. 154.6 days for liquid and dry-fed pigs, respectively). In addition, pigs fed the liquid diet had thicker backfat compared to pigs fed the dry pellets during the first 2 weeks post-weaning. However, the apparent body composition changes reported during the nursery period were not maintained through to the growing-finishing phase of development. Other researchers have reported similar results, indicating that body composition early in life has little or no influence on body composition at time of slaughter.

This study clearly indicates the benefits of liquid feeding for early-weaned pigs within conventional hot nursery systems. This study is the first to attribute the improved performance to the physical form of feed and to document that the growth advantage of liquid-fed pigs is maintained to market weight. The researchers suggest that if this technique is selectively applied to pigs with lighter weaning weights, liquid feeding in the nursery could be useful in reducing variation in market weight and days to market.