The use of microbial phytase is often used in growing pig feed due to the demonstrated effectiveness of phytase in increasing the digestibility of phosphorus and calcium. It is sometimes claimed that phytase can increase the digestibility of energy, and phytase companies sometimes offer their customers a matrix value that can be used to lower the spec energy of a pig’s diet. In experiments, researchers were unable to demonstrate an increase in digestible and metabolizable energy in diets containing phytase, so it is somewhat controversial whether microbial phytases actually increase energy digestibility.
Most energy balance experiments are performed with pigs grown individually housed in metabolic crates, whereas on commercial farms pigs are housed in groups and share the same feeder within the same pen. However, to our knowledge, there is no information on the effects of microbial phytases on maize energy digestibility when fed to group-reared pigs.
Therefore, the aim of this experiment was to demonstrate that the addition of microbial phytase to a maize-based diet increased nitrogen balance and, therefore, the apparent total tract digestibility of total energy, DE and ME by group-fed growing pigs. was to test the hypothesis that the
Three diets were prescribed. One diet contained maize (GE = 3,844 kcal/kg; dry matter = 88%) as the sole energy source and this diet was the positive control diet. PC diets contained Ca and P required by pigs (NRC, 2012). There were two negative control (NC) meals. One NC diet also contained maize as the sole energy source, but contained 0.08% standardized total tract digestible P and 0.12% total Ca than the PC diet. The second NC diet was similar to the first NC diet, except this diet contained 1,000 units of phytase per kg of diet.
A total of 24 pigs (initial weight: 45.0 kg) were housed in groups of 4 pigs in 6 metabolic crates and assigned to 3 diets using a replicated 6 × 3 incomplete Latin square design, A total of 6 trials of 3 baits and 3 periods were used. Observations per meal. Each crate was equipped with a slatted floor, a stainless steel fecal screen, and a urine dish for complete but separate collection of feces and urine. Pigs were fed ad libitum and had free access to water at all times. After 7 days of acclimatization, total fecal and urine samples were collected for 6 days. Her ATTD of dry matter, GE and N, retention of N, and concentrations of DE and ME in feed and maize were calculated.
Results showed that dry matter ATTD, N ATTD, N retention, GE ATTD, and fecal and urinary energy excretion did not differ among the three diets (Table 1). However, concentrations of DE ME in feed and maize were low (P. P.
In conclusion, N balance and concentrations of DE and ME were not affected by adding microbial phytase to maize-based diets, but the ratio of ME to DE was increased by phytase supplementation. Therefore, we could not confirm the hypothesis that microbial phytases increase DE and ME in maize-based diets fed to group-reared growing pigs.