What are the effects on nursery pig performance ?
By Ethan B. Stas, Mike D. Tokach, Jason C. Woodworth, Joel M. DeRouchey, Robert D. Goodband, and Jordan T. Gebhardt
Newly weaned pigs undergo a dramatic change in diet composition from a highly palatable and digestible milk diet to a dry cereal-based diet. At weaning, pigs have limited ability to produce enough hydrochloric acid in the stomach to maintain an acidic environment. As a result, early nursery pigs can experience a high gastric pH which can lead to decreased protein digestion and increased opportunity for pathogens to compromise the digestive tract.
Poor acidification of the stomach can be attributed to the high acid-binding capacity of feed ingredients. Acid-binding capacity-4 (ABC-4) is the amount of acid required to lower an ingredient to a pH of 4. The use of low acid-binding ingredients (avoidance of high acid-binding ingredients) in diets of newly weaned pigs could be utilized to maintain an acidic environment in the stomach.
Specialty protein sources are often used in early nursery diets as a partial replacement to soybean meal because of soy’s antinutritional factors.
However, the ABC-4 of specialty soy products can vary depending on how the soy protein is processed influencing the overall diets ABC-4. Incorporating a specialty protein source with a low ABC-4 in early nursery diets may improve the health status and performance of newly weaned pigs.
Added Zn from Zn oxide is another common nutritional intervention to protect the digestive tract from pathogens and improve pig performance. The inclusion of pharmacological levels of Zn has been shown to reduce diarrhea and improve performance of nursery pigs. However, there are growing concerns with the use of ZnO at pharmacological levels.
Our hypothesis was that in diets without added ZnO, a low ABC 4 may improve gut health and subsequent performance of early nursery pigs and provide some of the same benefits as pharmacological levels of Zn.
Therefore, two studies were conducted to evaluate ABC-4 of common North American feed ingredients and to determine the effect of diet ABC-4 level with or without ZnO on nursery pig performance.
Experiment 1In the first study, common feed ingredients used in North America were collected from commercial sources and measured for ABC-4. All ingredient samples were ground to a consistent particle size before analysis.
One-half gram samples of each ingredient was suspended in 50 mL of distilled deionized water. Titrations were performed by the addition of 0.1 N hydrochloric acid to reach a stable pH of 4.
Acid-binding capacity-4 was calculated as the amount of acid in milliequivalents (meq) required to achieve pH of 4 for 1 kg of sample. Ingredients were grouped into categories: cereal grains, vegetable proteins, animal proteins and milk, vitamin premixes and minerals, amino acids, and fiber sources.
Cereal grains with respect to other ingredients were found to have low ABC-4. Specifically, corn was measured at 84 ± 18.6 meq/kg. Vegetable proteins were among two ingredient categories with the most variation between ingredients and sources. Soybean meal was found to have an ABC-4 of 602 ± 28.2 meq/kg. Specialty soy products ranged from -13 to 753 meq/kg. Therefore, specialty soy source can have a large effect on the overall diets ABC-4 value.
Vitamin premixes and minerals had the highest ABC-4 between categories with the most variation. Calcium carbonate and ZnO had the highest ABC-4 of 18,384 ± 769.7 and 21,863 ± 598.7 meq/kg, respectively.
Although a high ABC-4 is thought to be detrimental to the newly weaned pigs, it is likely the beneficial antimicrobial properties of ZnO outweigh the potential negative effects of increased ABC-4 of the diet. However, limiting the calcium content in diets of early nursery pigs could be used to achieve a low ABC-4 of the diet.
Experiment 2The second study utilized ingredient values from the previous study to formulate diets to a specific ABC-4 value. Diets were arranged in a 2 × 2 factorial with low or high ABC-4 levels with or without pharmacological levels of Zn from ZnO.
The low ABC-4 diet was achieved by utilizing a novel soy protein concentrate (AX3 Digest; Protekta; Plainfield, Indiana) while the high ABC-4 diet was formulated with enzymatically treated soybean meal (HP 300; Hamlet Protein; Findlay, Ohio).
The low ABC-4 diets without ZnO were formulated to 150 and 200 meq/kg in phase 1 and 2, respectively. Replacing novel soy protein concentrate with enzymatically treated soybean increased the ABC-4 of the diet by approximately 104 to 127 meq/kg.
Diets with pharmacological levels of Zn contained approximately 2,000 ppm of Zn from ZnO in phase 1 and 2. The ZnO increased the ABC-4 of the diet by approximately 60 to 65 meq/kg. Dietary treatments were fed in two phases from d 0 to 7 and d 7 to 21, followed by a common diet for an additional 21 d.
An interaction between ABC-4 level and ZnO, particularly in the experimental period, was observed. When ZnO was present in the diets, there were no differences in performance between the low and high ABC-4 level. However, when ZnO was not present in the diet, pigs fed the low ABC-4 diet had improved weight gain and feed efficiency.
Additionally, pigs fed the low ABC-4 had lower removals and mortalities compared to a high ABC-4 diet when ZnO was not included in the diet. Similar to previous research, pharmacological levels of Zn from ZnO was able to improve performance compared to diets without ZnO.
The results of both studies indicate ABC-4 can be adjusted through careful selection of feed ingredients. Feeding a low ABC-4 diet for the first few weeks post weaning can improve growth performance, morbidity, and mortality when pharmacological levels of Zn are not present in the diet. Full reports and results can be found in the 2022 Swine Day Publications.
Table 1 resources:
1 Acid-binding capacity-4 was determined by the amount of 0.1 N HCl required to lower the initial pH of a sample to a stable pH of 4.00 ± 0.04. Each sample was analyzed three times and value reported is average of sample means ± standard deviation of sample means.2 Number of samples analyzed, with each sample analyzed in triplicate.3 Buffering capacity is calculated as ABC-4 divided by the total change in pH.4 Xsoy, CJ Bio, Seoul, South Korea; SoyTide, CJ Bio, Seoul, South Korea.5 MEpro, Prairie AquaTech, Brookings, SD; Fermex, Purina Animal Nutrition, Shoreview, MN; Proplex T, ADM Animal Nutrition, Quincy, IL.6 AX3, Protekta, Plainfield, IN.7 HP 300, Hamlet Protein, Findlay, OH.8 NexPro, Poet, Sioux Falls, SD; Protomax, ICM, Colwich, KS.9 TASA, Lima, Peru; Omega Protein, Houston TX.10 APC, Ankeny, IA.11 AV-E Digest, XFE Products, Des Moines, IA.
Table 2 Resources: 1 A total of 1,057 pigs (initial BW of 13.7 ± 0.79 lb) were used in a 42-d nursery trial. A total of 4 dietary treatments were arranged in a 2 × 2 factorial design consisting of low or high ABC-4 of the diet with or without the presence of ZnO. There were 22 pigs per pen and 12 replications per treatment. 2Diets contained 2,265 and 2,121 ppm of Zn from ZnO in phase 1 and 2, respectively. 3The low ABC-4 diets were formulated with a specialty soybean meal (AX3 Digest; Protekta; Plainfield, IN) and the high ABC-4 diets were formulated with enzymatically treated soybean meal (HP 300; Hamlet Protein; Findlay, OH). The low ABC-4 diet without ZnO was formulated to a value of 150 and 200 meq/kg in phase 1 and 2, respectively. The addition of ZnO increased the ABC-4 of the diet by approximately 60 to 65 meq/kg. Replacing specialty soybean meal with enzymatically treated soybean meal increased the ABC-4 of the diet by 104 to 127 meq/kg. 4BW per pig placed = final ending weight ÷ pigs placed. 5F/G was calculated from G:F by taking the inverse, therefore the P values are the same and there are no reported SEM. 6ADG per pig placed = (final ending weight – initial weight) ÷ (Pigs initially placed × days of trial). 7ADFI per pig placed = (total feed intake) ÷ (Pigs initially placed × days of trial). 8The research site experienced a significant PRRSV health challenge on approximately d 15 of the trial. 9Percentage of pigs that were removed into a hospital pen and lived until d 42. Does not include pigs that were removed and died/euthanized in hospital pen. 10Percentage of pigs that died/euthanized in original pen or hospital pen after being removed.
Stas is a swine nutrition graduate student, Tokach and Goodband are university distinguished professors, Woodworth is a research professor, DeRouchey is a professor/state extension leader, and Gebhardt is an assistant professor, all at Kansas State University.
