The effect of reduced cp, synthetic amino acid supplemented diets on growth performance and nutrient excretion in wean to finish swine

Authors: VONDEROHE, CAITLIN - Baylor College Of Medicine; Mills, Kayla; LIU, SHULE - University Of California, Davis; ASMUS, MATTHEW - Purdue University; OTTO-TICE, EMILY - Purdue University; RICHERT, BRIAN - Purdue University; NI, JI-QIN - Purdue University; RADCLIFFE, JOHN SCOTT - Purdue University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2022
Publication Date: 5/9/2022
Citation: Vonderohe, C., Mills, K.M., Liu, S., Asmus, M.D., Otto-Tice, E., Richert, B.T., Ni, J., Radcliffe, J. 2022. The effect of reduced cp, synthetic amino acid supplemented diets on growth performance and nutrient excretion in wean to finish swine. Journal of Animal Science. https://doi.org/10.1093/jas/skac075.
DOI: https://doi.org/10.1093/jas/skac075

Interpretive Summary: The use of swine manure for fertilizer is a common and effective manure management tool in the swine industry. Nitrogen naturally present in manure can leach from fields after application causing an excess of nutrients within bodies of water which can be harmful for aquatic ecosystems or negatively impact drinking water. Producers have already reduced nitrogen content within manure by supplementing pigs with synthetic amino acids (AA) and reducing dietary crude protein (CP). However, it has been observed that growth is slowed when CP is excessively reduced. Therefore, in this study we examined the effects of using different levels of synthetic AAs and reduced CP on body weight gain, feed conversion ratio, feed intake, carcass characteristics, and nitrogen excretion. Pigs were fed in nine phases across the wean-finish program and were fed one three diets. The control diet was a corn-soybean meal-distiller’s dried grains with soluble (DDGS) containing minimal to no (Met) synthetic AA. The 2X diet was formulated to meet the seventh most-limiting AA and balanced using synthetic AAs to meet all AA needs. The 1X diet was formulated to meet a CP value halfway between the control and 2X diet, also balanced using synthetic AAs to meet all AA needs. All diets were formulated to identical net energy concentrations and balanced to meet NRC 2012 AA requirements. Pigs fed the control and 1X diet grew faster, had greater feed conversion, and were heavier at market than animals fed the 2X diet. Total mineral excretion per kg of gain was reduced in pigs fed 1X and 2X diets compared to control-fed pigs. Reductions in CP of approximately three and five percent from wean-finish resulted a reduction of total nitrogen by 11.7 and 24.4%, respectively. Reduced growth performance observed in pigs fed the 2X diet suggests that the NRC 2012 AA requirements or ratios to lysine may need to be reevaluated before we can effectively reduce dietary CP any further.

Technical Abstract: Mixed sex pigs (n = 720) were placed in 12 rooms (Purdue Swine Environmental Research Building) to measure the effect of reduced crude protein (CP), amino acid (AA)-supplemented diets on growth and the carcass. Pigs were blocked by body weight (BW) and gender and allotted to room and pen (10 mixed-sex pigs/pen). Pigs were fed a 9-phase, wean-finish program. Control pigs consumed corn-soybean meal-distiller’s dried grains with soluble (DDGS) diets containing no to minimal (Met) synthetic AA. The 2X diet was formulated to meet the seventh most-limiting AA and balanced using synthetic AAs to meet all AA needs. The 1X diet was formulated to meet a CP value halfway between the control and 2X diet, and also balanced using synthetic AAs to meet all AA needs. Diets were formulated to identical net energy concentrations and balanced to meet standard ileal digestible NRC 2012 AA requirements. Pit vacuum samples were collected at the end of each growth phase for analyses of nitrogen, C and dry matter (DM). Pigs fed the Control and 1X diet grew faster (P< 0.005), had greater gain: feed (P < 0.001), and were heavier at market (P < 0.001) than animals fed the 2X diet. No consistent effects of diet were observed on average daily feed intake. Carcass data were analyzed for sex, diet and sex*diet effects. Reductions in dietary CP resulted in a linear reduction in ammonium nitrogen excretion per kg of BW gain in Nursery (P<0.001) and Grow-Finish (P<0.001) phases. Reductions in dietary CP, with synthetic AA supplementation resulted in a linear reduction in total nitrogen excreted per kg BW gain in the Grow-Finish phase (P<0.001) and overall (P<0.001). Total mineral excretion per kg gain was reduced in pigs fed 1X and 2X diets compared with control-fed pigs (P < 0.005). Reductions in dietary CP of ~3 and 5%-units from wean-finish result in reductions of total N excretion of 11.7 and 24.4%, respectively. Reduced performance and carcass characteristics observed in pigs fed the 2X diets indicates an inaccurate estimate of NRC 2012AA requirements or ratios to lysine in a low CP diet.