Standardized ileal digestibility (SID, %) of crude protein (CP) and amino acid (AA) and the metabolic availability (MA) of Met using the indicator amino acid oxidation (IAAO) method, in partially defatted black soldier fly larvae (PD-BSFL) meal were determined in growing pigs in 2 experiments. The Met SID value was then compared numerically with the Met MA to understand how different SID is compared with its MA value. In Exp. 1, 6 ileal-cannulated barrows (initial body weight [BW] = 18.03 ± 0.34 kg) were used in a 2-period switch back design and fed either a nitrogen-free diet (NFD) or test diet, with PD-BSFL meal as the sole source of AA, over two 11-d experimental periods, at a feeding level of 2.8 x estimated maintenance digestible energy requirement. Barrows were adapted for 9-d to the diet, followed by continuous 8-h ileal digesta collection on days 10 and 11. Digesta were pooled per pig within period. The SID of CP and Met of PD-BSFL meal were 76.1 ± 6.2% and 90.4 ± 3.9 %, respectively. In Exp. 2, 7 barrows (initial BW = 18.77 ± 0.69 kg) were used in a 7 × 7 Latin square design with L-[1- 13C]-Phe as the indicator AA. Each pig was randomly assigned to 1 of 7 dietary treatments over seven 3-d experimental periods. Two diet types were studied including reference (crystalline AA) and PD-BSFL test diets, each supplying graded intakes of Met at 55, 65, and 75% of the estimated SID requirement (NRC, 2012). The MA of Met was determined by comparing the IAAO response between the reference and PD-BSFL test diet using the slope-ratio method. Linear regression determined a negative slope of the best fit line for both the reference and test diets (P < 0.05). The MA of Met in PD-BSFL meal was 53.3%, which is as expected lower than the SID value. While it is generally appreciated that MA will be less than SID, the use of SID is more practical. In cases where SID cannot explain physiological outcomes of feeding a novel ingredient, IAAO may provide additional insight into whether MA should be explored.

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Empirical growth models have widespread application in the field of aquaculture. These models allow estimates of harvest size and waste outputs in addition to nutrient and feed requirements. In an effort to increase the ability to predict shrimp growth, the specific growth rate (SGR) and thermal‐unit growth coefficient (TGC) models were fitted to 15 datasets encompassing growth of Pacific whiteleg shrimp (Litopenaeus vannamei). Shrimp were reared under commercial conditions in Southeast Asia with weights ranging from 0.01 g to 34 g. Growth rates were regressed against body weights to identify changes in growth pattern across life stages. Analysis identified two distinct patterns of growth, with a break point between stanzas at 7.5 g. The body weight exponent of the TGC model, traditionally assumed to be (1 − b) = 1/3, was solved for iteratively in each identified growth stanza in an effort to improve the goodness of fit of the TGC model. Average body weight exponents in the first and second stanzas were 0.416 and 0.952 respectively. Projected growth trajectories using these exponents resulted in significantly better fits in comparison to the traditional TGC and the SGR on the basis of statistical measures of goodness of fit.

New ingredients need to be characterized both chemically and in vivo, then compared to commonly-used protein ingredients before they can be considered for use in feeds. The objective of the present study was to determine the standardized ileal digestibility (SID, %) of amino acids (AA) of partially defatted black soldier fly larvae meal (BSFLM) (49.7% CP; 14.4% crude fat as fed). Subsequently, these results were compared to the SID AA of common protein ingredients in swine feed, fish meal (FM) and soybean meal (SBM) (NRC 2012), and to published full-fat (FF) BSFLM SID values. Six ileal-cannulated barrows (18.03 ± 0.67 kg BW) were used in a 2x2 Latin square design and fed either a nitrogen-free diet (NFD) or BSFLM-containing diet over two 11-d experimental periods. In each period, barrows were adapted for 7 days to the diet and ileal digesta collection was conducted on day 10 and 11 for 8h per day. Basal endogenous AA losses (EAAL) were calculated from pigs fed the NFD and as expected, the ileal AA content were significantly higher for pigs fed the BSFLM diet than NFD (P < 0.05). SID for AA were then calculated based on the obtained EAAL values following Stein et al., 2007. For essential AA, the SID of BSFLM were all above 82%, the highest being Arg (93.76%), followed by Met (91.32%), and Phe (89.80%). The SID of essential AA were on average 5.0% higher in BSFLM than FM, but 2.7% lower than SBM. When compared to the FF BSFLM, SID of essential AA of BSFLM were 1–5% higher, except for Phe and Thr. These results suggest that partially defatted BSFLM is a promising alternative protein ingredient in growing pig diets, which has a more digestible AA profile than FM, only slightly lower than SBM, and comparable to the FF BSFLM.

The objective of this study was to determine the standardized ileal digestibility (SID) of protein and amino acids (AA), and calculate the digestible indispensable AA score (DIAAS) of three varieties of Canadian grown pulses (faba bean, lentil, yellow pea). Three steam-pelleted (80 ℃) diets (faba/lentil/pea; 40% inclusion) and a nitrogen free diet were fed to 8 cannulated growing pigs in a 4 × 4 replicated Latin square design. The SID values were used to calculate DIAAS. There were no differences in SID of protein and AA when all diets were compared (P > 0.05). The SID of methionine was 95% for faba beans, 96% for lentils, and 96% for peas. The SID of lysine was 93% for faba beans, 92% for lentils, and 90% for peas. Tryptophan had the lowest SID across all indispensable AA of all pulses (59% faba, 61% lentil, 41% pea). All other indispensable AA SID were above 80%. Tryptophan was the limiting indispensable AA for all pulses as determined by DIAAS, with scores of 30 (faba), 57.83 (lentil), 27.27 (pea). These values will aid in optimal inclusion of steam-pelleted pulses in diets for swine and provide insight on the protein quality of pulses for humans.