Commercially available avian and mammalian whole prey diet items targeted for consumption by managed exotic and domestic pet felines: True metabolizable energy and amino acid digestibility using the precision-fed cecectomized rooster assay

Abstract

Whole prey diets are commonly used in the zoo and home setting for captive exotic and domestic cats, respectively. Despite their increase in popularity, nutrient digestibility of such diets has been poorly studied. In this study, the precision-fed cecectomized rooster assay was used to determine the protein quality and nitrogen-corrected true ME (TMEn) of 17 whole prey samples (mice [1 to 2 , 10 to 13 , 21 to 25 , 30 to 40 , and 150 to 180 d old], rats [1 to 4, 10 to 13, 21 to 25, 32 to 42, and >60 d old], rabbits [stillborn, 30 to 45 d old, and >65 d old], chicken [1 to 3 d old], and quail [1 to 3, 21 to 40, and >60 d old]) and 2 ground poultry-based products (chicken and duck). Amino acid score (AAS) and protein digestibility corrected AAS (PDCAAS) were calculated using the nutrient profile recommendations for domestic cat food as a reference value (AAFCO, 2012). Average individual indispensable AA (IAA) and total IAA (TIAA) digestibility coefficients were variable anddepended on AA (84 to 94% TIAA, 85 to 95% Arg, 87 to 96% His, 82 to 92% Ile, 84 to 94% Leu, 85 to 93% Lys, 89 to 97% Met, 83 to 94% Phe, 80 to 95% Thr, 84 to 94% Trp, and 80 to 93% Val) and sample. For a majority of the whole prey items, AA concentrations were greater than the Association of American Feed Control Officials ( AAFCO: , 2012) domestic cat nutrient profile recommendations for growth and reproduction and adult maintenance; however, some whole prey had AA concentrations below the AAFCO (2012) recommendations: Met + Cys (1.10% DM) in ground duck (1.06% DM) and taurine (Tau; 0.20% DM) in 30-to-45- and >65-d-old rabbits (0.01 and 0.10% DM, respectively), 150-to-180-d-old mice (0.18% DM), and ground duck (0.15% DM). The TMEn (3.76 to 6.44 kcal/g DM) expressed as the percent of GE (i.e., TMEn/GE) ranged from 66 to 85%, demonstrating how variable the digestibility of these items may be and justifying more research in this area. Both Met and Tau are commonly added to commercial pet foods, so supplements are readily available to address potential deficiencies and improve protein quality. A direct comparison of the ME of whole prey items by in vivo feline and rooster experiments is needed.

Chemical composition, true nutrient digestibility, and true metabolizable energy of chicken-based ingredients differing by processing method using the precision-fed cecectomized rooster assay1

“…When compared with the digestibility data of chicken meal reported by Deng et al (2016), the chicken meal in the current study had similar responses, but higher isoleucine, lysine, methionine, tryptophan, and glutamic acid digestibilities. The ground chicken reported by Kerr et al (2014) had similar AA digestibilities to the steamed chicken in the present study, with the exceptions of histidine and threonine that were more digestible in the ground chicken. Compared with the high-and lowash PBP reported by Johnson et al (1998), all AA digestibilities with the exception of cysteine, glycine, and serine were higher in chicken meal from the present study, but similar to PBP with high-ash content.…”

“…However, the chicken breast from the Faber et al (2010) study had higher indispensable AA concentrations than all of the chicken-based ingredients tested in the present study. The ground chicken reported by Kerr et al (2014) had similar concentrations of indispensable AA with the chicken meal, retorted chicken, and steamed chicken tested in the present study. For the dispensable AA, the chicken meal tested by Deng et al (2016) had similar concentrations of aspartic acid, glutamic acid, and glycine to the chicken meal tested in the present study.…”

“…However, cysteine had a much lower digestibility value in the present study (50.2% raw chicken and 52.9% retorted chicken) compared to that of Faber et al (2010;82.0% chicken breast). Cysteine is a component of keratin and other fibrous proteins, and typically has a lower digestibility (Kerr et al, 2014). One must consider the low digestibility of cysteine (range from 50.22% to 68.37% in present study) and low methionine DIAAS-like value for chicken meal (78.10) when formulating diets, especially when using meals that have undergone rendering and drying processes due to the fact that cysteine is supported by the metabolism of methionine (Weichselbaum et al, 1932).…”

Environmental and prey‐based factors underpinning variability in prairie dogs eaten by black‐footed ferrets

“…The nutrient composition of whole vertebrate prey consumed by carnivores is important to understand from both an ecological and management perspective. However, such datasets are scarce in the published literature (see for example Dierenfeld et al 2002, Kremer et al 2013, Kerr et al 2014 a , b ). For the most part, analyses have focused on proximate composition (water, crude protein, crude fat, and ash), with energy content and some minerals quantified.…”

“…For the most part, analyses have focused on proximate composition (water, crude protein, crude fat, and ash), with energy content and some minerals quantified. More recent studies have started filling data gaps with detailed assays of amino acid (Kremer et al 2013, Kerr et al 2014 a ) and fatty acid profiles (Kerr et al 2014 b ), but there is still a dearth of information on essential nutrients such as fat‐soluble vitamins. Furthermore, variables known to impact nutritional content of whole prey across species, such as sex and age (see Douglas et al 1994), diet (Clum et al 1996), seasonality, and/or the consequences of not analyzing the prey in the same form as eaten (e.g., eviscerated vs complete, or with or without fur/feathers/skin), have not been fully explored.…”