Apparent Total Tract Digestibility Of Nutrients Research Articles

Lactational performance, rumen fermentation, and enteric methane emission of dairy cows fed an amylase-enabled corn silage

This study investigated the effects of an amylase-enabled corn silage on lactational performance, enteric CH4 emission, and rumen fermentation of lactating dairy cows. Following a 2-wk covariate period, 48 Holstein cows were blocked based on parity, days in milk, milk yield (MY), and CH4 emission. Cows were randomly assigned to 1 of 2 treatments in an 8-wk randomized complete block design experiment: (1) control corn silage (CON) from an isogenic corn without α-amylase trait and (2) Enogen hybrid corn (Syngenta Seeds LLC) harvested as silage (ECS) containing a bacterial transgene expressing α-amylase (i.e., amylase-enabled) in the endosperm of the grain. The ECS and CON silages were included at 40% of the dietary dry matter (DM) and contained, on average, 43.3 and 41.8% DM and (% DM) 36.7 and 37.5% neutral detergent fiber, and 36.1 and 33.1% starch, respectively. Rumen samples were collected from a subset of 10 cows using the ororuminal sampling technique on wk 3 of the experimental period. Enteric CH4 emission was measured using the GreenFeed system (C-Lock Inc.). Dry matter intake (DMI) was similar between treatments. Compared with CON, MY (38.8 vs. 40.8 kg/d), feed efficiency (1.47 vs. 1.55 kg of MY/kg of DMI), and milk true protein (1.20 vs. 1.25 kg/d) and lactose yields (1.89 vs. 2.00 kg/d) were increased, whereas milk urea nitrogen (14.0 vs. 12.7 mg/dL) was decreased, with the ECS diet. No effect of treatment on energy-corrected MY (ECM) was observed, but a trend was detected for increased ECM feed efficiency (1.45 vs. 1.50 kg of ECM/kg of DMI) for cows fed ECS compared with CON-fed cows. Daily CH4 emission was not affected by treatment, but emission intensity was decreased with the ECS diet (11.1 vs. 10.3 g/kg of milk, CON and ECS, respectively); CH4 emission intensity on ECM basis was not different between treatments. Rumen fermentation, apart from a reduced molar proportion of butyrate in ECS-fed cows, was not affected by treatment. Apparent total-tract digestibility of nutrients and urinary and fecal nitrogen excretions, apart from a trend for increased DM digestibility by ECS-fed cows, were not affected by treatment. Overall, ECS inclusion at 40% of dietary DM increased milk, milk protein, and lactose yields and feed efficiency, and tended to increase ECM feed efficiency but had no effect on ECM yield in dairy cows. The increased MY with ECS led to a decrease in enteric CH4 emission intensity, compared with the control silage.

Apparent total tract nutrient digestibility and metabolizable energy estimation in commercial fresh and extruded dry kibble dog foods.

Commercial fresh cooked foods have started gaining popularity among American dog owners in recent years. However, nutrient digestibility and the estimation of metabolizable energy (ME) of commercial fresh dog foods remain inadequately understood, even though both measures are critical to provide the intended calories for the target animal. In this preliminary study, different cohorts of normal-weight dogs were fed one of five test diets of comparable macronutrient composition: a chicken-based extruded dry kibble diet (n = 12), and chicken- (n = 12), beef- (n = 6), pork- (n = 6), or turkey-based fresh food (n = 6) for 10 d. Daily food intake and fecal characteristics were recorded, and fecal samples were collected for nutrient analysis. Despite comparable dry matter (DM) and caloric intakes between the two chicken-based diets, the fresh diet led to lower defecation frequency (1.2 ± 0.2 vs. 1.7 ± 0.5 times/d, adjusted P < 0.001), lower fecal DM (24 ± 8 vs. 47 ± 10 g/d, adjusted P < 0.001), and lower fecal calories (92 ± 31 vs. 189 ± 43 kcal/d, adjusted P < 0.001) than the kibble diet. The apparent total tract digestibility of DM, protein, fat, nitrogen-free extract, and calories of the kibble diet were all significantly lower than any of the fresh diets (adjusted P < 0.001 for all). Measured ME per food DM in all of the fresh diets, except the pork-based recipe, was significantly higher than that of the kibble diet (adjusted P < 0.001 for all). For the kibble diet, the modified Atwater calculation underestimated the ME and the NRC 2006 calculation was the most accurate predictor of ME. The standard Atwater calculation performed best for the two fresh diets that had the highest fat content (chicken, beef) and the NRC 2006 calculation performed best for the fresh diet that had the highest protein content (pork). ME of the turkey-based diet was equally overestimated and underestimated with the standard Atwater and NRC 2006 methods, respectively. We propose that commercial and home-prepared fresh diets should be assessed using standard Atwater factors as commonly done in human nutrition, or preferably for commercial products, by direct measurement in conforming feeding trials.

Determination of Nutrient Digestibility in Calves Supplemented with Various Levels of Corn Gluten Feed When Consuming Forage-based Rations

Abstract The experimental objective was to determine the effect of supplementing various levels of corn or corn gluten feed (CGF) on apparent total tract nutrient digestibility in cattle consuming a forage-based ration. Twelve purebred Angus and Simmental heifers were stratified across treatments by BW and breed in a 2x2 factorial arrangement across 2 periods (n = 6/treatment). Treatments included either corn or CGF supplemented at 0.25% BW or 0.75% BW with ad libitum access to alfalfa hay. Each period lasted 21 d, with animals housed as a group and moved to individual stalls to consume supplement each morning during the first 10 d and individually thereafter. Fresh alfalfa and supplement were provided daily throughout the experiment, and feed offered and refused were recorded daily while animals were housed individually. During the final 3 d of each period, fecal samples were obtained directly from the rectum of each animal every 6-h. Samples were analyzed for neutral detergent fiber (NDF), organic matter (OM), and crude protein (CP). Data were analyzed using lm in R with significance defined at P ≤ 0.05. The statistical model included the fixed effects of supplement type, level, and their interaction, breed, and period. No differences (P ≥ 0.28) in ADG or G:F were noted among treatments. Total tract NDF, ADF, and OM digestibility did not differ among treatments, but OM and ADF digestibility tended to be greater (P = 0.10 and P = 0.06, respectively) for animals supplemented with corn. Crude protein digestibility was not influenced by supplement type (P = 0.46), but tended to be greater (P = 0.07) for animals supplemented at 0.25% BW. These results indicate that at supplement levels below 0.75% BW, supplementing cattle with CGF does not result in an improvement in apparent total tract digestibility relative to corn under the conditions of this experiment.

Orange fibre effects on nutrient digestibility, fermentation products in faeces and digesta mean retention time in dogs

ABSTRACT Fermentable fibres are used in commercial dog food to promote intestinal health by providing substrates for better metabolic activity of the gut microbiota. Brazil is the world’s largest producer of oranges, from which it is possible to obtain fibre with a relevant soluble fraction. The present study compared the effects of two inclusions of orange fibre (1% and 3%, on as fed basis) with a negative control (without addition of fibre source) and two positive controls, beet pulp (3%) and purified inulin (1%), totalling five extruded diets for dogs. The experiment followed a randomised block design with 4 blocks of 10 dogs, 2 dogs per food in each block, totalling 8 dogs per diet. The apparent total tract nutrient digestibility was determined by total faecal collection. Faecal pH and fermentation product content were also measured. The digesta mean retention time (DMRT) was evaluated using plastic markers. The inclusion of a 3% fibre source in diets with 3% orange fibre and beet pulp reduced DM, OM, and energy digestibility (p < 0.05). Diets with 3% orange fibre, beet pulp and 1% inulin presented lower crude protein digestibility than the control (p < 0.05). Dietary fibre digestibility was higher for orange fibre-supplemented diets than inulin (p < 0.05). Beet pulp and 3% orange fibre inclusions resulted in increased moisture content in the faeces of dogs (p < 0.05) but did not alter DMRT. Total short-chain fatty acids were higher than the control in the faeces of dogs fed both orange fibre levels and the beet pulp-supplemented diet (p < 0.05), and the inulin diet-fed dogs presented intermediate values. Butyrate was higher in the faeces of dogs fed the diets supplemented with 1% and 3% orange fibre (p < 0.05), and similar values to the control were observed for beet pulp- and inulin-fed animals. Thus, it was concluded that orange fibre presented higher apparent total tract dietary fibre digestibility than beet pulp and had a fermentation profile in the colon that promoted the generation of butyrate, an effect not observed for inulin and beet pulp.

Effects of Rumen-Protected Niacin on Dry Matter Intake, Milk Production, Apparent Total Tract Digestibility, and Faecal Bacterial Community in Multiparous Holstein Dairy Cow during the Postpartum Period.

Simple SummaryThe main challenge faced by cows during the first three weeks after calving is the sudden increase in nutrient demand for milk production while dry matter intake and nutrient supply lag. Although metabolic hormone changes are a normal adaptive process in high yielding cows, failure to adapt to this challenge can lead to disease states and affect production and reproductive efficiency. Therefore, a smooth transition from prepartum to postpartum period for optimal dairy cow health and performance. Whether rumen-protected niacin supplementation could be a useful additive was controversial. This work tested whether the widespread use of rumen-protected niacin in multiparous Holstein dairy cows could be justified.Extensive studies about rumen-protected niacin (RPN) supplementation on dairy cows in early-lactation have been done, but the effects of RPN on changes in dry matter intake (DMI), milk production, feed digestibility, and fecal bacterial community were conflicting. The aim of this study was to investigate them affected by RPN in postpartum cows. Multiparous Holstein dairy cows (n = 12, parity = 3.5 ± 0.5, body weights = 740 ± 28 kg) were divided into two groups supplemented with either 0 (CON) or 20 g/d RPN (RPN). Our results showed that RPN supplementation increased DMI and milk production of cows during the first three weeks after calving (p < 0.05). The concentrations of neuropeptide Y and orexin A were significantly higher in RPN group than that in the CON group during postpartum period (p < 0.05). The apparent total-tract digestibility of nutrients was similar between the CON and RPN groups at 2 weeks after calving (p > 0.05). The 16S rRNA gene sequencing analysis showed that RPN had no impact on the alpha and beta diversity, although 4 genera were changed in cow feces at 14 days after calving. Overall, 20 g/d RPN added to the diet could improve DMI and milk yield up to two weeks after calving with little influence on feed digestibility.

Effect of xylanase and live yeast supplementation on growth performance, nutrient digestibility, and gut microbiome diversity of pigs

Effect of xylanase (Xyl) and live yeast (LY) supplementation on gut microbiome composition, growth performance, and nutrient digestibility of weanling pigs was determined. A total of 180 weanling pigs were assigned to five treatments from weaning to market. Treatments were designated based on whether Xyl, LY, or their combination were fed in the first 2 wk postweaning or thereafter until finishing at day 141 postweaning. Treatments were (days 1–15; days 15–141): control–control, control–Xyl, Xyl–Xyl, LY–Xyl, Xyl + LY–Xyl. Xylanase was added at 16 000 BXU·kg−1 and LY at 1 kg·t−1. Pigs fed with LY and LY + Xyl from days 0–15 had greater body weight and average daily gain at day 15 compared with control (P &lt; 0.05). Glucose transporter 2 mRNA was higher in LY and LY + Xyl groups on day 15 compared with control (P &lt; 0.05). Xylanase supplementation from week 2 postweaning increased apparent total tract nutrient digestibility of gross energy, nitrogen, and phosphorus on day 43. Live yeast with or without Xyl improved growth performance in the first 2 wk after weaning; Xyl + LY–Xyl and control–Xyl groups had improved overall feed efficiency. In conclusion, LY and Xyl supplementation improved performance of weanling pigs in the first 2 wk after weaning with no effects on long-term growth performance.

Effects of barley and corn as sources of silage and grain on dry matter intake, ruminal fermentation, and total-tract digestibility in growing beef heifers

The objective of this study was to evaluate the use of barley (BS) or corn (CS) silage when fed with dry-rolled barley grain (BG), corn grain (CG), or an equal blend (BCG) of BG and CG for backgrounding cattle. Ruminally cannulated heifers (n = 5) were assigned to an incomplete 6 × 6 Latin square design. Treatments contained either BS or CS in combination with BG, CG, or BCG. Samples were collected to determine dry matter intake, ruminal fermentation, total-tract nutrient digestibility, and nitrogen (N) balance. Interactions between cereal silage and cereal grain sources were detected for the molar proportions of propionate and butyrate where the magnitude of change with the type of cereal grain was increased in heifers fed CS relative to BS. Feeding CS increased estimated microbial N production (silage, P = 0.022) and fecal N excretion (silage, P = 0.042) over BS. Diets containing BG had greater dry matter, organic matter, starch, and gross energy digestibility values compared with CG, but values for BCG were not different (grain, P ≤ 0.043). Based on limited silage × grain interactions, use of CS in backgrounding diets may increase microbial N production relative to BS and dry-rolled CG may reduce apparent total-tract nutrient digestibility relative to dry-rolled BG.

Optimum grape pomace proportion in feedlot cattle diets: ruminal fermentation, total tract nutrient digestibility, nitrogen utilization, and blood metabolites.

Because of its high content of polyphenolic compounds, the dietary inclusion of grape pomace (GP) in ruminant diets can reduce reactive nitrogen (N) and methane emissions and enhance the shelf life and beneficial fatty acids (FAs) content of meat. However, the dietary inclusion of GP beyond a threshold that is still to be determined for feedlot cattle can also compromise nutrient supply and, thus, growth performance. This study investigated the optimum proportion of GP in finishing cattle diets. Nutrient intake and apparent total tract digestion, ruminal pH and fermentation, estimated microbial protein synthesis, route of N excretion, and blood metabolites were measured. Six ruminally fistulated crossbred beef heifers (mean initial body weight ± SD: 714 ± 50.7 kg) were used in a replicated 3 × 3 Latin square with 21-d periods. Dietary treatments were 0%, 15%, and 30% of dietary dry matter (DM) as GP, with diets containing 84%, 69%, and 54% dry-rolled barley grain, respectively. There was a linear increase (P = 0.07) in DM intake and quadratic change (P ≤ 0.01) in neutral detergent fiber (NDF) intake. There was a quadratic change (P ≤ 0.04) in apparent total tract DM, NDF, and crude protein digestibility as dietary GP content increased. However, there were no treatment effects (P ≥ 0.18) on total ruminal short-chain FA concentration and duration and area pH < 6.2, 5.8, and 5.5. Although N intake did not differ (269, 262, 253 g/d; P = 0.33) across dietary treatments, feeding GP led to a tendency for a quadratic change (P ≤ 0.07) in ruminal ammonia-N and plasma urea-N concentrations. Total N excretion also changed (quadratic, P = 0.03) because of changes (quadratic, P = 0.02) in fecal N excretion as urinary excretion of N and urea-N did not differ (P ≥ 0.15) across treatments. Feeding GP led to quadratic changes (P ≤ 0.01) in fecal excretion of fiber-bound N. Microbial N flow and apparent N retention also changed (quadratic, P ≤ 0.04) as dietary GP proportion increased. In conclusion, responses to dietary GP proportion were mostly quadratic with indications that nutrient supply as reflected by changes in apparent total tract nutrient digestibility, microbial N supply, and apparent N retention could be compromised beyond a 15% dietary inclusion level.

Methionine precursor effects on lactation performance of dairy cows fed raw or heated soybeans

Two experiments were conducted to evaluate the effect of isopropyl ester of 2-hydroxy-4-(methylthio) butanoic acid (HMBi) on lactation performance of dairy cows. Experiment 1 evaluated the effect of HMBi in diets with 15.3% crude protein (CP) and with different proportions of rumen-degradable and undegradable protein. Variation in rumen-degradable and undegradable protein was achieved by replacing raw with heated soybeans. Experiment 2 was an on-farm trial to evaluate HMBi with a large number of observations and using a farm-formulated diet (17.2% CP). In experiment 1, 20 Holsteins at 100 ± 41 d in milk were allocated to 5 replicated 4 × 4 Latin squares with 21-d periods. Treatments were formed by a 2 × 2 factorial arrangement of raw or heated soybeans with or without HMBi. Paper capsules with HMBi were orally administered twice daily to each cow. Dosage of HMBi was 7.6 g of digestible Met/cow per day. There was no interaction between soybean type and HMBi. Heat-treated soybeans increased the yields of milk, protein, fat, and lactose, and reduced urea N in milk and plasma (PUN) compared with raw soybeans. Rumen microbial yield, dry matter intake (DMI), and the total-tract apparent digestibility of nutrients did not differ between soybean types. There was no evidence for HMBi-driven effects on DMI, milk and components yield, or diet digestibility. Urinary purine derivative excretion and PUN concentration were reduced in HMBi-fed cows compared with cows fed diets without HMBi. In experiment 2, 294 Holstein cows were blocked by parity and milk yield, and randomly assigned to HMBi (8.9 g of digestible Met/cow per day) or control. The final data set had 234 cows (215 ± 105 days in milk; 96 primiparous and 138 multiparous; 114 on control and 120 on HMBi) housed in 4 freestall groups (1 group/treatment per parity). The freestall group was the experimental unit for DMI, diet and orts composition, and feed availability. The HMBi supplement was top dressed for 28 d on the first daily meal of each cow, immediately after feed delivery of the same batch of feed to all 4 freestall groups (3 times per day). Sample collection and feed analysis occurred during the last 5 d. Spot urine samples and blood samples from each cow were obtained for analysis of the urinary allantoin to creatinine ratio and PUN. Feed availability, the contents of CP and neutral detergent fiber in diets and orts, and DMI did not differ. Cows fed with HMBi had greater milk protein yield and concentration compared with control and had no change in milk fat and lactose. Rumen microbial yield was greater and PUN was lower in HMBi-fed cows compared with control. In experiment 1, HMBi decreased rumen microbial yield and did not affect lactation performance, but it increased ruminal microbial yield and the secretion of milk protein in experiment 2. These results suggest that lactation response to HMBi may be partially mediated by ruminal events. Heated soybeans increased the efficiency of N utilization and the yields of milk, protein, fat, and lactose, but did not interact with HMBi supplementation.

Effects of dietary supplementation with fermented Chenopodium album L. on growth, nutrient digestibility, immunity, carcase characteristics and meat quality of broilers

Here, we investigated the effects of fermented Chenopodium album L. (FCAL) on growth performance, apparent total tract nutrient digestibility, serum immunity, carcase characteristics and meat quality of broilers. Arbour Acres broilers (160, 1-d-old) were randomly allocated into four treatment groups with five replicates of eight birds each. The birds were fed a corn–soybean meal basal diet supplemented with 0 (control [CON]), 2, 4 and 8 g/kg FCAL. During the starter period (days 1–21), 4 and 8 g/kg FCAL significantly increased the average daily gain (ADG), apparent digestibility of dry matter (DM), crude protein (CP) and ether extract (EE), moreover; 8 g/kg FCAL significantly decreased the feed conversion ratio (FCR). During the finisher period (days 22–42), 2 g/kg FCAL significantly increased ADG and apparent digestibility of DM, CP and EE but significantly decreased FCR. During the whole period (days 1–42), dietary supplementation of 4 and 8 g/kg FCAL significantly increased ADG. Compared with the CON group, in the FCAL groups, the serum interleukin (IL)-1β and IL-8 levels were lower, while insulin-like growth factor-1, immunoglobulin (Ig) A (IgA) and IgM levels were higher. The serum IL-10 content was lower in the 2 and 4 g/kg FCAL groups. The breast muscle percentage significantly increased with 8 g/kg FCAL. FCAL significantly decreased muscle drip loss (breast), shear force (breast), water loss rate and lightness (leg). FCAL had positive effects on growth, nutrient digestibility, immunity, carcase characteristics and meat quality of broilers, thus it could be a reliable and phytogenic feed additive for promoting growth and maintaining health of broilers. Highlights Fermented Chenopodium album L. (FCAL) can improve growth performance and apparent nutrient digestibility of broilers. FCAL can promote immune responses and enhance carcase characteristics and meat quality of broilers. FCAL could be a reliable and potential phytogenic feed additive to promote growth and maintain the health of broilers.

Effects of corn particle size on energy and nutrient digestibility in diets fed to young pigs and adult sows.

ObjectiveThis research was carried out to investigate the effects of corn particle size on the apparent total tract digestibility (ATTD) of energy and nutrients fed to pigs at four different growth stages and therefore to provide basis for better application of corn in pig feeds.MethodsEighteen weanling piglets, 18 growing barrows, 24 gestating sows and 24 lactating sows were used in this study. Within each stage, pigs were allotted to 1 of 3 or 4 corn-soybean meal diets which were formulated with different corn particle size in a completely randomized design with 6 replicate pigs per diet. Each stage lasted for 19 days, including 7 days for cages adaptation, 7 days for adaptation to diets and followed by 5 days for total collection of feces and urine.ResultsFor nursery and growing stages, the results showed that digestible energy content and ATTD of gross energy (GE), dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) was increased (p<0.05) as the corn particle size reduced. Meanwhile, the metabolizable energy content and ATTD of crude protein (CP) tended to increase. For gestating sows, no differences were found in the ATTD of nutrients among dietary treatments. As for lactating sows, there were linear and quadratic increases (p<0.05) in the ATTD of DM, GE, NDF as the corn being finer milled. Quadratic response in ATTD of ADF and CP (p<0.05) were observed as sows fed with four different diets.ConclusionReducing corn particle size can increase digestibility of nutrients fed to young pigs and lactating sows. No effects were observed in present experiment when gestating sows were fed with different particle sized corn.

Replacing soybean meal with okara meal: Effects on production, milk fatty acid and plasma amino acid profile, and nutrient utilization in dairy cows

Okara meal is a byproduct from the production of soymilk and tofu and can potentially replace soybean meal (SBM) in dairy diets due to its high crude protein (CP) concentration and residual fat. The objective of this study was to investigate the effects of replacing SBM with okara meal on feed intake, yields of milk and milk components, milk fatty acid (FA) profile, nutrient utilization, and plasma AA concentration in lactating dairy cows. Twelve multiparous (65 ± 33 d in milk) and 8 primiparous (100 ± 35 d in milk) organically certified Jersey cows were paired by parity or days in milk, and within pair, randomly assigned to treatments in a crossover design with 21-d periods (14 d for diet adaptation and 7 d for data and sample collection). Diets were fed as total mixed ration formulated to be isonitrogenous and isofibrous and contained (dry matter basis) 50% mixed, mostly grass baleage, 2% sugarcane liquid molasses, 2% minerals-vitamins premix, and either (1) 8.1% SBM, 10% soyhulls, and 27.9% ground corn (CTRL); or (2) 15% okara meal, 8% soyhulls, and 23% ground corn (OKR). Dietary CP, ash-free neutral detergent fiber, and total FA averaged 15.4, 35.3, and 3.08% for CTRL and 15.9%, 36.3%, and 3.74% for OKR, respectively. Substitution of SBM with okara meal did not alter dry matter intake but increased intakes of CP and ash-free neutral detergent fiber. Additionally, no significant differences between treatments were observed for yields of milk and milk components, and concentrations of milk fat, lactose, and total solids. However, milk true protein concentration was lower in cows fed OKR (3.76%) versus CTRL (3.81%). Both milk urea N (8.51 vs. 9.47 mg/dL) and plasma urea N (16.9 vs. 17.8 mg/dL) concentrations decreased with OKR relative to the CTRL diet, respectively. Compared with CTRL, feeding OKR lowered the milk proportions of total odd-chain FA, de novo FA, and mixed FA and increased those of preformed FA, total n-6 FA, and total n-3 FA. The milk proportions of trans-10 18:1, trans-11 18:1, and cis-9,trans-11 18:2 were greater with feeding OKR versus the CTRL diet. The apparent total-tract digestibility of nutrients, urinary excretion of total purine derivatives (uric acid plus allantoin), and total N were not affected by treatments. Except for plasma Leu, which was lower in OKR compared with the CTRL diet, no other significant changes in the plasma concentrations of AA were observed. The plasma concentration of carnosine was lowest in cows receiving the OKR diet. Overall, our results revealed that okara meal can completely replace SBM without negatively affecting production and nutrient digestibility in early- to mid-lactation Jersey cows. Further research is needed to assess the economic feasibility of including okara meal in dairy diets, as well as the amount of okara meal that maximizes yields of milk and milk components in dairy cows in different stages of lactation.

Effect of storage of wet brewer's grains with incremental levels of salt on apparent total tract nutrient digestibility and purine derivative excretion in dairy heifers.

Objectives of this study were to evaluate apparent total tract nutrient digestibility and purine derivative (PD) excretion in dairy heifers limit-fed diets containing wet brewer's grains (WBG) treated with salt. A 12-wk replicated 4 × 4 Latin square was conducted using 8 Holstein heifers of 224.5 ± 19.4 d of age, and body weight (BW) of 219.2 ± 28.1 kg (mean ± SD). Fresh WBG were treated with 0%, 0.8%, 1.6%, and 2.4% salt and stored for 4 d before being fed. Salt was added either to the WBG or separately to equalize the amount of salt in the diet. The diet contained 9% grass silage, 47% corn silage, 19% corn meal, 17.6% WBG and salt, 2% soybean meal, and 3% mineral mix. Diets were formulated to be limit-fed at 2.15% of BW, provide 14% crude protein (CP) and 2.27 Mcal metabolizable energy (ME)/kg of dry matter (DM). Heifers were adapted to diets for 14 d followed by a 7-d collection period. Dry matter intake (DMI) was recorded daily during the collection week while BW was recorded once a week. Urine and fecal samples were collected during the last 4 d of the collection period. Acid insoluble ash was used as an internal marker to determine apparent nutrient digestibility. Weight loss of WBG during storage was determined from days 1 to 11 and initial and final yeast and mold counts were determined. Final yeast counts were similar among treatments while final mold counts tended to be lesser (P = 0.07) for the 0.8% and 1.6% salt treatments. Urinary volume was similar among treatments while allantoin (P = 0.14), and uric acid (P < 0.01) and total PD excretion tended to increase (P = 0.13) quadratically. DMI was varied by treatment (linear, quadratic, and cubic effects P < 0.01). Heifers fed the 0.8% treatment had the least DMI. Nonfiber carbohydrate (NFC) digestibility linearly decreased (P < 0.04) as salt increased. Digestibilities of DM, and organic matter (OM), tended to decrease (P < 0.10) with increasing levels of salt added to WBG. Fat digestibility was quadratic with the greatest value for the 1.6% treatment. Treating WBG with salt reduced its deterioration based on lesser mold counts for the 0.8% and 1.6% treatments. These treatments had resulted in greater fat digestibility and tended to have increased PD excretion suggesting improved microbial protein synthesis.

86 Apparent Total Tract Nutrient Digestibility of Human-Grade Dog Foods and Their Effects on Stool Characteristics, Serum Metabolites, and Hematology of Dogs

Abstract Human-grade pet foods are believed to be of higher quality than traditional pet foods, but little research has been conducted on them to date. Therefore, our objective was to determine the apparent total tract digestibility (ATTD) of human-grade pet foods and evaluate their effects on stool characteristics, serum metabolites, and hematology of dogs. Twelve dogs (mean age = 5.5 ± 1.0; BW = 11.6 ± 1.6 kg) were used in a replicated 4×4 Latin square design. The diets included: 1) Chicken and Brown Rice Recipe (extruded; Blue Buffalo); 2) Roasted Meals Tender Chicken Recipe (fresh; Freshpet); 3) Beef &amp; Russet Potato (human-grade; JustFoodForDogs); and 4) Chicken &amp; White Rice (human-grade; JustFoodForDogs). Each period consisted of 28 d, with a 6-d diet transition phase, 16 d of consuming 100% of the diet, a 5-d phase for total and fresh fecal collection, and 1 d for blood collection. All data were analyzed using the Mixed Models procedure of SAS 9.4. Dogs fed the extruded diet had a higher (P &amp;lt; 0.05) daily food intake (dry matter basis; DMB) and fecal output (as-is and DMB) compared with dogs fed fresh or human-grade dog foods. There were no differences in fecal pH or scores across diets, but ATTD of dry matter (DM), organic matter (OM), and acid-hydrolyzed fat (AHF) were greater (P &amp;lt; 0.05) for dogs fed the human-grade diets than those fed the fresh diet. Likewise, DM, OM, and AHF ATTD were greater (P &amp;lt; 0.05) in dogs fed the fresh diet than those fed the extruded diet. The majority of serum metabolites and blood cell counts of dogs fed all diets were within the reference ranges for adult dogs, with few treatment differences. In conclusion, the human-grade foods tested were shown to be highly digestible and maintained stool characteristics, serum chemistry, and complete blood count in adult dogs.

PSII-17 Comparison of corn ethanol co-products from Brazil and USA apparent total tract digestibility of nutrients in pigs

Abstract The objective of this study was to determine the apparent total tract digestibility (ATTD) of DM, GE, EE, NDF, ADF, and CP, the metabolizability of energy, of two high protein (HP) corn distillers dried grain (DDG) and of two corn DDG with solubles (DDGS), from Brazil and USA, and their respective digestible and metabolizable energy content in growing pigs. Fifty crossbred barrows (32.4±6.9kg) were distributed in a randomized block design, with 10 replicates, and received a 96.7 % corn basal diet (BD) or four diets with 40% of each test ingredient: Brazilian HP DDG (BHP); USA HP DDG (UHP); Brazilian DDGS (BDG) and USA DDGS (UDG), substituting for corn. Animals were fed at 2.8 x maintenance (110 kcal of DE per kg of BW0.75) for 7 d adaptation and 4 d of total feces and urine collection. The ATTD of nutrients and energy were calculated by difference and the results were submitted to ANOVA and Tukey’s test (P&amp;lt; 0.05). The BHP and UHP samples contained (as is basis) 92.3 – 89.6% DM, 2.8 – 3.5% ash, 42.9 – 34.9% CP, 10.3 – 7.3% EE, 32.7 – 47.5% NDF, 13.3 – 17.5% ADF, 5.30 – 4.90 Mcal/kg, respectively. The BDG and UDG samples contained (as is basis) 86.1 – 86.1% DM, 4.8 – 4.9% ash, 13.9 – 25.8% CP, 9.0 – 6.4% EE, 40.8 – 40.2% NDF, 13.3 – 14.3% ADF, 4.51 – 4.53 Mcal/kg, respectively. The ATTD of DM and GE and the digestible and metabolizable energy contents of BHP were greater (P&amp;lt; 0.05) than those verified in UHP. The ATTD of DM, GE, NDF, ADF, digestible and metabolizable energy values of BDG were lower (P &amp;lt; 0.05) than those verified in UDG. In conclusion, the BHP presented higher digestible values to almost all parameters evaluated, however, all ingredients presented acceptable digestible contents, indicating they may be used in pigs feeding.

PSVI-3 Effects of dietary supplementation of multi-species direct-fed microbial products on energy status, apparent nutrient digestibility, and rumen metatranscriptome of beef steers

Abstract This study evaluated the effects of two different multi-strain direct-fed microbial products on energy status, nutrient digestibility, and ruminal metatranscriptome of beef steers. Nine rumen-cannulated Holstein steers were assigned to 3 treatments arranged in a 3 × 3 Latin square design with three 21-d periods. Dietary treatments were (1) CON (basal diet without additive), (2) PROB (basal diet plus 19 g/d of Commence), and (3) SYNB (basal diet plus 28 g/d of RX3). Commence is a blend of S. cerevisiae, Enterococcus lactis, Bacillus subtilis, Enterococcus faecium, and L. casei. RX3 is a blend of S. cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and Bacillus subtilis. Rumen fluid (for metatranscriptomics analysis) and blood samples (for analysis of plasma glucose and non-esterified fatty acid) were collected on d 21 of each period. From d 16 – 20, TMR and fecal samples were collected daily to determine apparent total tract digestibility of nutrients using indigestible neutral detergent fiber (iNDF) method. The data were analyzed using the GLIMMIX procedure of SAS. The model included the effects of treatment, period, and random effects of cow and square. There were no effects on DMI and non-esterified fatty acid. Compared with CON, steers fed either additives had greater (P = 0.02) plasma glucose concentrations. Results of metatranscriptome analysis revealed no differentially expressed functional genes among the treatments. Apparent total-tract digestibility of nutrients were also similar among treatments. These results demonstrated that supplemental PROB and SYNB improved the plasma glucose concentration, but had no effects on the functional capacity of the ruminal microbiome and apparent digestibility of nutrients in beef steers.

Diet supplementation with thyme oil and its main component thymol failed to favorably alter rumen fermentation, improve nutrient utilization, or enhance milk production in dairy cows

Phenolic compounds and essential oils with high content of phenolic compounds have been reported to exert antimicrobial activities in vitro. The objective of this study was to determine the effects of dairy cow diet supplementation with thyme oil and its main component thymol on intake and total-tract apparent digestibility of nutrients, rumen fermentation characteristics, ruminal protozoa, nitrogen excretion, and milk production. For this aim, we used 8 multiparous, ruminally cannulated Holstein cows in a replicated 4 × 4 Latin square design (28 d periods), balanced for residual effects. Cows were fed 1 of the 4 following experimental treatments: total mixed ration (TMR) with no additive (control); TMR + monensin [24 mg/kg of dry matter (DM)]; TMR + thyme oil (50 mg/kg of DM); and TMR + thymol (50 mg/kg of DM). Compared with the control diet, feeding thyme oil or thymol had no effect on DM intake, nutrient total-tract apparent digestibility, total N excretion, ruminal pH, ammonia concentration, total volatile fatty acid (VFA) concentration, or acetate:propionate ratio. Ruminal protozoa density was not modified by thyme oil, but decreased with thymol supplementation. Supplementation with thyme oil or thymol did not affect milk production, milk composition, or efficiency of milk production. Neither thyme oil nor thymol affected efficiency of dietary N use for milk N secretion (N intake/milk N). Supplementation with monensin tended to decrease DM intake (-1.2 kg/d) and milk fat yield. Total-tract apparent digestibility of nutrients did not differ between cows fed monensin and cows fed the control diet. Total VFA concentration was not changed by monensin supplementation compared with control, but adding monensin shifted the VFA profile toward more propionate and less acetate, resulting in a decrease of acetate:propionate ratio. Protozoa density and ammonia concentration were lower in the ruminal content of cows fed monensin compared with that of cows fed the control diet. Total N excretion was not affected by monensin supplementation. Likewise, efficiency of use of dietary N for milk N secretion was unchanged in cows fed monensin. The results of this study contrasted with the claimed in vitro antimicrobial activity of thyme oil and thymol: we observed no positive effects on rumen metabolism (i.e., N and VFA) or milk performance in dairy cows. Under the conditions of this study, including thyme oil or thymol at 50 mg/kg of DM had no benefits for rumen fermentation, nutrient utilization and milk performance in dairy cows.

Sodium butyrate and monensin supplementation to postweaning heifer diets: Effects on growth performance, nutrient digestibility, and health

The objective of this study was to evaluate growth and performance of postweaning heifers supplemented with monensin (MON), sodium butyrate (SB), or the combination of MON and SB (MSB) compared with heifers not receiving these feed additives. Forty Holstein heifers [mean age 84.2 ± 1.2 d; body weight (BW) 99.8 ± 10.8 kg (mean ± SD)] were housed in a freestall barn, blocked by birth date, and randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments were (1) 100 g of soybean meal carrier (control; CON); (2) 0.75 g of SB/kg of BW + carrier (SB); (3) 1 mg of MON/kg of BW + carrier (MON); (4) 1 mg of MON/kg of BW + 0.75 g of SB/kg of BW (MSB). Data were analyzed using single degree of freedom contrasts evaluating CON versus additives (ADD), SB versus MON, and SB and MON versus MSB. Treatments were hand-mixed daily. Feed and orts were measured daily and frozen at -20°C. Orts samples were subsampled for dry matter (DM) determination, and total mixed ration samples were taken weekly and composited monthly for DM and nutrient analysis. Initial BW, heart and paunch girths, body length, blood samples, and fecal coccidia counts were measured before the start and weekly during the 12-wk trial. Blood samples were analyzed for glucose, plasma urea nitrogen (PUN), and ketone concentrations. Apparent total-tract nutrient digestibility was determined from d 21 to 27 and from d 63 to 69 using acid detergent insoluble ash as a marker. Daily dry matter intake (DMI) and metabolizable energy intake were increased in ADD compared with CON, and average BW, final BW, and heart girth tended to increase. Whereas MSB tended to be greater than SB and MON for heart girth, feed efficiency was greater with MON compared with SB. Compared with CON, ADD decreased coccidia counts. No effect of treatment on PUN was detected. Monensin and SB tended to have greater plasma glucose than MSB did. Average blood ketone concentrations were greater with ADD versus CON, in SB versus MON, and in MSB versus SB and MON. During the wk-3 digestibility phase, DMI tended to be greater in heifers fed SB versus MON, as well as in heifers fed MSB versus SB and MON. Digestibility of nutrients were similar, except that starch digestibility was increased in heifers fed MSB versus SB and MON. During the wk-9 digestibility phase, DMI and digestibility of nutrients were similar, except NDF, which tended to be greater in CON than in ADD. Overall, ADD resulted in positive growth and reduced coccidia compared with CON.

Effect of forage source and dietary rumen-undegradable protein on nutrient use and growth in dairy heifers

Thirty-two Holstein heifers with mean (± standard error of the mean) age of 6.5 months (±0.12) and live weight (LW) of 166 kg (±1.6) were divided into four groups of eight animals to evaluate the effect of forage source and the concentrations of rumen-undegradable crude protein (RUP) in the diet with a 2 × 2 factorial design. As forage sources cowpea hay (Vigna sinensis L.) or pangola grass hay (Digitaria decumbens Stend) were added to the diet at 250 g/kg dry matter (DM). Also, 350 g/kg DM of chopped fresh King grass (Pennisetum purpureum Schum.) was included in all diets. The RUP proportions were 260 or 360 g/kg of total crude protein (CP). Heifers were housed in metabolism cages. The trial lasted ten weeks, with the first two weeks used for adaptation and the last week for data collection and sampling. Diets had a forage to concentrate ratio of 60:40 (on DM basis), and were offered as total mixed rations ad libitum. Fish meal or urea were used to produce varying concentrations of RUP at similar dietary CP content. Diet ingredients (i.e., hay, grass, and concentrate) and feces were sampled for nutrient analysis. Total collection of feces was performed to estimate apparent total tract nutrient digestibility (ATTD). Urinary purine derivative excretions were determined from urine spot samples to estimate rumen microbial protein synthesis. The effects of forage source, RUP, and its interactions were determined by general linear model analysis. Replacing dietary pangola grass hay with cowpea hay increased daily intakes of DM, organic matter, CP, acid detergent fiber (ADF), and digestible organic matter, and ATTD of DM, organic matter, neutral detergent fiber, and ADF (P < 0.05). Duodenal flow of RUP also increased when substituting cowpea hay for pangola grass hay (P < 0.01). Similarly, inclusion of cowpea hay in the diet improved live weight gain (LWG; P < 0.05), and decreased feed costs per kg of LWG (P < 0.01). The increase in RUP decreased rumen microbial protein synthesis (P < 0.01), but tended to increase LWG, feed conversion and nitrogen use efficiency, and feed costs per unit of LWG (P < 0.10). The use of cowpea hay in the diet of dairy heifers increases nutrient intake and ATTD, leading to improved LWG and lower feed costs per kilogram of LWG. Increasing RUP proportions may reduce rumen microbial protein synthesis, but may enhance LWG, feed conversion efficiency, and nitrogen use efficiency. There were no interactions between forage source and RUP proportion on intake and ATTD, but some synergistic effects were observed for the performance parameters.

Interactive effects between sugar source and pelleting temperature on processing, digestibility and blood metabolites in nursery piglets

The aim of this study was to evaluate the effect of pelleting temperature (60°C or 90°C) and the type of sugar source (refined sugar cane or sugar cane molasses), on post-processed diet characteristics and on animal body weight gain, apparent total tract digestibility of energy and nutrient, and blood metabolites. Thirty-two recently-weaned piglets of both sexes were randomly assigned to 1 of the 4 treatments in a 2 (sugar source, refined sugar cane or sugar cane molasses) x 2 (pelleting temperature, 60°C or 90°C) factorial arrangement. The physicochemical characteristics of the diets evaluated were pellet durability index, fine content and starch gelatinization index. After seven days of adaptation, partial fecal samples were collected for apparent digestibility analyses for five days. For weight gain evaluation, the animals were weighed at 28, 35, 40 and 63 days of age. Blood samples were collected at the beginning (28 days) and the end of the experiment (63 days). Data were submitted to variance analysis and the means were compared by the Tukey test. There was interaction between pelleting temperature and sugar source on the pellet durability index, on the fine content and on the starch gelatinization index (P < 0.05) of the diets. Pelletizing at 90°C increased the pellet durability index in treatment with sugar cane molasses. The fine content was reduced in treatments with pelleting temperature at 90°C and increased in treatments with sugar cane molasses. There was an increase of the starch gelatinization index with refined sugar cane at 90°C. There was no interaction between pelleting temperature and sugar source on starch composition of the diets. The pelleting temperature and the type of sugar source did not influence the levels of resistant and non-resistant starch (P > 0.05). The total starch index was higher in treatments using sugar cane molasses. There was no interaction between pelleting temperature and sugar source on nutrient apparent total tract digestibility. The use of sugar cane molasses promoted higher apparent digestibility of gross energy and ash (A), and pelleting at 90°C increased the apparent digestibility of Ca, P and A (P < 0.05). There was interaction between pelleting temperature and sugar source on the gamma-glutamyltransferase (GGT) enzyme (P < 0.05), where the use of sugar cane molasses reduced GGT levels in the pelleted diet at 60°C. There was no effect of pelleting temperature and the type of sugar source on animal body weight gain, high density cholesterol (HDL), total cholesterol, triglycerides, urea and albumin. Therefore, sugar cane molasses can replace refined sugar cane as the palatable ingredient in the diet of nursery piglets without affecting animal body weight gain and levels of blood metabolites of the animals, promoting greater apparent digestibility of gross energy and ash, although it had altered the physicochemical characteristics of the diet. The use of sugar cane molasses allowed for the exploration of higher pelleting temperatures (90°C) in the feed processing, leading to increasing the apparent digestibility of Ca, P and A of the diets.