Maintenance Energy Requirements Research Articles

Estimation of genetic parameters for maintenance energy requirements and residual feed intake in Nellore cattle.

We estimated heritabilities and genetic and phenotypic correlation estimates for maintenance energy requirements (NEmR), residual feed intake (RFI), growth, carcass and reproductive indicator traits, using data from 41 feed efficiency trials in Brazil, comprising 4381 males and females. Continuous traits were analysed using a linear animal model and threshold traits were analysed using a threshold animal model. The heritability estimates were low for RFI (0.190) and NEmR (0.193); other heritabilities were mainly moderate (growth and carcass traits) or high (sexual precocity traits). The genetic correlation of RFI with NEmR was high (0.701). The genetic correlations of NEmR were low with carcass and reproductive traits, and moderate with growth traits. Thus, selection to improve weaning weight and female sexual precocity indicator traits would not affect maintenance energy requirement. Genetic selection to reduce maintenance energy requirements is feasible and would also reduce DMI and RFI. Selection to improve RFI can be used to identify animals with lower maintenance energy requirements. Long-term selection to reduce RFI and NEmR would have favourable effects on yearling weight, carcass muscle indicator traits and female sexual precocity. Genetic (co)variance component estimates for NEmR, in conjunction with economic values of selection criteria, may be used to develop novel approaches for genetic selection to improve efficiency of beef production.

Life cycle assessment of the production of an extruded dog food in Brazil

Sustainability is the current focus of the scientific community, governments, and companies in various market segments, such as pet food. Pet food production has increased rapidly in recent years, with a trend toward the development of environmentally friendly products and processes. The first step in creating strategies for mitigating environmental impacts is to assess key points in manufacturing processes. Given this, this study aimed to perform a life cycle assessment (LCA) to estimate the environmental impacts associated with the formulation, production, and distribution phases of an extruded dog food produced in Brazil. System boundaries were from cradle-to-gate, encompassing extraction of raw materials, transportation, processing, production, packaging, and distribution. Estimates were based on the amount of food required to meet the energy requirements for maintenance of a 10 kg dog (functional unit = 2.59 MJ day−1, reference flow = 177.3 g day−1). Environmental impacts were calculated by the environmental footprint method (EF 3.0 v. 1.00) using SimaPro software (v. 9.1.1.1). Product ingredients and packaging materials were modeled under Brazilian conditions using ecoinvent 3.7.1 and Agri-footprint 5.0 databases. Data regarding transportation, processing, distribution, electric and thermal power generation, water usage, and waste generation were obtained from the company's records (2019–2020). In this study, as expected, formulation was the most relevant factor, accounting for 70%–90% of the total environmental impacts. The main impact categories were terrestrial and marine eutrophication, acidification, particulate matter, and climate change (80% of total impacts). Production of the evaluated dog food was associated with the emission of 88.73 kg CO2 eq year−1 or 1.37 kg CO2 eq kg−1 distributed food. The use of animal meals (poultry by-product meal and meat and bone meal) and vegetable by-products (wheat bran and rice bran) contributed to reducing environmental impacts. Therefore, in this study, ingredient selection was considered the most important factor in mitigating the environmental impacts of pet foods. As the overall impact of the formulation depends on data on the use stage, such as nutrient excretion after consumption, future studies should adopt a cradle-to-grave approach for a better comprehension of the feasibility of applying animal and vegetable by-products in the eco-design of pet food products.

PSI-18 Effects of heat treatment and multi-carbohydrase supplementation on the digestibility of phosphorus in field peas fed to growing pigs

Abstract Most plant-based feed ingredients contain about two-thirds of their total P as phytate. Mineral elements are chelated to phytate or entrapped in plant cell walls, and microbial or enzymatic breakdown of cell walls may be able to release entrapped P, thus leading to improvement of the apparent total tract digestibility (ATTD) of P in pigs. Heat treatment is one of the processing methods that improve the digestibility of fiber in various feedstuffs for pigs. Therefore, this study aimed to determine the effects of heat treatment and multi-carbohydrase supplementation on the ATTD and standardized total tract digestibility (STTD) of P in peas fed to growing pigs. A total of 18 pigs (23.9 ± 1.3 kg) were assigned to 1 of 3 diets in a completely randomized design to give 6 replicates per diet. Three experimental diets were formulated: 1) non-heated or 2) heat-treated (pelleted) peas as the sole source of P, and 3) heat-treated peas with multi-carbohydrase supplementation. Pigs were individually housed in metabolism crates for 12 d, including 7 d for adaptation and 5 d for total collection of feces. Pigs were offered their daily ration at 2.8 times their maintenance energy requirement. Samples of ingredients, diets, and feces were analyzed for dry matter, Ca, and P. Fecal samples were analyzed for mixed bacterial mass (MBM) and volatile fatty acids (VFA) concentrations. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and replicate as random effect. An alpha level of 0.05 was used to determine statistical significance and P ≤ 0.10 was considered a trend. Pigs fed the diet that contained heat-treated peas with carbohydrase supplementation tended to have greater (P < 0.10) ATTD and STTD of P than pigs fed the diet containing heat-treated peas without enzyme. The values of STTD of P were 54.4, 47.3, and 55.0% for diets containing raw peas, heat-treated peas, and heat-treated peas with carbohydrase supplementation, respectively. Heat treatment and enzyme supplementation did not affect the ATTD of Ca in peas fed to growing pigs. No significant differences were observed in fecal MBM-P and VFA concentrations. In conclusion, carbohydrase supplementation tended to increase the digestibility of P in heat-treated peas fed to growing pigs, however, there was no difference in P digestibility between raw and heat-treated peas. Heat treatment and carbohydrase supplementation did not affect fecal MBM-P and VFA concentrations in growing pigs.

PSIV-A-4 Effect of late gestational nutrient restriction on locomotor activity of beef heifers

Abstract The objective of this study was to determine the effects of nutrient restriction on locomotor behavior during late gestation. Fall-calving crossbred beef heifers were moved to 3.7 × 15.8 m partially-covered pens and individually-fed 100% (control; n = 13) or 70% (nutrient restricted; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Diets were based on chopped sorghum sudan hay fed in Calan gates and supplemented to meet targeted nutritional planes. IceQube accelerometers (iceRobotics, Edinburgh, UK) were placed on the left hind fetlock between d 158 and 168 of gestation to determine standing time, lying time, step count, number of lying bouts, and motion index. Daily behavior data were averaged for 5 distinct periods (period 1: IceQube placement to d 180 of gestation; period 2: d 181 to 201 of gestation; period 3: d 202 to 222 of gestation; period 4: d 223 to 243 of gestation; and period 5: 244 to 264 of gestation). Days in which animals were moved from their pens were excluded from the data set, resulting in an average of 17.2 ± 2.35 d per period. Data were analyzed with fixed effects of nutritional plane, period, and their interaction in the model. Maternal sire and day of treatment initiation were included as covariates. The number of lying bouts was affected (P = 0.02) by the nutritional plane × period interaction. Within period, there was no effect (P ≥ 0.20) of nutritional plane on lying bouts. Lying bouts in control heifers decreased (P = 0.008) from period 1 to 2, whereas lying bouts in nutrient restricted heifers decreased (P = 0.002) from period 1 to 2 before increasing (P = 0.02) again from period 2 to 3. Motion index and step count were affected (P ≤ 0.05) by nutritional plane, where both were greater in control heifers. Motion index and step count were affected (P < 0.001) by period, while standing time and lying time tended to be affected (P ≤ 0.09) by period. Motion index and step count decreased (P < 0.001) between periods 1 and 2 and periods 3 and 4 but increased (P ≤ 0.004) between periods 2 and 3 and periods 4 and 5. Standing time decreased (P = 0.02), while lying time increased (P = 0.02), between periods 3 and 4. These data suggest that nutrient restricted heifers may have reduced locomotor behavior in late gestation compared with control heifers. Throughout all periods of gestation, control heifers took more daily steps and had a greater motion index, suggesting that nutrient availability in late gestation may directly impact locomotor behavior of beef heifers.

PSIV-A-7 Effects of late gestational nutrient restriction of beef heifers on small intestinal crypt depth in neonatal calves

Abstract We hypothesized that late gestational nutrient restriction would impair small intestinal development in neonatal calves, including crypt cell depth and proliferation. Fall-calving crossbred beef heifers [body weight (BW) = 466 ± 30 (SD) kg; BCS: 5.4 ± 0.5] bred to a single sire were individually-fed 100% (control; n = 10) or 70% (nutrient restricted; n = 12) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Calves were removed from their dams immediately post-calving and fed artificial colostrum and milk replacer relative to body weight until euthanasia at 48.7 ± 0.4 h of age. The gastrointestinal tract was removed, and proximal jejunum samples were dissected from each calf and immersion-fixed in 10% neutral buffered formalin. Tissues were embedded in paraffin blocks and cut into 5-µm sections that were mounted on glass slides. Slides were incubated with Ki-67 (marker of nuclear proliferation) and counterstained with Hematoxylin using an autostainer. Images were taken at 5× magnification using an upright microscope. QuPath software was used to measure crypt depth, starting at the base of the crypt region and ending at the furthest cluster of Ki-67 positive cells, perpendicular to the base of the mucosa. For each calf, 10 crypt depth measurements were taken from 4 images, resulting in 40 crypt depth measurements that were averaged. Nutritional plane was a fixed effect in the model, and maternal sire, date of study initiation, and calf sex (when P < 0.25) were considered covariates. We previously reported that calves born to nutrient restricted dams weighed less (P ≤ 0.05) at birth and 48 h than calves born to control dams. Small intestinal mass tended to be less (P = 0.11) in offspring of nutrient restricted dams but was not affected (P = 0.58) when expressed relative to body weight. Calves born to nutrient restricted dams also tended to have less (P = 0.11) small intestinal mass relative to brain weight. Maternal nutrient restriction did not affect (P = 0.95) jejunal crypt depth. Additionally, crypt depth relative to body weight was not affected (P = 0.20) by nutrient restriction. Although crypt depth was not affected, further analysis of proliferation and morphology will help to understand the relationship between maternal nutrient restriction and small intestine development in neonatal calves.

263 Effects of source of calcium carbonate and microbial phytase on standardized total tract digestibility of calcium by growing pigs

Abstract The objective of this experiment was to test the hypothesis that there are differences in the standardized total tract digestibility (STTD) of Ca and in response to microbial phytase among sources of calcium carbonate obtained from different regions of the world. Barrows [n = 320; average body weight (BW) = 17.47 kg; SD = 1.28] were allotted to 40 diets using a completely randomized block design with eight blocks of 40 pigs for a total of eight replicate pigs per diet. All diets were based on corn and potato protein concentrate. Twenty sources of calcium carbonate were obtained from different regions of the world, including the United States, Europe, Asia, and South Africa. Each source of calcium carbonate was used in two diets, one diet without microbial phytase and one diet that contained 1,000 phytase units/kg diet. Pigs were housed individually in metabolism crates. Pigs were provided feed at 3.0 times the maintenance requirement for energy. Feces were collected for 4 d following the adaptation period after 5 d of adaptation. Fecal samples were dried, ground, and analyzed for Ca to calculate the digestibility. The initial statistical model included calcium carbonate source, phytase, and the Ca-source × phytase interaction as fixed effects; however, no interactions between Ca source and phytase were observed. Therefore, the final statistical model included only Ca source and phytase as fixed effects. A second analysis was performed to compare the digestibility of Ca in calcium carbonate obtained from different regions of the world (i.e., Europe, Asia, the United States, and South Africa). In this model region, phytase, and the region × phytase interaction were fixed effects. However, no interactions between region and phytase were observed and therefore, the final statistical model included only region and phytase as fixed effects. Concentrations of Ca in the 20 sources of calcium carbonate ranged from 32.1 to 40.9% (Table 1). Differences in the STTD of Ca were observed among pigs fed diets containing different sources of calcium carbonate (P < 0.001). Pigs fed diets containing 1,000 units of phytase had greater (P < 0.001) STTD of Ca compared with pigs fed diets containing no phytase. The STTD of Ca in calcium carbonate from the United States was less (P < 0.001) than in calcium carbonate from Europe, Asia, or South Africa. In conclusion, the use of microbial phytase increases the STTD of Ca in calcium carbonate, but the STTD of Ca varies among different sources and among sources from different regions. Therefore, consideration should be given to differences in analyzed concentrations of Ca, values for STTD of Ca, and response to microbial phytase among different sources of Ca carbonate to ensure Ca is not being oversupplied when formulating diets.

158 Nutrient digestibility in growing pigs fed a corn distiller’s dried grains with soluble-based diet with multi-enzyme supplementation

Abstract Dietary enzyme supplementation may enhance the digestibility and utilization of non-starch components in fiber-rich feedtuffs which are increasingly used in swine diets. A xylanase/cellulase enzyme product (ENZ) was previously shown to increase the digestibility of nutrients and energy in growing pigs fed a corn-SBM diet with 30% corn dried distiller’s grains with solubles (cDDGS). To better elucidate the effects of ENZ on these components, further analysis was conducted on the fiber, non-starch polysaccharide, and ash components. A total of 12 ileal-cannulated pigs [initial body weight (BW) = 31.7 kg ± 3.04] were housed in individual metabolic crates for 21 d (period 1) and subsequently transferred to individual floor pens for an additional 28 d (period 2). These animals were assigned to 2 diets (n = 6) in a completely randomized design (CRD). The diets contained the main ingredients corn, soybean meal and cDDGS (30%) without (CON) or with ENZ supplementation. The inclusion rate of the ENZ (proprietary xylanase/cellulase product, Kerry Inc.) was 200 g/ton. Feed was formulated to 1.15% SID lysine and met or exceeded nutrient requirements for growing pigs (NRC, 2012). The diets were fed to pigs at three times maintenance energy requirement based on BW, which was assessed at 2 wk intervals throughout the study. The diets contained 0.3% titanium dioxide as an indigestible marker. In period 1, pigs had 14 d of adaptation, followed by 4 d of fecal and urine collection using the total collection method and 2 d of ileal digesta collection. In period 2, pigs had 23 days of adaptation, followed by 2 d of fecal collection and 2 d of ileal digesta collection. Data were analyzed as a CRD, using pig as the experimental unit and enzyme supplementation as the main effect. The ATTD of total NSP and galactose tended to improve in both periods 1 and 2. As consistent responses were observed in periods 1 and 2 and the ENZ X period interaction was not significant, the data from these time periods were combined for analysis. ENZ supplementation improved (P < 0.05) the ATTD of total NSP and galactose. Also, ENZ tended to improve (P < 0.10) the ATTD of cellulose and glucose from NSP. ENZ addition also increased the ATTD of calcium (P < 0.05) and tended to increase the ATTD of phosphorus (P < 0.10). In conclusion, supplementation of a corn-SBM-30% cDDGS diet with a multi-carbohydrase containing cellulase increased the ATTD of fiber, NSP and calcium in growing pigs. Novel enzymes represent a useful strategy to better utilize the nutrients in lower energy feedstuffs in monogastric animals.

36 Effects of grinding method on ileal digestibility of amino acids in different short-season corn cultivars fed to growing pigs

Abstract Decreased corn production was previously observed in Manitoba due to the low climatic temperatures; however, corn production has increased by developing corn hybrids that require low corn heat units, and therefore can grow in areas with decreased heat units. Milling technology affects feed particle size and shape, which may affect the digestibility of nutrients and growth performance of pigs. Therefore, this study aimed to determine the effects of grinding methods on the apparent (AID) and standardized (SID) ileal digestibility of amino acids (AA) in selected short-season corn cultivars fed to growing pigs. A total of 18 ileal cannulated barrows (56.8 ± 2.9 kg) were assigned to 1 of 6 dietary treatments in a triplicate 6 × 2 incomplete Latin square design with 6 diets and 2 periods to give 6 observations per treatment. Dietary treatments were arranged in a 3 × 2 factorial design with three different corn cultivars [two Manitoba-origin short-season corns (A or B) or a US-origin corn] and two grinding methods [hammer mill or roller mill]. Each ingredient was included as the sole source of protein in the diets. All diets contained 0.3% titanium dioxide as an indigestible marker. Each experimental period lasted 7 d including the first 5 d for adaptation and the last 2 d for ileal digesta collection. After feeding the experimental diets, all pigs were fed a low-protein diet for 7 d to quantify endogenous losses of N and AA for determining the SID of N and AA. Pigs were fed the diets at 2.8 times the maintenance energy requirement based on their body weight at the beginning of each period. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and replication, animal within replication, and period within replication as random effects. The AID of Arg, Ala, Ser, and Gly were greater (P < 0.05) in short-season corn B compared with US-origin corn. The AID and SID of His in both short-season corns were greater (P < 0.05) than in US-origin corn. The AID of His and SID of Thr in hammer-milled corns were greater (P < 0.05) than in roller-milled corns. A significant interaction was found whereby AID of Ile in hammer-milled corn was not different between short-season corn B cultivar and US-origin corn but in roller-milled corn, short-season corn B cultivar had a greater (P < 0.05) digestibility than US corn. In conclusion, the digestibility of AA was greater in short-season corn than in US corn, and pigs had greater digestibility of AA in hammer-milled corn than roller-milled corn.

286 Impact of feeding strategies on bodyweight and body condition in mature AI boars

Abstract The objective of this experiment was to determine how varying feeding strategies for boars impacts body weight (BW), backfat depth, loin muscle depth, Knauer caliper measurements, flank to flank tape measurement, body condition score (BCS), and scrotal width and length. This experiment was conducted over two 9-wk periods. Boars were weighed and measurements were taken every 3 wk during the study. Boars (n = 28; Acuity and Topig Norvsin) from two age groups (9 and 15 mo) and two genetic lines (maternal and terminal) were used during this experiment. Boars were blocked by breed and age and randomly allocated to receive one of the three feed intake (FI) levels of a corn-soybean meal-based diet (met NRC 2012 nutrient requirements) using the NRC (2012) maintenance equation [ME for maintenance = (100*kg BW0.75) + 15 kcal for sperm production]. Treatments were: HIGH (150% of maintenance, n = 9), MAIN (100% of maintenance, n = 10), LOW (80% of maintenance, n = 9) for the first 9-wk period. During the second 9-wk period remaining HIGH and LOW boars were crossed-over to opposite treatments (HIGH-LOW, n = 9; LOW-HIGH, n = 7) and maintenance remained unchanged (MAIN-MAIN, n = 8). Data were analyzed using PROC MIXED in SAS 9.4. Boar was the experimental unit with main effects of feed intake and age, and week serving as a repeated measure. Significance was determined at P < 0.05 and a trend at 0.05 < P ≤ 0.10. Three-way interactions of FI*Age*Week were observed during the first 9-wk period. Young boars fed HIGH had a greater increase in BW (P = 0.002), caliper (P = 0.011), backfat depth (P = 0.003), BCS (P = 0.003), and scrotal width (P = 0.004) than old boars fed HIGH and young boars fed LOW had a greater reduction in these variables then old LOW boars. Boars fed LOW for the first 9-wk period had reduced scrotal length (P = 0.004), greater reduction in BW change (P < 0.001), and reduced tape change (P = 0.021) compared with HIGH and MAIN fed boars. Two-way interactions for the second 9-wk period were observed. HIGH-LOW fed boars had decreased BW (FI*Week; P < 0.001), tape (FI*Week; P = 0.019), caliper (FI*Week; P = 0.012), BCS (FI*Week; P < 0.001), and scrotal width (FI*Week; P = 0.047) while LOW-HIGH boars had increased measurements for these variables over time. Additional two-way interactions during the second 9-wk period included Tape (FI*Age; P = 0.046) and BCS (FI*Age; P = 0.028). Overall young boars had more adverse reactions to the varying feeding strategies than old boars, this included larger changes in BW and composition measures. Young and old boars fed MAIN level lost BW and condition indicating the equation for maintenance energy requirement is not accurate for modern genetics working boars. Future research is needed with varying ages and feed intakes in the boar stud to better understand the impacts of growth, development, and maintenance energy for the modern AI boar.

Retrospective investigation of the energy requirements for weight loss and weight maintenance after weight loss programme in obese dogs.

Obesity is a highly prevalent disease in dogs and is characterized by the excessive accumulation of adipose tissue that results in metabolic changes. Its treatment is based on a negative energy balance focusing on energy restriction. However, there are few studies in dogs that assessed the energy intake needed for adequate weight loss and to weight maintenance afterward. The aim of this study was to evaluate data about the treatment of canine obesity, with emphasis on energy restriction to induce weight loss and to maintain body weight (BW) and ideal body condition after weight loss. This was a retrospective study in which records of obese dogs from a veterinary teaching hospital were assessed between 2014 and 2020. Sixteen dogs were considered in the study according to inclusion and exclusion criteria and 10 of these participated in the maintenance phase after weight loss. The animals lost a mean of 23.2% their initial weight in a mean of 422 days. The mean weekly weight loss rate was 0.58% of BW, and the mean daily energy intake for weight loss was 59 kcal/kg current BW0.75. When the target BW was considered, which was defined as the current weight minus 10% for every point in the body condition score scale above 5, the mean energy for weight loss was 71 kcal/kg target BW0.75. In the maintenance phase, the animals were assessed for a mean of 134 days. The mean energy intake to maintenance BW was 70 kcal/kg BW0.75. The lower energy requirement of obese dogs during and after weight loss can work as an alert for the formulations of therapeutic weight loss diets to contain a high nutrient density focusing on the wellbeing, health, and quality of life of obese dogs, not just for the weight loss phase, but a diet for the weight maintenance phase.

Birth weight, growth indices, and seminal parameters in male offspring are resilient features to maternal pre-conceptional dietary manipulation in sheep

Gestational diet manipulation can lead to inadequate fetal nutrient supply resulting in low birth weight, limited postnatal growth, and consequently, reduced reproductive performance in the progeny. However, effects of short-term maternal pre-conceptional dietary manipulation on postnatal growth and reproductive parameters of male offspring in large animals remains unexplored. To determine these consequences, female crossbred (Polypay x Dorset) sheep were allocated to three groups (n = 33/group) of dietary manipulation for 21 days prior to mating under the following conditions: (1) control at 100 % of maintenance energy requirements (40 Kcal of metabolizable energy/kg body weight [BW]), (2) undernutrition (UN) at 50 % of Control intake, and (3) overnutrition (ON) at 200 % of maintenance energy. Singleton ram lambs (UN:9; C:12; ON:6) were monitored from birth until 8 months of age, including birth weight, weekly weights, weight gain, body mass index (BMI), and circulating testosterone. After weaning, monthly scrotal circumference and subcutaneous fat depth were measured. Semen morphology and motility were evaluated at 7 and 8 months of age. Birth weight, weight gain, and BMI at birth and weaning were not significantly different among nutritional treatments. None of the pre-conceptional diets affected body weight change from weaning until 36 weeks of age, BMI, fat depth, or scrotal circumference across the experiment. A sustained rise in plasma testosterone concentrations was detected when ram lambs were, on average, 82 days old and 37 kg. Both testosterone concentrations and scrotal circumference were positively correlated to body weight regardless of treatment group. In addition, seminal parameters did not differ among treatments, but a transient increase in plasma testosterone at 18 weeks of age was observed in ON ram lambs compared to control rams. In conclusion, birth weight, growth indices, and seminal parameters in singleton rams are resilient features in the progeny upon maternal pre-conceptional dietary manipulation in sheep.

Energy requirement for primiparous Holstein × Gyr crossbred dairy cows

Our objective was to estimate the requirements of metabolizable energy (ME) and net energy for the maintenance (NEm) of lactating and dry cows, the efficiency of ME utilization for milk production (kl) and tissue gain (kg), and the use of body energy mobilization for milk production (kt) throughout the lactation of primiparous crossbred Holstein × Gyr cows, using open-circuit respiration chambers. Twenty-nine primiparous Holstein × Gyr crossbred cows with an initial BW averaging 563 ± 40.1 kg and 2.5 ± 0.09 years old were used throughout lactation and dry periods. The cows were kept non-pregnant throughout the study to eliminate possible confounding factors. Apparent digestibility assays, followed by calorimeter measurements, were performed 6 times throughout the lactation period. In the dry-off period, the cows were also evaluated but fed with restricted intake (DMI = 1.1% BW/d) to achieve heat production close to maintenance. After 21 d of diet adaptation, an apparent digestibility assay followed by calorimeter measurements was performed. Parameter estimates for lactation period were obtained by mixed models including lactation stage as repeated measures. For restricted feeding at dry-off and fasting period assays, the requirements were estimated by exponential regression. For whole lactation, the values of MEm and NEm were 0.588 and 0.395 MJ/BW0.75, respectively. The efficiencies klkgkt were 0.672, 0.771, and 0.814, respectively. However, MEm and NEm were higher in early and mid-lactation than late, while kl was higher in early than other lactation stages. Dry and non-pregnant cows had MEm of 0.434 MJ/BW0.75 and NEm of 0.351 MJ/BW0.75 for maintenance level, and MEm of 0.396 MJ/BW0.75 and NEm of 0.345 MJ/BW0.75 for fasting metabolism level and efficiency of ME utilization for maintenance was 0.80. Our findings confirmed that F1 crossbred Holstein × Gyr dairy cows have differences in energy requirement and efficiency throughout the lactation stages, suggesting the use of different values in each stage. The estimated values of energy requirement for maintenance and efficiencies for primiparous lactating crossbred Holstein × Gyr were similar to those reported in the literature in specific studies and requirements systems.

Effect of supplementing zilpaterol hydrochloride during different periods on energetics, growth performance, carcass traits and fatty acid profile in meat of finishing lambs

To determine the effect of adding β2 agonist zilpaterol hydrochloride during different periods on growth performance, dietary energetic, carcass traits and fatty acid profile, forty male lambs Pelibuey × Katahdin (37.70 ± 0.83 kg) were blocked by body weight and randomly assigned to pens. Treatments consisted in: 1) control, no zilpaterol supplementation, 2) zilpaterol supplementation for 20 d (ZIL20), 3) zilpaterol supplementation for 30 d (ZIL30), and 4) zilpaterol supplementation for 40 d (ZIL40). Compared with control treatment, zilpaterol supplementation increased final live weight (FLW) (3.5 %; P = 0.0563), average daily gain (ADG, 14.8 %; P = 0.0598) and gain:feed ratio (10.3 %; P = 0.0324). As well as hot carcass weight (6.1 %; P = 0.0064), dress out percentage (2.6 %; P = 0.0139) and Longissimus dorsi muscle area (13.7 %; P = 0.0015). Compared to control group, zilpaterol increased (P = 0.0413) observed vs. expected dietary of NEm (net energy requirements for maintenance) and NEg (net energy requirements for growth) (5.7 and 8.1 %, respectively). Twenty days of zilpaterol treatment improved FLW (4.4 %, P = 0.0566) and tended to improve ADG (17.4 %, P = 0.0718) when compared to control group. Only intramuscular fat showed a positive linear effect (P = 0.0006) in stearic fatty acids proportion and negative linear effect (P = 0.0585) in araquidonic fatty acid proportion. We conclude that zilpaterol hydrochloride improved variables of growth performance, energy retention and carcass traits with noticeable effects from 20 d of zilpaterol supplementation.

The effect of dietary olive polyphenols on markers of inflammation and bodyweight in senior domestic cats

Abstract The high rates of obesity and degenerative joint disease in companion animals has resulted in a demand for dietary supplements that support joint health and reduce inflammation. Polyphenols have received considerable attention in this space, although literature in companion animals is lacking or conflicting. This study determined whether a diet supplemented with olive polyphenol extract had the potential to reduce inflammation and/or bodyweight. Eight senior domestic cats aged 11.01 ± 0.74 years (mean ± standard error of the mean) and weighing 3.6 ± 0.3 kg (mean ± SEM) were used for this study. The cats were fed, ad libitum with a complete (AAFCO) canned diet supplemented with 0.1% olive polyphenol extract for 56 days. Cats were weighed weekly and blood samples taken on day 0 (baseline), 28, and 56 of the study. Biochemistry, haematology, and cytokine (19 cytokines or chemokines) panels were run for each blood sample. While there was an initial aversion to the supplemented diet, intakes of the cats increased, and they consumed enough to meet or exceed their daily maintenance energy requirements by day 10 of the trial. On average, the cats lost approximately 8% of their starting weight over the trial, which was interesting given that feed intake exceeding maintenance energy requirements for most of the study. Whether the decrease in bodyweight was due to seasonal changes, the supplemented diet, or a combination of the two warrants further investigation. There were little to no changes to any of the blood parameters, which was surprising given that previous studies have reported reductions in pro-inflammatory cytokines following polyphenol supplementation. Perhaps a higher concentration of olive polyphenols is required to elicit the anti-inflammatory response observed in other species. A study evaluating the dose-dependent effects of dietary polyphenols on inflammatory and oxidative markers in cats would be valuable in this context.

Dietary xylo-oligosaccharides and arabinoxylans improved growth efficiency by reducing gut epithelial cell turnover in broiler chickens

BackgroundOne of the main roles of the intestinal mucosa is to protect against environmental hazards. Supplementation of xylo-oligosaccharides (XOS) is known to selectively stimulate the growth of beneficial intestinal bacteria and improve gut health and function in chickens. XOS may have an impact on the integrity of the intestinal epithelia where cell turnover is critical to maintain the compatibility between the digestive and barrier functions. The aim of the study was to evaluate the effect of XOS and an arabinoxylan-rich fraction (AXRF) supplementation on gut function and epithelial integrity in broiler chickens.MethodsA total of 128 broiler chickens (Ross 308) were assigned into one of two different dietary treatments for a period of 42 d: 1) control diet consisting of a corn/soybean meal-based diet; or 2) a control diet supplemented with 0.5% XOS and 1% AXRF. Each treatment was randomly distributed across 8 pens (n = 8) with 8 chickens each. Feed intake and body weight were recorded weekly. On d 42, one male chicken per pen was selected based on average weight and euthanized, jejunum samples were collected for proteomics analysis.ResultsDietary XOS/AXRF supplementation improved feed efficiency (P < 0.05) from d 1 to 42 compared to the control group. Proteomic analysis was used to understand the mechanism of improved efficiency uncovering 346 differentially abundant proteins (DAP) (Padj < 0.00001) in supplemented chickens compared to the non-supplemented group. In the jejunum, the DAP translated into decreased ATP production indicating lower energy expenditure by the tissue (e.g., inhibition of glycolysis and tricarboxylic acid cycle pathways). In addition, DAP were associated with decreased epithelial cell differentiation, and migration by reducing the actin polymerization pathway. Putting the two main pathways together, XOS/AXRF supplementation may decrease around 19% the energy required for the maintenance of the gastrointestinal tract.ConclusionsDietary XOS/AXRF supplementation improved growth efficiency by reducing epithelial cell migration and differentiation (hence, turnover), actin polymerization, and consequently energy requirement for maintenance of the jejunum of broiler chickens.

Impact of enzyme inclusion on the digestibility of protein, amino acids, calcium and phosphorus in growing pigs depending on meal size, frequency and sampling period

When digestibility trials are conducted, pigs are typically fed twice a day with a restricted amount of feed. These conditions are not representative of the feeding conditions in commercial farm. The present study aimed to determine the effects of meal size and frequency, xylanase and phytase inclusion as well as digesta sampling period, on the digestibility of protein, amino acids (AA), calcium (Ca) and phosphorus (P). Pigs (n = 6) were fitted with a T cannula, and each received all treatments following a 2 × 3 factorial arrangement in a 6 × 6 Latin square experimental design. The diets were supplemented or not with a combination of xylanase and phytase and divided into 3 feeding programs: one received 2 meals per day that met 3 times the maintenance energy requirement (2M), one received the same quantity of feed in 8 meals (8M), and another received an amount that supplied 5 times the maintenance energy requirements in 8 meals (8M+). Digesta was sampled from 0800 to 1200, 1200–1600, 1600–2000 and 0800–2000. The results indicated an improvement in the coefficient of apparent ileal digestibility of dry matter, crude protein, P, Ca, Val and Thr with enzyme inclusion in all meal distribution (enzyme effect, P < 0.05). Apparent ileal digestibility of Ca in the 0800–1200 period was reduced in 8M+ treatment compared to 2M and 8M whereas no difference was observed for meal size or frequency in 1200–1600 and 1600–2000 periods (Interaction meal × period, P = 0.017). A meal effect was observed for coefficient of apparent total tract digestibility of Ca (meal effect, P = 0.003) which was higher by 8% in pigs fed 8M compared to 8M+ (contrast 8M vs 8M+, P = 0.040). Saturation of the absorption processes may explain lower digestibility with 8M+ . Enzyme efficacy was not affected by meal size or frequency indicating minor modifications of digestive conditions. An 8-h sampling period would allow collection of a representative sample and avoid underestimating or overestimating digestibility of certain nutrients.

High- or low-fibre diet, meal size and frequency: Effect on ileal and total tract digestibility and mean retention time in growing pigs

This study aimed to determine the effect of the size and frequency of meals and diet type (high- or low-fibre) on fibre degradation and retention time of digesta in growing pigs. Pigs (n = 6) were fitted with a T-cannula, and each received all treatments following a 2 × 3 factorial arrangement in a 6 × 6 Latin square experimental design. The diets were either corn-soybean meal-based diet with low fibre (LowFibre) or wheat-barley based diet with high fibre (HighFibre) and distributed differently: 2 meals per day that met 3 times the maintenance energy requirement (2M), the same amount of feed in 8 meals (8M), and 8 meals per day that met 5 times the requirements (8M+). A diet type × meal interaction was observed for mean retention time (MRT) of the solid and liquid phase of digesta where MRT in LowFibre diet was higher in 2M compared to 8M and 8M+ while in HighFibre only 8M had lower MRT than 2M and 8M+ (Solid phase, P = 0.023, Liquid phase, P = 0.097). Ileum digesta from the LowFibre diet was less viscous than ileum digesta from HighFibre diet (P = 0.028) regardless of the meal distribution. Concentrations of the indigestible markers in the ileal digesta (TiO2 and YbCl3) increased faster in the LowFibre compared to the HighFiber diet, and marker concentrations were more constant in the 2M than the 8M and 8M+ treatments (P < 0.05). Coefficient of apparent ileal digestibility (CAID) of dry matter, energy, crude protein, total non-starch polysaccharides (NSP) and insoluble NSP was higher in the HighFibre diet than the LowFibre diet, while opposed results were observed for apparent total tract digestibility (P < 0.05). No effect of meal type was observed on CAID. Blood glucose levels were stable throughout the day for 8M and 8M+ while blood glucose for 2M was decreased between two meals (meal × time effect, P = 0.035). Larger meals in 2M-LowFibre, 2M-HighFibre and 8M+HighFibre can therefore explain longer MRT potentially due to decreased motility and slower gastric emptying. In conclusion, feeding pigs with an increased number of meals per day allows a continuous flow of digesta, stabilized blood glucose and increased digestibility. Ingestion of a high-fibre diet causes increased digesta viscosity. The type of diet had more impact on digestibility and transit time than the meal size and frequency.

31 Importance of Good Sow Development: Focusing on Nutrition and Feeding from Gilt Development to Subsequent Parities

Abstract Continuous genetic progress leads to significant improvements in growth and efficiency of PIC Camborough gilts. As an example, gilt weight gain per day of age has increased dramatically in the past decade. This implies that gilts are heavier at a similar breeding age, which increases the likelihood of breeding overweight gilts. Additionally, sows have less backfat depth and are leaner compared with their predecessors. It has been reported that gilt retention rate until parity 3 declines when breeding gilts with over 160 kg of body weight. Hence, controlling growth rate of developing gilts could be helpful to achieve the target breeding weight (135 to 160kg). A recent study reported that reducing dietary nutrient density (ME and SID Lys) from 57 kg until breeding significantly reduced breeding weight by 4 kg (P &amp;lt; 0.05). The slower growing gilts had reduced stillborn (P &amp;lt; 0.01), had 0.79 more pigs born alive (P = 0.10), and weaned a total of 238 more pigs over three reproductive cycles. However, with the genetic trend for faster growth rate, it is inevitable to breed overweight gilts in production. Energy requirement for maintenance (MEm) of gestating sows is a function of body weight of the sow. Thus, heavier gilts at breeding need more energy for maintenance. An assessment using data from 2,475 gilts collected in commercial sow farms evaluated how different feeding levels satisfy the MEm of a gilt herd bred at 154 kg. The results showed that feeding 5.90 Mcal of ME/day or 4.40 Mcal of NE/day results in only a few gilts fed below maintenance from 90 to 112 days of gestation. However, if a decreased feeding level (5.17 Mcal of ME/day or 3.85 Mcal of NE/day) was adopted, which has been seen in production with a purpose of reducing body condition, almost all the gilts would be fed under maintenance from 90 to 112 days of gestation. Gilts are still growing and developing during their first gestation and inadequate feeding level may jeopardize their growth and development, which could lead to poor lifetime productivity. Heavier gilts become heavier sows in the subsequent parities; thus, the sows also require more energy for maintenance during subsequent gestations. Therefore, PIC recommends feeding gilts, ideal and fat sows with 5.90 Mcal of ME/day or 4.40 Mcal of NE/day throughout gestation. Feeding this level throughout gestation will result in an estimation of no overall caliper change. Whereas for thin sows that need to recovery condition, PIC recommends feeding 8.60 Mcal of ME/day or 6.50 Mcal of NE/day (Figure 1). Feeding this level throughout gestation will result in an estimated overall gain of 3 caliper units. In summary, the increased potential for growth and efficiency of PIC gilts warrants the adoption of multiple strategies to improve longevity and lifetime productivity.

PSIV-14 Effects of Maternal Nutrient Restriction During Late Gestation on Expelled Cotyledonary Mrna Expression in Primiparous Beef Females

Abstract To determine the effects of late gestational nutrient restriction on expelled cotyledonary mRNA expression, fall-calving Hereford × Simmental-Angus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 11) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth. Beginning on d 160 of gestation, heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME/kg, 6.69% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Calving was observed for all females and placentas were collected at natural expulsion. Immediately after collection (average: 4.5 h post-calving; range: 2.3 to 12.1 h post-calving), 2 representative cotyledons on the ipsilateral side were cleaned with phosphate buffered saline, and cotyledonary tissue was flash frozen. Total RNA was extracted, and RT-qPCR was performed for mRNA expression of glucose transporters (SLC2A1, SLC2A3, SLC2A4), a fructose transporter (SLC2A5), amino acid transporters (SLC1A1, SLC3A2, SLC7A1, SLC7A5, SLC7A8, SLC38A2), angiogenic factors/receptors (VEGFA, NOS3, FLT1, KDR, GUCY1B3), and pregnancy-associated glycoprotein 2 (PAG2). Relative mRNA expression was analyzed with nutritional plane, treatment initiation date, time to cotyledon sampling, and calf sex (when P &amp;lt; 0.25) as fixed effects. We have previously reported that total uterine blood flow during late gestation was not affected (P ≥ 0.20) by nutritional plane or the nutritional plane × day of gestation interaction. Post-calving, NR dams were 64 kg BW less (P &amp;lt; 0.001) and 2.0 BCS less (P &amp;lt; 0.001), but calf birth weight was not affected (P = 0.72) by nutritional plane. Contralateral placental dry weight tended to be less (P = 0.07) in NR dams, but total placental weight was not affected (P = 0.86) by late gestational nutritional plane. Cotyledonary relative mRNA expression of SLC2A3 and SLC38A2 was greater (P ≤ 0.05) and relative expression of SLC2A1, SLC2A4, and NOS3 tended to be greater (P ≤ 0.07) in NR dams compared with CON. Late gestational nutritional plane did not affect (P ≥ 0.13) cotyledonary relative mRNA expression of FLT1, GUCY1B3, KDR, PAG2, SLC1A1, SLC2A5, SLC3A2, SLC7A1, SLC7A5, SLC7A8, and VEGFA. In summary, first parity beef females who experienced late gestational nutrient restriction maintained uterine blood flow and placental mass and had 4 nutrient transporters and 1 angiogenic factor upregulated in cotyledons, all which likely contributed to their conservation of fetal growth.

PSVIII-10 An Experimental Weight Management Food Supports Metabolism and Allows for Less Calorie Restriction for Weight Loss in Both Dogs and Cats: a Retrospective Analysis

Abstract Obesity is a growing health concern in dogs and cats. Furthermore, decreased maintenance energy requirements after body weight loss has been linked to rebound weight gain in dogs and cats. Previous research completed by our group has demonstrated that feeding a targeted weight management food to dogs and cats during both the maintenance and weight loss phases results in body weight loss and improved body condition despite increases in caloric intake during the weight maintenance phase. As such, the objective of this study was to investigate the effects of feeding two different weight management foods on weight loss on a per Kcal basis in dogs and cats. Obese adult dogs (n = 39) and cats (n = 38) were subjected to a 36-d maintenance phase and then a 112-d weight loss phase in which they were fed either a standard weight management food (control) or a weight management food that included a blend of specific fibers, immuno-modulators, antioxidant and anti-inflammatory botanicals, and lipotropes (test). During the maintenance phase, pets were fed an adjusted amount of calories needed to maintain weight. Diets were adjusted throughout the weight loss phase to achieve a 1 to 2% reduction in BW per week. Intake was collected daily, and body weight (BW) was recorded every 7 d. To calculate the calorie deficit needed to achieve one unit of weight loss, metabolizable energy estimated from modified Atwater equations and food intake were used and the delta of energy intake between maintenance and body weight loss phases was divided by the delta of the BW change during weight loss. Delta energy/delta weight was reduced (P = 0.020) in cats fed the test food when compared with pets fed the control food such that cats fed the weight loss food required a deficit of 56.5 kcal/d and cats fed the control food required a deficit of 82.8 kcal/d to achieve 1 kg of BW loss. Similarly, delta energy/delta weight was reduced (P = 0.045) in dogs fed the test food when compared with dogs fed the control food such that dogs fed the weight loss food required a deficit of 57.2 kcal/d and dogs fed the control food required a deficit of 95.0 kcal/d to achieve 1 kg of BW loss. Overall, feeding the targeted weight management test food resulted in body weight loss with less of a calorie deficit when compared with feeding the control food, suggesting that the metabolism of dogs and cats is altered by the test food. These data suggest that feeding a food that requires less calorie deficit to lose body weight allows pets to consume more food, contributing to improved satiety, without negating their weight loss process. Future research may support a benefit against rebound weight gain.