Times Maintenance Energy Requirements Research Articles

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.

306 Nutrient Digestibility and Dietary Energy Values in Growing Pigs Fed a Corn Distillers Dried Grains with Soluble (Cddgs)-Based Diet with Multi-Enzyme Supplementation

Abstract Dietary enzyme supplementation may enhance the digestibility and utilization of non-starch components of the diet by pigs. This study was conducted to evaluate the efficacy of a multi-carbohydrase enzyme (ENZ) in growing pigs for apparent ileal digestibility (AID) of amino acids (AA), apparent total tract digestibility (ATTD) of nutrients and energy values in a corn distillers dried grains with solubles (cDDGS)-based diet. A total of 12 ileal-cannulated pigs [initial body weight (BW) = 31.7 kg ± 3.04] were housed in individual metabolic crates for 21 days (Period 1) and subsequently transferred to individual floor pens for additional 28 days (Period 2). These animals were assigned to 2 diets (n = 6) in a completely randomized design (CRD). The diets were formulated on corn, soybean meal and cDDGS (30%) without (CON) or with ENZ supplementation. The ENZ (Proprietary xylanase/cellulase product, Kerry Inc.) was included in the diets at 200 g/tonne. Feeds were formulated to 1.15% SID lysine and met or exceeded nutrient requirements for growing pigs (NRC, 2012). Pigs were fed diets at three times maintenance energy requirement based on BW, which was assessed at every 2 weeks intervals throughout the study, Titanium dioxide was added to the diets as an indigestible marker. In period 1, pigs had 14 d of adaptation, followed by 4 d fecal and urine using the total collection method and 2 d ileal digesta collection. In period 2, pigs had 23 days adaptation, followed by 2 d fecal collection and 2 d illeal digesta collection. The AID of AA and gross energy (GE) and ATTD of nutrients and GE were calculated by an index method. Data were analyzed as a CRD, using pig as the experimental unit and enzyme supplementation as the main effect. Overall, average daily gain and gain:feed ratio of pigs were 857 and 918 g/d and 0.52 and 0.54 for CON and ENZ, respectively (P > 0.05). In period 1, ENZ supplementation improved (P < 0.05) the ATTD of dry matter (DM), ash, organic matter (OM), neutral detergent fiber (NDF), and GE by 4.4%, 26.8%, 2.8%, 11.3%, and 3.6%, respectively. Also, ENZ tended to improve (P < 0.10) the ATTD of crude protein (CP) by 7.4% and AID of threonine, CP, and GE by 6.6%, 7.6%, and 13.7%, respectively. In period 2, ENZ improved (P < 0.05) the ATTD of DM, ash, OM, CP, NDF, and GE by 5%, 30.1%, 3.4%, 4.1%, 19.6%, and 4.2%, respectively. similarly, EMZ improved (P < 0.05) the AID of threonine, CP, and GE by 4.2%, 6.0%, and 6.4%, respectively. In conclusion, multi-carbohydrase supplementation in a corn-SBM diet with 30% cDDGS increased the digestibility of nutrients and energy in growing pigs and may represent a useful strategy to optimize the utilization of such raw material.

Impact of ergot alkaloid and steroidal implant on whole-body protein turnover and expression of mTOR pathway proteins in muscle of cattle.

Holstein steers (n = 32) were used to determine if the ergot analog, bromocriptine decreases muscle protein synthesis through inhibitory action on the mTOR pathway via a direct effect on signal proteins, and if these negative effects can be alleviated with anabolic agents. Steers were treated with intramuscular administration of bromocriptine (vehicle or 0.1 mg/kg BW) and a subdermal commercial steroidal implant containing trenbolone acetate (TBA) and estradiol 17β (with or without), in a 2×2 factorial design. During the 35 day experiment, intake was restricted to 1.5 times maintenance energy requirement. On days 27 through 32, steers were moved to metabolism stalls for urine collection, and whole-body protein turnover was determined using a single pulse dose of [15N] glycine into the jugular vein on day 28. On day 35, skeletal muscle samples were collected before (basal state) and 60 min after (stimulated state) an i.v. glucose challenge (0.25 g glucose/kg). Blood samples were collected at regular intervals before and after glucose infusion for determination of circulating concentrations of glucose and insulin. Bromocriptine reduced insulin and glucose clearance following the glucose challenge, indicating decreased insulin sensitivity and possible disruption of glucose uptake and metabolism in the skeletal muscle. Conversely, analysis of whole-body protein turnover demonstrated that bromocriptine does not appear to affect protein synthesis or urea excretion. Western immunoblot analysis of skeletal muscle showed that it did not affect abundance of S6K1 or 4E-BP1, so bromocriptine does not appear to inhibit activation of the mTOR pathway or protein synthesis. Estradiol/TBA implant decreased urea excretion and protein turnover but had no effect on protein synthesis, suggesting that steroidal implants promote protein accretion through unchanged rates of synthesis and decreased degradation, even in the presence of bromocriptine, resulting in improved daily gains. Implanted steers likely experienced increased IGF-1 signaling, but downstream activation of mTOR, S6K and 4E-BP1, and thus increased protein synthesis did not occur as expected. Overall, this data suggests that bromocriptine does not have a negative impact on muscle protein synthetic pathways independent of DMI.

Feed digestibility, digesta passage and faecal microbial biomass in desert-adapted goats exposed to mild water restriction.

In arid and semi-arid environments, extensively managed ruminants regularly experience drinking water shortage, especially in the dry season. The present study therefore investigated the effects of mild drinking water restriction on feed intake, feed digestibility, solid digesta passage and composition of faeces including faecal microbial biomass. A feeding trial was conducted in Oman, during the dry summer months. Nine adult male Batinah goats were subjected to three watering regimes in a 3×3 Latin Square design. Treatments were (1) water offered ad libitum (100%, W100); (2) water restricted to 85% ad libitum consumption (W85); and (3) water restricted to 70% ad libitum consumption (W70). Animals were offered Rhodes grass hay and whole barley grains (1:1 ratio) at 1.3 times maintenance energy requirements. Each of the three experimental periods comprised 16days of adaptation and 8days of measurements. During the latter, feed offered and refused as well as faeces were sampled and quantified. Gastrointestinal digesta passage was determined using ytterbium-labelled Rhodes grass hay. Ergosterol and amino sugars were used as markers for faecal microbial biomass, that is the sum of fungi and bacteria. Water restriction had no effect on feed intake and digesta passage. However, feed dry matter, organic matter and fibre digestibility increased (p<0.05) in W70 compared with W85, and the excreted amount of faecal dry matter, organic matter, nitrogen and neutral detergent fibre decreased (p<0.05) in W70 compared with W85. Even though water restriction did not affect total faecal microbial biomass carbon (C) concentration, that of fungal biomass C increased (p<0.05) in W70 compared with W85. Therefore, mild water restriction seems unproblematic from a physiological and nutrient utilization perspective as it increases feed digestibility without compromising feed intake.

Replacing dietary nonessential amino acids with ammonia nitrogen does not alter amino acid profile of deposited protein in the carcass of growing pigs fed a diet deficient in nonessential amino acid nitrogen.

Amino acid usage for protein retention, and, consequently, the AA profile of retained protein, is the main factor for determining AA requirements in growing animals. The objective of the present study was to determine the effect of supplementing ammonia N on whole-body N retention and the AA profile of retained protein in growing pigs fed a diet deficient in nonessential AA (NEAA) N. In total, 48 barrows with a mean initial BW of 13.6 kg (SD 0.7) were used. At the beginning of the study, 8 pigs were euthanized for determination of initial protein mass. The remaining animals were individually housed and fed 1 of 5 dietary treatments. A common basal diet (95% of experimental diets) was formulated to meet the requirements for all essential AA (EAA) but to be deficient in NEAA N (CP = 8.01%). The basal diet was supplemented (5%) with cornstarch (negative control) or 2 N sources (ammonia or NEAA) at 2 levels each to supply 1.35 or 2.70% extra CP. The final standardized ileal digestible (SID) NEAA content in the high-NEAA-supplemented diet (positive control) was based on the NEAA profile of whole-body protein of 20-kg pigs, and it was expected to reduce the endogenous synthesis of NEAA. Pigs were fed at 3.0 times maintenance energy requirements for ME in 3 equal meals daily. At the end of a 3-wk period, pigs were euthanized and the carcass and visceral organs were weighed, frozen, and ground for determination of protein mass. From pigs in the initial, negative control, high-ammonia, and high-NEAA groups, AA contents in the carcass and pooled visceral organs were analyzed to determine the total and deposited protein AA profile, dietary EAA efficiencies, and minimal de novo synthesis of NEAA. Carcass weight and whole-body N retention linearly increased ( < 0.05) with N supplementation. The AA profile of protein and deposited protein in the carcass was not different ( > 0.10) between N sources, but Cys content increased ( < 0.05) with NEAA compared with ammonia in visceral organ protein and deposited protein. The dietary SID EAA efficiency for increasing EAA deposition in whole-body protein increased ( < 0.05) with N supplementation, but it was not different ( > 0.10) between N sources. The de novo synthesis of NEAA increased ( < 0.05) for ammonia compared with NEAA supplementation. In conclusion, adding ammonia as a N source to diets deficient in NEAA N increases whole-body N retention without affecting the carcass AA profile.

Nitrogen from ammonia is as efficient as that from free amino acids or protein for improving growth performance of pigs fed diets deficient in nonessential amino acid nitrogen.

Inclusion of NPN in diets may compensate the deficient supply of nonessential AA (NEAA) in very low CP levels. To assess this, 2 studies were conducted to determine the effect of supplementing NPN and specific NEAA to diets severely deficient in NEAA nitrogen (NEAA-N) on growth performance of pigs. In Exp. 1, 48 gilts (initial BW 15.2 ± 1.3 kg; 2 pigs per pen; 6 pens per treatment) were randomly assigned to 1 of the 4 dietary treatments: 1) positive control (Pos Ctrl), not deficient in essential AA (EAA) and total N, with all N supplied from intact protein (casein and soybean meal) or crystalline EAA, (2) negative control (Neg Ctrl), supplying the same amount of potentially limiting EAA as Pos Ctrl but deficient in NEAA-N, 3) Neg Ctrl plus 1.45% CP from ammonia-N (low NPN), and 4) Neg Ctrl plus 2.90% CP from ammonia-N (high NPN), supplying the same amount of digestible N as the Pos Ctrl diet. Pigs were fed ad libitum, and ADG and ADFI were monitored weekly during a 3-wk period. Gain:feed improved linearly ( < 0.05) with supplementation of ammonia-N in diets. Gain:feed for high NPN was similar ( = 0.496) to that for Pos Crtl (0.51 and 0.52, respectively). In the Exp. 2, 72 individually housed barrows (initial BW 13.5 ± 0.6 kg; 8 pigs per treatment) were assigned to 9 dietary treatments. A basal diet was formulated to be deficient in NEAA-N with a ratio of EAA-N to total N (EAA-N:TN) of 0.74. The basal diet was supplemented with 1 of 4 different N sources (urea, ammonia, glutamic acid, and a mixture of NEAA) at 2 levels each, decreasing the final EAA-N:TN to 0.63 and 0.55, respectively. Pigs were fed at 3.0 times maintenance energy requirements during 9 d of adaptation and 3 wk of observations. Body weight was monitored weekly. At the end of the experiment, blood samples from the portal vein and abdominal aorta were collected to determine ammonia- and urea-N concentrations. Final BW, ADG, and G:F increased ( < 0.05) with supplemented ammonia, glutamate, and the NEAA mix but not (> 0.10) with urea. Final BW, ADG, and G:F were not different ( > 0.05) between pigs fed the ammonia, glutamate, and NEAA mix supplemented diets. Urea concentration in portal and arterial blood plasma increased linearly ( < 0.05) with urea intake. In conclusion, growing pigs can utilize N from ammonia as efficiently as intact protein or NEAA as a source of extra N when diets are severely deficient in NEAA-N.

Evaluating the effects of late-gestation supplementation on timed–artificial insemination pregnancy rates and body composition in beef cattle

ABSTRACT Nonlactating Angus cross beef cows were used to evaluate pregnancy rates and postpartum performance following late-gestation liquid protein or dried distillers grains (DDG) supplementation. In Exp. 1, 166 multiparous cows were stratified by BW, BCS, age, and pregnancy status to receive a free-choice liquid-protein or DDG supplement fed to be isonitrogenous for 77 d during late gestation. In Exp. 2, 53 nulliparous and 36 primiparous cows were stratified similar to Exp. 1 and fed DDG at maintenance (DDG-1) or 1.2 times maintenance (DDG-1.2) energy requirements for 44 d during late gestation. Body weight and BCS were measured at initial supplementation, calving (except BW), timed AI, and weaning to determine BW and BCS change. Cows were sorted into 3 age groups (Exp. 1) and evaluated for BW and BCS change at weaning. All females were synchronized with a 7-d CO-Synch plus controlled intravaginal drug-release protocol with 72 h of timed AI. In Exp. 1, cows fed DDG had greater (P 0.10) on BW or BCS change. Timed-AI pregnancy rates were similar (P > 0.10) across treatments for both experiments. Late-gestation supplementation with DDG had positive effects on animal performance, with the greatest effect in the younger females.

Production attributes of Merino sheep genetically divergent for wool growth are reflected in differing rumen microbiotas

Divergent genetic selection for wool growth as a single trait has led to major changes in sheep physiology and metabolism, including variations in rumen microbial protein production and uptake of α-amino nitrogen in portal blood. This study was conducted to determine if sheep with different genetic merit for wool growth exhibit distinct rumen bacterial diversity. Eighteen Merino wethers were separated into groups of contrasting genetic merit for clean fleece weight (CFW; low: WG− and high: WG+) and fed a blend of oaten and lucerne chaff diet at two levels of intake (LOI; 1 or 1.5 times maintenance energy requirements) for two seven-week periods in a crossover design. Bacterial diversity in rumen fluid collected by esophageal intubation was characterized using 454 amplicon pyrosequencing of the V3/V4 regions of the 16S rRNA gene. Bacterial diversity estimated by Phylogenetic distance, Chao1 and observed species did not differ significantly with CFW or LOI; however, the Shannon diversity index differed (P=0.04) between WG+ (7.67) and WG− sheep (8.02). WG+ animals had a higher (P=0.03) proportion of Bacteroidetes (71.9% vs 66.5%) and a lower (P=0.04) proportion of Firmicutes (26.6% vs 31.6%) than WG− animals. Twenty-four specific operational taxonomic units (OTUs), belonging to the Firmicutes and Bacteroidetes phyla, were shared among all the samples, whereas specific OTUs varied significantly in presence/abundance (P<0.05) between wool genotypes and 50 varied (P<0.05) with LOI. It appears that genetic selection for fleece weight is associated with differences in rumen bacterial diversity that persist across different feeding levels. Moderate correlations between seven continuous traits, such as methane production or microbial protein production, and the presence and abundance of 17 OTUs were found, indicating scope for targeted modification of the microbiome to improve the energetic efficiency of rumen microbial synthesis and reduce the greenhouse gas footprint of ruminants.

Effect of ractopamine on whole body and splanchnic energy metabolism in Holstein steers

This study was designed to examine the influence of ractopamine (RAC) on whole-body and splanchnic energy balance. Six growing Holstein steers [body weight (BW) = 402 ± 39.5 kg] surgically fitted with an arterial and portal, hepatic, and mesenteric venous indwelling catheters were used in a repeated measures study. Treatments were a basal diet of alfalfa cubes fed at approximately 1.5&amp;times maintenance energy requirements (days 1-21) and basal plus RAC (430 mg head d-1; days 22-42). On day 14 of each period, splanchnic and portal-drained viscera (PDV) energy balances were determined as the product of arterio-venous O2 difference and blood flow. Blood flow was determined using down-stream dilution of p-aminohippuric acid. Whole-body energy balance was determined on days 15-21 of each period, which included 7 d total excreta collection and 3 d of respiratory gas exchange measurements. Body weight and DM intake were greater (P &lt; 0.05) for steers receiving RAC compared with those receiving the control diet; however, no difference was observed in either BW or DMI when expressed on a BW0.75 basis. Similarly, as a function of BW0.75, whole-body heat production (691 kJ kg BW0.75 d-1; P = 0.96) and retained N (0.85 g kg BW0.75 d-1; P = 0.34) and energy (298 kJ kg BW0.75 d-1; P = 0.71) were unaffected by RAC. In contrast, RAC tended to decrease (P = 0.09) energy use by splanchnic tissues (191 vs. 156 kJ kg BW0.75 d-1), largely due to a reduction (P = 0.12) in energy use by the PDV (100 vs. 86 kJ kg BW0.75 d-1). These data indicate that although whole-body energy use is not affected by RAC, energy use by splanchnic tissues is decreased, thereby increasing energy use by peripheral tissues.Key words: Bovine, ractopamine, beta-agonist, energy balance, metabolism

Nutrient net absorption across the portal-drained viscera of forage-fed beef steers: Quantitative assessment and application to a nutritional prediction model1

This study aimed to establish the relationship between ME intake and energy and nutrient absorption across the portal-drained viscera (PDV) of forage-fed beef steers. Eight Angus (328 +/- 40 kg of BW) steers were surgically fitted with portal, mesenteric arterial, and mesenteric venous catheters, and were fed alfalfa cubes in a replicated 4 x 4 Latin square design with 4 levels of energy intake between 1 and 2 times maintenance energy requirements. On d 28 of each experimental period, p-aminohippuric acid was infused to measure blood and plasma flow across the PDV, and blood samples (1 every hour, for 6 h) were collected simultaneously from arterial and venous catheters for net absorption measurements. Oxygen utilization, and therefore energy utilization, increased (P < 0.05) linearly in relation to ME intake. Glucose net uptake was unaffected, but lactate net release increased linearly in response to ME intake (P < 0.05). Net absorption of all AA except tryptophan, glutamate, and glutamine increased linearly with ME intake (P < 0.05). The constant net absorption of glutamate and glutamine indicated increased net utilization of these AA when dietary supply was increased. These data provide quantitative measures of the PDV effects on energy and AA availability for productive tissues, and suggest that the greater net utilization of some AA when ME intake is increased could relate to their catabolism for energy production. Prediction estimates of small intestinal AA absorption, based on the Cornell Net Carbohydrate and Protein System (CNCPS), exceeded observed net AA PDV absorption. Mean bias represented the greatest proportion (87 to 96%) of the deviation between individual AA absorption and observed net AA PDV absorption, suggesting that the CNCPS model may be used to predict AA net absorption when factors describing AA utilization by the PDV are applied to model predictions.

The effect of feed restriction on belly nosing behaviour in weaned piglets

Belly nosing is an abnormal behaviour pattern most commonly seen in early-weaned piglets. Because belly nosing resembles massaging the sow's udder, it has been suggested that the behaviour is redirected suckling and may be associated with hunger or feeding motivation. The objective of this study was to determine the effect of feed restriction on the behaviour of newly weaned piglets. Eight groups of four piglets were fed ad libitum during weeks 1, 2 and 3 post-weaning (control), while treatment piglets (eight groups of four) were fed ad libitum during weeks 1 and 3, and feed restricted during week 2. During restriction, ad libitum intake from the previous day was determined from control groups (voluntary intake of 1.9 times maintenance energy requirement), averaged, and treatment piglets were provided with 65% of this amount (1.2 times maintenance energy requirement). While both groups continued to gain weight during the restriction period, weight gain was significantly lower for restricted piglets compared to controls ( P < 0.05). Behaviour was observed on days 5, 7, 9, 12, 14, 17, and 20 post-weaning using a 5-min scan sampling method for 6 h/day. During the period of restriction, treatment piglets spent less time at the feeder (5.3 ± 0.9%; controls, 8.3 ± 0.6%, P < 0.05) and more time nosing and chewing at the pen (4.1 ± 1.0%; controls 1.4 ± 0.4%, P < 0.05) compared to controls. Mean percentage of time spent belly nosing was not statistically different (3.5 ± 0.89%; controls 2.1 ± 0.53%, P = 0.13), but the variation among piglets was significantly greater in treatment groups ( P < 0.05) during the restriction period. During the post-restriction period, treatment piglets engaged in significantly more belly nosing behaviour (1.8 ± 0.6%; controls, 0.5 ± 0.2%, P < 0.05), while nosing and chewing at the pen was similar between the two groups. Feed restriction stimulated foraging-type behaviour directed at the pen during the period of restriction, and increased and altered the time course for belly nosing, but it did not elicit belly nosing in all pigs. Individual differences in response to feed restriction suggest that there is a causal relationship between low feed intake and belly nosing, but only in piglets with a predisposition for the behaviour.

Methane production in cattle calculated by the nutrient composition of the diet

In this study data originating from complete metabolic trials with cattle of both sexes, fed 337 rations at feed intake levels between one to three times maintenance energy requirement were used to regress the total CH4 emission to the level of DM intake and to the nutrient composition, respectively. A major component of the measured CH4 emission cannot be explained by DM intake but is rather due to differences in dietary nutrient composition. The amount of digestible nutrients especially of the carbohydrate fraction (starch, sugar, N-free residuals) are reliable to estimate CH4 release with high precision (r 2 = 0.885). Its production rate increased to 1.9-fold higher levels (range 1.8 – 2.1) per g of N-free residuals compared to that induced per g of protein, starch or sugar, respectively. Furthermore, diets rich in fat reduced CH4 formation in the rumen. The regression equations fit a wide range of diets and diet compositions, and more importantly, they are applicable to various types of production systems.

Effects of amount of intake and stage of forage maturity on urinary allantoin excretion and estimated microbial crude protein synthesis in the rumen of steers

Using ruminally cannulated steers, we investigated how urinary allantoin excretion was related to variations in feed intake and stage of forage maturity. Further, different approaches were compared for predicting ruminal microbial crude protein (MCP) synthesis and its efficiency. Experimental diets were arranged in a replicated 3 x 3 Latin square design (experiment 1) and a 4 x 4 Latin square design (experiment 2). In experiment 1, a mixed diet [forage to concentrate, 68:32 on a dry matter (DM) basis] was fed at three intake levels corresponding to 1, 1.5 and 2 times maintenance energy requirements. In experiment 2, four silage-based diets were fed based on perennial ryegrass (Lolium perenneL.), which was harvested at four maturity stages. Both experiments demonstrated the influence of diet on microbial growth rate and by this on efficiency of MCP synthesis, although the magnitude of the effects differed between approaches used for estimating MCP. Linear functions satisfactorily characterised the relationship between urinary allantoin excretion (y) and digestible organic matter (OM) intake (x, kg/day; experiment 1: y = 7.94 + 17.34 x; R(2) = 0.785) or intake of OM effectively degraded in the rumen (x, kg/day; experiment 2; y = 22.32 + 5.93 x; R(2) = 0.695). Urinary excretion of allantoin permitted a semi-quantitative prediction of MCP synthesis: ranking of diets and magnitude of changes in MCP synthesis were reflected.

Increasing dietary pectin level reduces utilization of digestible threonine intake, but not lysine intake, for body protein deposition in growing pigs1

Two N balance studies were conducted to investigate the effects of feeding graded levels of pectin (a soluble nonstarch polysaccharide, NSP) on the utilization of ileal digestible threonine (Thr; Thr study) and lysine (Lys; Lys study) intake for body protein deposition (PD) in growing pigs. In each study, eight Yorkshire barrows with an average initial BW of 17.2 +/- 1.3 (Thr study) and 14.3 +/- 1.4 kg (Lys study) were fed each of five experimental diets during five subsequent experimental periods, according to a crossover design. Pigs were fed twice daily at 2.6 times maintenance energy requirements. The soybean- and cornstarch-based diets, in which either Thr or Lys was the first-limiting nutrient, were formulated to contain (as-fed basis) 0, 4, 8, or 12% pectin or 8% cellulose (water-insoluble NSP), respectively, and with NSP substituting cornstarch. Across treatments, the mean daily Thr and Lys intake were 5.42 +/- 0.04 g/d (Thr study) and 7.98 +/- 0.12 g/d (Lys study), respectively. Apparent and standardized ileal digestibilities of Thr and Lys were determined in a separate study. Mean PD was 93.4, 90.2, 82.1, 76.7, and 87.9 g/d (SEM = 1.3; Thr study) and 90.7, 88.6, 87.8, 85.3, and 88.1 g/d (SEM = 1.1; Lys study) for the five respective treatments. Utilization of ileal digestible Thr intake, but not of ileal digestible Lys intake, for PD decreased linearly with dietary pectin level, and was not influenced by diet cellulose level. The current study indicates that apparent and standardized ileal digestibility values do not provide an accurate predictor of dietary effects on the utilization of ileal digestible Thr intake for protein deposition in growing pigs fed diets containing soluble NSP.

Long-term response to feeding level in lactational performance of Boran (Bos indicus) and Boran ✕ Holstein cows

AbstractIn an experiment lasting from 1.5 years before first calving until third parturition, 24 purebred indigenous Bos indicus (Boran) cows and 24 Boran crosses with Holstein (proportionately 0.50 and 0.75 Holstein blood level) were given a diet composed of Bermuda grass hay and wheat bran (0.65: 0.35) offered at low, medium and high level. This level was adapted in amount to actual body weight every 2nd week corresponding to assumed 1.0, 1.2 and 1.4 times maintenance energy requirements. Cows were subjected to working exercise before and after first parturition. Body weight differences (lower with low and medium feeding level) developed mostly before calving for the first time and showed the typical decline at the start of lactation and increase in the dry period. Additionally, Boran cows given the high level increased their body weight from the first to the second lactation cycle. Body condition scores were higher in the Boran cows and, in both genotypes, with high feeding level. Independent of feeding level and genotype, calving intervals in cycles 1 and 2 were 530 and 421 days, respectively. Lactation length was considerably shorter in the Boran cows than in the crossbred cows. Milk yield, calculated over the first 13 weeks of lactation and over the whole lactation in both cycles, was 2.06 and 3.06 times higher in the crossbreds than in the Boran. Milk of Boran cows had 1.30, 1.15 and 1.20 times higher contents of fat, total solids and protein. In the first 13 weeks of lactation, milk yield of crossbreds with high feeding level (8.7 kg/day) was higher (P &lt; 0.05) than that of the crossbreds with medium (6.5 kg/day) and low feeding level (5.4 kg/day), respectively. Boran cows never showed a significant response in milk yield to feeding level. Accordingly, the amount of organic matter intake required per kg milk increased with feeding level in the Boran cows while it remained unaffected in the crossbreds. Organic matter digestibility, as measured in lactation cycle 1, was higher (P &lt; 0.01) in Boran. Response to high feeding level and estimated maintenance requirements of crossbred cows corresponded with current assumptions, but crossbreds subjected to medium feeding level expressed unexpectedly little difference from those receiving the low level. It seems that current recommendations are not generally applicable to indigenous tropical breeds as these responded differently from crossbreds to feeding level.

Effect of pre- and postmating nutritional manipulation on plasma progesterone, blastocyst development, and the oviductal environment during early pregnancy in gilts.

Two experiments were conducted to determine mechanisms mediating effects of nutritional manipulation before and after mating on embryonic survival in pigs. Experiment 1 studied the mechanisms by which continued high feeding levels after mating result in differences in plasma progesterone during early pregnancy. Gilts fed 2.0 times maintenance energy requirements either remained on this high level or feed was reduced to 1.5 times maintenance immediately after mating. Ovarian, oviductal, and jugular vein progesterone concentrations were determined 72 h after onset of estrus, and samples taken every 4 h were used to determine LH and progesterone during the periestrous period. Treatment did not affect peripheral progesterone concentrations, the timing or rate of rise of progesterone, or progesterone in ovarian, oviductal, or jugular veins at the time of surgery. Time after the LH peak was highly correlated (P = 0.0001) with jugular progesterone concentrations, but not with those in oviductal and ovarian veins, suggesting that responses in the reproductive tract mediated by peripheral progesterone concentrations will be temporally different to effects within tissues supplied by the ovarian and oviductal vasculature. Experiment 2 studied mechanisms mediating nutritional manipulation in the preovulatory period on postovulatory reproductive function, using feed restriction during the first (RH) or second (HR) week of the estrous cycle. Surgeries were performed 12 to 20 h after ovulation, and fertilized oocytes were cultured for 144 h in vitro. Ovulation rate was not affected by previous nutritional regimen. Fertilization rate was higher (P = 0.056) in RH vs HR gilts, but development of cultured oocytes was not affected by treatment. There were no treatment differences in peripheral or oviductal plasma progesterone, estradiol, or insulin-like growth factor-I (IGF-I) at surgery, or in porcine oviductal secretory protein abundance and IGF-I concentrations in oviduct flushings, but treatment affected total protein concentration (P = 0.002). These results indicate that either previous nutritional treatment does not affect the early developmental competence of fertilized oocytes in vitro or differences in developmental competence of oocytes are not expressed up to the early blastocyst stage. However, the lack of an effect of previous nutrition on steroids in the local oviductal circulation may also be related to the lack of effects on oviductal function and embryonic development.

Digestible energy and amino acid contents in Canadian varieties of sorghum, pearl millet, high-oil corn, high-oil–high-protein corn and regular corn samples for growing pigs

Fecal digestible energy (DE) and ileal digestible crude protein (CP) and amino acid (AA) contents in sorghum, pear millet, high-oil corn, high-oil-high-protein corn, regular corn I and II were determined in growing pigs fitted with ileal “T ”cannulas. The cereal grain samples were grown in Canada and supplemented with vitamins and minerals to produce six experimental diets. Six pigs, with an average initial body weight of 17 kg, were fed the diets during six subsequent experimental periods according to a Latin square design. Pigs were fed twice daily at 2.6 times maintenance energy requirements. After a 7-d adjustment period, feces were collected for 3 d, followed by a 48-h collection of ileal digesta. Apparent and standardized ileal AA digestibilities were calculated. The high-oil corn and high-oil-high-protein corn had the highest (P &lt; 0.05) DE content [4029, 4048 kcal kg-1 dry matter (DM), respectively]. The sorghum had a higher (P &lt; 0.05) DE content (3941 kcal kg-1 DM) than pear millet (3603 kcal kg-1 DM) and regular corn I (3710 kcal kg-1 DM basis) and similar DE content to regular corn II (3945 kcal kg-1 DM). Contents of standardized ileal digestible CP and AA varied between cereal grains were generally highest (P &lt; 0.05) for PM (CP: 101.6 g kg-1 DM; lysine, methionine plus cysteine, threonine: 3.4, 4.8 and 4.3 g kg-1 DM, respectively), HOPC (CP: 100.9 g kg-1 DM; lysine, methionine plus cysteine, threonine: 3.1, 5.4 and 4.3 g kg-1 DM, respectively) and similar for the other cereal grains (CP: 94.1–98.4 g kg-1 DM; lysine, methionine plus cysteine, threonine: 2.6–3.0, 3.4–4.3 and 3.3–4.0 g kg-1 DM, respectively). Differences in feeding values of these cereal grains should be considered when evaluating their potential inclusion in pig diets. Key words: Grains, pigs, energy, amino acids, digestibility

Effect of diet quantity and urea supplementation on oocyte and embryo quality in sheep

The objective was to investigate the effects of dietary energy and urea supplementation on oocyte and embryo quality in sheep using in vivo and in vitro experimental models. Sixty-three ewes were fed grass metal at 0.5 or 2.0 times maintenance energy requirements (MER). The diet was supplemented with feed grade urea (U) for half of the ewes on each energy treatment. Ewes were stimulated with 1000 IU eCG and either slaughtered on the day of pessary withdrawal for in vitro embryo production, or mated and slaughtered on Day 5 for embryo recovery. Urea decreased cleavage rate (48.3 vs 39.7%) and consequently blastocyst rate (41.6 vs 36.8%) but the differences were not significant. Oocytes from animals on 2.0 MER had a lower cleavage rate (54.9 vs 36.0%) and blastocyst yield (49.3 vs 31.4%) than those on 0.5 MER. However, there was an interaction between urea and energy for cleavage (P = 0.04) and blastocyst yield (P = 0.03) indicating a variable response to urea in the presence of high energy. This was manifested by a decrease in cleavage rate in the presence of urea and high energy (22%, 8 of 36), and a reduction in blastocyst development (19%, 7 of 36). When blastocyst development rate was expressed as a proportion of cleaved oocytes there was no difference between groups; in addition, there was no difference between groups in terms of blastocyst hatching rate (overall mean 66.1%) or blastocyst cell number on Day 8 (overall mean ± SEM, 138.4 ± 9.0, n=61). The effect of urea on cleavage rate in vivo was more severe. Urea supplementation reduced (P<0.001) the cleavage rate (93 vs 62%). Despite this, the yield of blastocysts was unaffected. Oocytes from ewes on 0.5 MER exhibited a lower (P<0.05) cleavage rate than those on 2.0 MER (66 vs 87%). This effect was also apparent at the blastocyst stage (40.0 vs 50.9%), although the difference was no longer significant. There were no differences in hatching rate (overall mean 70.7%) or blastocyst cell numbers (overall mean ± SEM, 166.3 ± 15.6 n=40). Collectively, these results suggest that both high dietary energy and urea content influence subsequent embryo development in vitro, and the deleterious effects of urea are likely influenced by concomitant energy intake.

Effect of nutrition and superovulation on oocyte morphology, follicular fluid composition and systemic hormone concentrations in ewes

The objective was to determine the effect of dietary intake on follicle and oocyte morphology in unstimulated and superovulated ewes. Fifty-four ewes were fed grass meal at 0.5, 1.0 or 2.0 times maintenance energy requirements (M) for 32 days. Oestrous cycles were synchronized using progestagen pessaries and either unstimulated or superovulated with 200 mg pig FSH. The ewes were killed and ovaries were collected either 36 or 12 h before the anticipated LH surge. Serum progesterone concentrations in ewes on day 10 after withdrawal of the pessary were lower in ewes fed 2.0M than in ewes fed 0.5M or 1.0M (P < 0.05). LH pulse frequency tended to be higher in ewes fed 2M than 1M (1.0 +/- 0.3 versus 0.3 +/- 0.2 pulses per 8 h) on day 6 after removal of the pessary but the effect was not significant. In unstimulated ewes, more follicles (>/= 3 mm) were observed when the animals were killed in ewes fed 2.0M (3.5 +/- 0.3) than in ewes fed 0.5M (2.4 +/- 0.3) or 1.0M (2.4 +/- 0.5; P < 0. 05). Fewer follicles were observed in superovulated ewes on 0.5M (7. 5 +/- 1.2) than in ewes on 1.0M (12.0 +/- 0.5) or 2.0M (12.3 +/- 1. 4; P < 0.05). Follicular fluid progesterone concentrations were higher in ewes fed 0.5M compared with those fed 1M or 2M (P < 0.05). Insulin-like growth factor (IGF)-I concentrations were higher in follicular fluid from ewes on 1M compared with either those on 0.5M or 2M (P < 0.05), whereas IGF-II concentrations were lower in follicular fluid from ewes on 2M compared with those on 1M or 0.5M (P < 0.05). Superovulation increased follicular fluid progesterone, oestradiol, IGF-I and IGF-II concentrations (P < 0.01). Concentrations of the 34, 22 and 20 kDa IGF binding proteins were lower in follicles from superovulated ewes compared with unstimulated ewes (P < 0.05). Oocytes from superovulated ewes showed abnormalities such as premature activation of cumulus expansion and vacuolation of the nucleolus and increased frequency of detachment of interchromatin-like granules from the nucleolar remnant. Collectively, these results indicate that both high and low dietary intakes can alter systemic and follicular fluid hormone concentrations. Relative to dietary effects, the effects of superovulation were greater and involved substantial increases in follicular fluid hormone concentrations and abnormal oocyte morphology.

Rumen contents and ruminal and faecal particle size distribution in steers fed a mixed diet at three amounts of intake

This study was conducted to investigate the effects of intake of a mixed diet by cattle and time post-feeding on rumen contents and on particle size distribution of ruminal digesta. Six ruminally cannulated steers received a mixed diet consisting on an average of (% of dry matter) 43 perennial ryegrass silage, 25 maize silage, 30 concentrate and 2 mineral-vitamin mix. The experimental design was a repeated 3 × 3 Latin square with 21 day periods. The diet was offered twice daily (07:00 and 19:00 h) at approximately 1, 1.5 and 2 times of estimated maintenance energy requirements (denoted low, medium and high intake, respectively). The rumens were evacuated manually at 3 and 7.5 h post-feeding and total ruminal contents separated into mat and bailable liquids. Dry matter weight distribution of total recovered particles was determined by a wet-sieving procedure and used to partition ruminal mat and bailable liquids among percentages of large (≥ 4.0 mm), medium (< 4.0 mm and ≥ 1.0 mm), and small (< 1.0 mm and ≥ 0.063 mm) particles. Intake did not influence markedly the distribution of different particle fractions, whereas time post-feeding had a pronounced effect. With increasing time after feeding, percentage of particles ≥ 1 mm decreased, whereas the percentage of particles < 1 mm increased, illustrating intensive particle breakdown in the reticulo-rumen. Dry matter contents and the proportion of particulate dry matter in the rumen increased as intake increased, i.e. ruminal mat increased at the expense of bailable liquids. From this study it can be concluded that feeding a mixed ration to steers at intakes of 1 to 2 times maintenance energy requirements influences the structure of rumen contents without changing the processes of particle breakdown.