The objective was to investigate the effect of intake before fasting on concentrations of metabolites and hormones, respiratory quotient (RQ) and fasting heat production (HP) using the washed rumen technique and to compare these values with those from the fed state. Six Holstein steers (360±22 kg) were maintained at 21°C and fed three different energy intakes within a replicated 3×3 Latin square design with 21-day periods. Steers were fed alfalfa cubes to provide 1.0, 1.5 and 2.0×NEm during 19 days of each experimental period. Steers were placed in individual metabolism stalls fitted with indirect calorimetry head-boxes on day 20 of each experimental period (FED steers) and fed their normal meal. On day 21 of each period the reticulorumen was emptied, washed and refilled with ruminal buffer (NaCl=96; NaHCO3=24; KHCO3=30; K2HPO4=2; CaCl2=1.5; MgCl2=1.5 mmol/kg of buffer) aerated with 75% N2 and 25% CO2 before introduction to the rumen (steers were not fed; WASHED steers). Each gas exchange was measured over 24 h. HP for 1.0, 1.5 and 2.0×NEm were 479, 597 and 714 kJ/daykg0.75 (s.e.m. =16), respectively. The plateau RQ was 0.756, 0.824 and 0.860 for the 1.0, 1.5 and 2.0×NEm intakes for the FED steers, respectively. After rumen washing, fasting HP was 331, 359 and 400 kJ/daykg0.75 (s.e.m.=13) for 1.0, 1.5, and 2.0×NEm intakes before fasting, respectively. The RQ for WASHED rumen steers was 0.717, 0.710 and 0.719, respectively. Cortisol and β-hydroxybutyrate concentrations in WASHED rumen steers did not exceed threshold levels for severe energy deficit and stress as can be induced from prolonged fasting. This study demonstrates that a fasting state can be emulated using the washed rumen technique, minimizing the time required as opposed to traditional fasting methodologies, without causing a severe energy deficit and stress.

The aim of this work was to investigate the variations of milk fatty acid (FA) composition because of changing paddocks in two different rotational grazing systems. A total of nine Holstein and nine Montbéliarde cows were divided into two equivalent groups according to milk yield, fat and protein contents and calving date, and were allocated to the following two grazing systems: a long duration (LD; 17 days) of paddock utilisation on a heterogeneous pasture and a medium duration (MD) of paddock utilisation (7 to 10 days) on a more intensively managed pasture. The MD cows were supplemented with 4 kg of concentrate/cow per day. Grazing selection was characterised through direct observations and simulated bites, collected at the beginning and at the end of the utilisation of two subsequent MD paddocks, and at the same dates for the LD system. Individual milks were sampled the first 3 days and the last 2 days of grazing on each MD paddock, and simultaneously also for the LD system. Changes in milk FA composition at the beginning of each paddock utilisation were highly affected by the herbage characteristics. Abrupt changes in MD milk FA composition were observed 1 day after the cows were moved to a new paddock. The MD cows grazed by layers from the bottom layers of the previous paddock to the top layers of the subsequent new paddock, resulting in bites with high organic matter digestibility (OMD) value and CP content and a low fibre content at the beginning of each paddock utilisation. These changes could induce significant day-to-day variations of the milk FA composition. The milk fat proportions of 16:0, saturated FA and branched-chain FA decreased, whereas proportions of de novo-synthesised FA, 18:0, c9-18:1 and 18:2n-6 increased at paddock change. During LD plot utilisation, the heterogeneity of the vegetation allowed the cows to select vegetative patches with higher proportion of leaves, CP content, OMD value and the lowest fibre content. These small changes in CP, NDF and ADF contents of LD herbage and in OMD values, from the beginning to the end of the experiment, could minimally modify the ruminal ecosystem, production of precursors of de novo-synthesised FA and ruminal biohydrogenation, and could induce only small day-to-day variations in the milk FA composition.

Fasting heat production (FHP) is used for characterizing the basal metabolic rate of animals and the corresponding maintenance energy requirements and in the calculation of net energy value of feeds. In broilers, the most recent FHP estimates were obtained in the 1980s in slow-growing and fatter birds than nowadays. The FHP values (n=73; six experiments) measured in 3 to 6-week-old modern lines of broilers weighing 0.6 to 2.8 kg and growing at 80 to 100 g/day were used to update these literature values. Each measurement was obtained in a group of fasting broilers (5 to 14 birds) kept in a respiration chamber for at least 24 h. The FHP estimate corresponds to the asymptotic heat production corrected for zero physical activity obtained by modeling the decrease in heat production during the fasting day. The compilation of these data indicates that FHP was linearly related to the BW0.70 (in kg), which can be considered as the metabolic BW of modern broilers. The 0.70 exponent differs from the conventional value of 0.75 used for mature animals. The FHP per kg of BW0.70 ranged between 410 and 460 kJ/day according to the experiment (P<0.01). An experiment conducted with a shorter duration of fasting (16 h) indicated that FHP values are higher than those obtained over at least 24 h of fasting. Our values are similar to those obtained previously on fatter and slow-growing birds, even though the comparison is difficult since measurement conditions and methodologies have changed during the last 30 years. The FHP values obtained in our trials represent a basis for energy nutrition of modern broilers.

Digestibility is a key parameter in the evaluation of feeds; however, the measurements on animals require heavy experimental trials, which are hardly feasible when large numbers of determinations are required – for example, in genetic studies. This experiment aimed at investigating the possibility to predict digestibility from NIRS spectra measured on faeces. A total of 196 samples were available from a digestibility experiment investigating the effects of age and genetic background of Large White pigs fed the same diet, rich in fibre (NDF=21.4% DM). Digestibility of dry matter (dDM), organic matter (dOM), nitrogen content (dN), energy (dE) and apparent digestible energy content (ADE) were calculated, as well as total N content of faeces (N). The faeces samples were submitted to reflectance NIRS analysis after freeze-drying and grinding. Calibration errors and validation errors were, respectively, 0.08 and 0.13% DM for total N in faeces, 0.97% and 1.08% for dDM, 0.79% and 1.04% for dOM, 1.04% and 1.47% for dN, 0.87% and 1.12% for dE and 167 and 213 kJ/kg DM for ADE. These results indicate that NIRS can account for digestibility differences due to animal factors, with an acceptable accuracy. NIRS appears to be a promising tool for large-scale evaluations of digestibility. It could also be used for the study of digestibility of different feeds, after appropriate calibration based on a wide range of feed types.

In the present study, oocytes retrieved from cross bred Karan Fries cows by ovum pick-up technique were graded into Group 1 and Group 2, based on the morphological appearance of the individual cumulus–oocyte complexes (COCs). To analyze whether the developmental potential of the COCs bears a relation to morphological appearance, relative expression of a panel of genes associated with; (a) cumulus–oocyte interaction (Cx43, Cx37, GDF9 and BMP15), (b) fertilization (ZP2 and ZP3), (c) embryonic development (HSF1, ZAR1 and bFGF) and (d) apoptosis and survival (BAX, BID and BCL-XL, MCL-1, respectively) was studied at two stages: germinal vesicle (GV) stage and after in vitro maturation. The competence was further corroborated by evaluating the embryonic progression of the presumed zygotes obtained from fertilization of the graded COCs. The gene expression profile and development rate in pooled A and B grade (Group 1) COCs and pooled C and D grade (Group 2) COCs were determined and compared according to the original grades. The results of the study demonstrated that the morphologically characterized Group 2 COCs showed significantly (P<0.05) lower expression for most of the genes related to cumulus–oocyte interplay, fertilization and embryonic development, both at GV stage as well as after maturation. Group 1 COCs also showed greater expression of anti-apoptotic genes (BCL-XL and MCL1) both at GV stage and after maturation, while pro-apoptotic genes (BAX and BID) showed significantly (P<0.05) elevated expression in poor quality COCs at both the stages. The cleavage rate in Group 1 COCs was significantly higher than that of Group 2 (74.46±7.06 v. 31.57±5.32%). The development of the presumed zygotes in Group 2 oocytes proceeded up to 8- to 16-cell stages only, while in Group 1 it progressed up to morulae (35.38±7.11%) and blastocyst stages (9.70±3.15%), indicating their better developmental potential.

Selection of animals for improved feed efficiency can affect sustainability of animal production because the most efficient animals may face difficulties coping with challenges. The objective of this study was to determine the effects of an inflammatory challenge (using an intravenous injection of complete Freund’s adjuvant – CFA) in piglets from two lines of pigs divergently selected during the fattening period for a low (RFI−) or a high (RFI+) residual feed intake (RFI; difference between actual feed intake and theoretical feed requirements). Nitrogen and energy balances (including heat production – HP – and its components: activity-related HP – AHP, thermic effect of feeding, and resting HP) were measured individually in thirteen 20-kg BW castrated male piglets (six and seven from RFI+ and RFI− line, respectively) fed at the same level (1.72 MJ ME/kg BW0.60 per day) from 3 days before to 3 days after CFA injection. Dynamics of dietary U-13C-glucose oxidation were estimated from measurements of 13CO2 production on the day before and 3 days after the CFA injection. Oxidation of dietary nutrients and lipogenesis were calculated based on HP and O2 consumption and CO2 production. The data were analyzed as repeated measurements within piglets in a mixed model. Before CFA injection, RFI− piglets had a lower resting energy expenditure than RFI+ piglets, which tended to increase energy retention because of a higher energy retention as fat. The CFA injection did not affect feed intake from the day following CFA injection onwards but it increased energy retention (P=0.04). Time to recover 50% of 13C from dietary glucose as expired 13CO2 was higher in RFI+ piglets before inducing inflammation but decreased after to the level of RFI− piglets (P<0.01). Oxidation of U-13C-glucose tended to slightly increased in RFI− piglets and to decreased in RFI+ piglets (P=0.10) because of CFA. Additionally, RFI− piglets had a lower respiratory quotient during the 1st day following the CFA injection whereas RFI+ piglets tended to have a higher respiratory quotient. In conclusion, selection for RFI during the fattening period also affected the energy metabolism of pigs during earlier stages of growth. The effects of CFA injection were moderated in both lines but the most efficient animals (RFI−) exhibited a marked re-orientation of nutrients only during the 1st day after CFA, and seemed to recover thereafter, whereas the less efficient piglets expressed a more prolonged alteration of their metabolism.

This experiment compared growth, physiological, and reproductive responses of beef heifers with (MI) or without (CON) access to a creep-feeder, as a manner to stimulate metabolic imprinting while nursing their dams. On day 0, 60 Angus×Hereford heifers were ranked by BW and age (140±3 kg and 68±3 days), and assigned to pairs so all ranking criteria were similar between heifers within each pair. On day 1, pairs were randomly assigned to MI (n=15) or CON (n=15). From day 1 to 51, MI pairs and their dams were allocated to 15 drylot pens where heifers had ad libitum access to a corn-based supplement through a creep-feeder. The CON pairs and their dams were maintained in an adjacent single drylot pen. From day 52 to 111, treatments were managed as a single group on a semiarid range pasture. On day 111, heifers were weaned and allocated to two pastures (one pasture/treatment), receiving hay and a corn-based concentrate until day 326. Heifer BW was recorded before and at the end of the creep-feeding period (day 1 to 51), and on days 112 and 326. On days 0, 51, 111, 187, 261, and 325, jugular blood was collected and real-time ultrasonography for longissimus muscle depth and backfat thickness assessment was performed. Blood was also collected every 10 days from days 113 to 323 for puberty evaluation via plasma progesterone. Liver and subcutaneous fat biopsies were performed on days 51, 111, 261 and 325. Average daily gain was greater (P<0.01) for MI than CON from day 1 to 51, tended (P=0.09) to be greater for CON than MI from day 112 to 326, while BW on day 326 was similar between treatments. On day 51, MI had greater (P⩽0.01) plasma IGF-I and glucose concentrations, as well as mRNA expression of hepatic pyruvate carboxylase and adipose fatty acid synthase than CON. On days 261 and 325, plasma insulin concentrations were greater (P⩽0.03) in CON than MI. Mean mRNA expression of hepatic IGF-I and adipose peroxisome proliferator-activated receptor gamma were greater (P⩽0.05) in MI than CON. No treatment effects were detected for puberty attainment rate. In conclusion, supplementing nursing heifers via creep-feeding for 50 days altered physiological and biochemical variables suggestive of a metabolic imprinting effect, but did not hasten their puberty attainment.

Determination of appropriate nutritional requirements is essential to optimize the productivity and longevity of lactating sows. The current recommendations for requirements do not consider the large variation between animals. Therefore, the aim of this study was to determine the amino acid recommendations for lactating sows using a stochastic modeling approach that integrates population variation and uncertainty of key parameters into establishing nutritional recommendations for lactating sows. The requirement for individual sows was calculated using a factorial approach by adding the requirement for maintenance and milk. The energy balance of the sows was either negative or zero depending on feed intake being a limiting factor. Some parameters in the model were sow-specific and others were population-specific, depending on state of knowledge. Each simulation was for 1000 sows repeated 100 times using Monte Carlo simulation techniques. BW, back fat thickness of the sow, litter size (LS), average litter gain (LG), dietary energy density and feed intake were inputs to the model. The model was tested using results from the literature, and the values were all within ±1 s.d. of the estimated requirements. Simulations were made for a group of low- (LS=10 (s.d.=1), LG=2 kg/day (s.d.=0.6)), medium- (LS=12 (s.d.=1), LG=2.5 kg/day (s.d.=0.6)) and high-producing (LS=14 (s.d.=1), LG=3.5 kg/day (s.d.=0.6)) sows, where the average requirement was the result. In another simulation, the requirements were estimated for each week of lactation. The results were given as the median and s.d. The average daily standardized ileal digestible (SID) protein and lysine requirements for low-, medium- and high-producing sows were 623 (CV=2.5%) and 45.1 (CV=4.8%); 765 (CV=4.9%) and 54.7 (CV=7.0%); and 996 (CV=8.5%) and 70.8 g/day (CV=9.6%), respectively. The SID protein and lysine requirements were lowest at week 1, intermediate at week 2 and 4 and the highest at week 3 of lactation. The model is a valuable tool to develop new feeding strategies by taking into account the variable requirement between groups of sows and changes during lactation. The inclusion of between-sow variation gives information on safety margins when developing new dietary recommendations of amino acids and protein for lactating sows.

Thirty Aberdeen Angus crossbred steers (281±16 kg) were used to test the effect of finishing feeding system on growth performance, meat quality and fatty acid (FA) profile in intramuscular fat. Steers were fed in confinement (forage:concentrate ratio of 50 : 50; DM basis) or with different levels of energy supplementation (0, 0.4, 0.8 and 1.2% BW) at pasture (Avena strigosa Schreb and Lolium multiflorum L.). There were no differences between treatments for ADG (average=1.60 kg/day), hot carcass weight (HCW) (average=229 kg) and subcutaneous fat depth (average=3 mm). Dressing % (P=0.06; tendency) and carcass ADG (P=0.02) linearly increased with level of supplementation for pasture steers. No differences were observed between treatments for tenderness, marbling, pH, color b*, or cooking loss and drip loss in samples of Longissimus dorsi. However L* increased linearly (P=0.05) with level of supplementation. The concentrations of myristic, palmitic, estearic and linoleic FA did not differ among treatments. The concentration of n-3 FA increased (P<0.001) in steers at pasture compared with confinement, but n-6 FA concentrations did not differ between feeding system. Supplementation up to 0.4% BW increase (P<0.001) conjugated linoleic acid (CLA) and linolenic FA concentrations in intramuscular fat when compared with confinement. The level of supplementation on pasture linearly decreased (P<0.001) n-3 and CLA and linearly increased (P=0.001) the n-6 : n-3 ratio. Finishing of steers grazing winter pasture with energy supplementation or in confinement fed a medium-concentrate diet did not affect meat quality (tenderness, marbling, parameter b* on the CIE L*a*b* scale, cooking and drip losses) except for a* and L*. However, intramuscular fat of animals finished at pasture with moderate level of supplementation compared to animals fed in confinement had greater concentration of CLA, linolenic, and n-3, and lower n-6 : n-3 in intramuscular fat.

Many feeding trials have been conducted to quantify enteric methane (CH4) production in ruminants. Although a relationship between diet composition, rumen fermentation and CH4 production is generally accepted, the efforts to quantify this relationship within the same experiment remain scarce. In the present study, a data set was compiled from the results of three intensive respiration chamber trials with lactating rumen and intestinal fistulated Holstein cows, including measurements of rumen and intestinal digestion, rumen fermentation parameters and CH4 production. Two approaches were used to calculate CH4 from observations: (1) a rumen organic matter (OM) balance was derived from OM intake and duodenal organic matter flow (DOM) distinguishing various nutrients and (2) a rumen carbon balance was derived from carbon intake and duodenal carbon flow (DCARB). Duodenal flow was corrected for endogenous matter, and contribution of fermentation in the large intestine was accounted for. Hydrogen (H2) arising from fermentation was calculated using the fermentation pattern measured in rumen fluid. CH4 was calculated from H2 production corrected for H2 use with biohydrogenation of fatty acids. The DOM model overestimated CH4/kg dry matter intake (DMI) by 6.1% (R2=0.36) and the DCARB model underestimated CH4/kg DMI by 0.4% (R2=0.43). A stepwise regression of the difference between measured and calculated daily CH4 production was conducted to examine explanations for the deviance. Dietary carbohydrate composition and rumen carbohydrate digestion were the main sources of inaccuracies for both models. Furthermore, differences were related to rumen ammonia concentration with the DOM model and to rumen pH and dietary fat with the DCARB model. Adding these parameters to the models and performing a multiple regression against observed daily CH4 production resulted in R2 of 0.66 and 0.72 for DOM and DCARB models, respectively. The diurnal pattern of CH4 production followed that of rumen volatile fatty acid (VFA) concentration and the CH4 to CO2 production ratio, but was inverse to rumen pH and the rumen hydrogen balance calculated from 4×(acetate+butyrate)/2×(propionate+valerate). In conclusion, the amount of feed fermented was the most important factor determining variations in CH4 production between animals, diets and during the day. Interactions between feed components, VFA absorption rates and variation between animals seemed to be factors that were complicating the accurate prediction of CH4. Using a ruminal carbon balance appeared to predict CH4 production just as well as calculations based on rumen digestion of individual nutrients.

Measurements of respiratory exchanges in genuine exercise conditions are undoubtedly of interest to further define the energy needs of endurance horses. However, the equine K4b2, the gas exchanges portable device validated for equines, has not been used in Arabian endurance horses yet. Therefore, the objective of this study was to implement field cardio-respiratory measurements in such horses using the equine K4b2 in order to assess energy expenditure (EE). Measurements of heart rate (HR), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory frequency (RF), tidal volume (VT) and minute expired volume (VE) were carried out at rest and during a 20-min submaximal incremental field exercise in five trained Arabian endurance horses equipped with the K4b2 system. The relationship between HR and VO2 was determined for each horse. EE of the exercise session was calculated from direct VO2 measurements and individual HR-VO2 regression. Out of the five horses, four tolerated the equipment. Respiratory and metabolic variables at rest and during exercise, as well as EE measured at the different gaits, were consistent with reported values in exercising horses: VO2 ranged from 4.8 to 54.1 ml/min per kg from rest to canter, respectively, and EE from 82 to 1095 J/min per kg BW. The 20-min exercise session EE accounted for 6258 and 6332 J from direct VO2 measurements and individual HR-VO2 regression, respectively, which did not differ significantly. Providing an adaptation period and several technical adjustments, the present equine K4b2 could be used to assess EE in Arabian endurance horses in a controlled environment. The prediction of EE from the individual VO2–HR relationship might be an alternative method to evaluate EE when VO2 measurements are not possible.

The aim of this study was to investigate the metabolic and biochemical changes in plasma that occur in the reproductive rabbit doe close to the parturition, as well as if the number of offspring affects the metabolism and the health status of the doe. At −3, 4 and 12 days from parturition (–D3, D4, and D12, respectively) nine rabbit does at their third parity from a commercial hybrid line (HYPLUS PS 19) selected for high prolificacy were weighted and blood was collected for a wide inflammometabolic profile. According to the number of offspring the does were retrospectively divided in two groups: high litter size group (HI; n=5) and low litter size group (LO; n=4). BW was higher (P<0.01) at –D3 and had the lowest values at D4. At D12, the BW was lower (P<0.05) in LO compared with HI. Several metabolites significantly changed from dry to lactation period. Glucose and cholesterol had the lowest levels at –D3; non-esterified fatty acid (NEFA) and aspartate aminotransferase had the highest values before parturition (P<0.05); creatinine and β-hydroxybutyrate (BHBA) were higher at –D3 with respect to D4 (P<0.05). The lowest value of paraoxonase was observed in does at –D3 (P<0.05), whereas at this time ceruloplasmin and total bilirubin had the highest concentration (P<0.05). The differences for blood profile parameters between does grouped according to litter size were mainly evident before parturition (–D3). In particular, BHBA, NEFA and total bilirubin had higher concentrations (P<0.05) in HI v. LO group, whereas albumin and PON were lower in HI group (P<0.01). After parturition there were no significant differences for the metabolic parameters between the two groups. The results show that for reproductive rabbit doe the last days of gestation are very stressful from a metabolic and inflammatory point of view. The genetic selection of does for higher litter size has increased their ability to mobilize body reserves in order to guarantee the nutrients to a high number of kits. This exposes them to a more severe metabolic and inflammatory challenge during the transition period. Consequently, feeding and managerial strategies for high prolificacy periparturient rabbit does should be revised.

Crossbred pigs (n=720; average age=28±3 days and weight=9.5±0.3 kg) were used in a 20-day trial in order to determine the influence of phosphorus (P) source and various doses of pharmacological zinc (Zn) on growth performance, plasma minerals and mineral digestibility. Pigs (five intact males and five females per pen) were randomly allotted to treatments in a 3×3 factorial arrangement with three sources of dietary P (4.5 g/kg digestible P, 4.5 g/kg digestible P plus 2500 phytase units (FTU)/kg, or 5.5 g/kg digestible P) and three dietary levels of supplemental Zn (0, 1750 or 3500 mg/kg) from ZnO (82% Zn) with eight pens per treatment. Diets were formulated to exceed all nutrient requirements, including calcium (Ca), P and Zn from day 0 to 20. Zn supplementation increased (quadratic P<0.05) average daily feed intake. There was a significant Zn level×P source interaction on average daily gain and feed conversion ratio (FCR). Pigs fed 4.5 g/kg digestible P without or with 2500 FTU/kg phytase gained more per day (quadratic P<0.05) and had better FCR (quadratic P<0.05) when they were fed 1750 mg/kg supplemental Zn. However, pigs fed 5.5 g/kg digestible P gained more per day (linear P<0.05) and were more efficient (linear P<0.05) when they were fed 3500 mg/kg supplemental Zn. Plasma Zn and Zn digestibility increased (linear P<0.05) as pharmacological Zn supplementation increased from 0 to 3500 mg/kg, irrespective of P source. However, Ca, P, sodium (Na), potassium (K) and copper (Cu) digestibility were reduced (P<0.05) as pharmacological Zn supplementation increased, and this was mitigated or exacerbated by the supplementation of 5.5 g/kg digestible P or phytase. In conclusion, increasing the dietary inclusion of pharmacological Zn may impact growth performance in young pigs through the interaction with minerals such as Ca, P, Na and K. Pharmacological Zn may reduce Na or K digestibility and indirectly reduce water secretion into the lumen, resulting in an increase in faecal dry matter as pharmacological Zn supplementation in the diet increased.

Cobalamin (CBL), the biologically active form of vitamin B12, and its analogs, are produced by bacteria only if cobalt supply is adequate. The analogs differ generally by the nucleotide moiety of the molecule. In CBL, 5,6-dimethylbenzimidazole (5,6-DMB) is the base in the nucleotide moiety. The present study aimed to determine if a supplement of 5,6-DMB could increase utilization of dietary cobalt for synthesis of CBL and change ruminal fermentation, nutrient digestibility, omasal flow of nutrients and ruminal protozoa counts. Eight ruminally cannulated multiparous Holstein cows (mean±standard deviation=238±21 days in milk and 736±47 kg of BW) were used in a crossover design. Cows were randomly assigned to a daily supplement of a gelatin capsule containing 1.5 g of 5,6-DMB via the rumen cannula or no supplement. Each period lasted 29 days and consisted of 21 days for treatment adaptation and 8 days for data and samples collection. Five corrinoids, CBL and four cobamides were detected in the total mixed ration and the omasal digesta from both treatments. The dietary supplement of 5,6-DMB increased (P=0.02) apparent ruminal synthesis of CBL from 14.6 to 19.6 (s.e.m. 0.8) mg/day but had no effect (P>0.1) on apparent ruminal synthesis of the four analogs. The supplement of 5,6-DMB had no effect (P>0.1) on milk production and composition, or on protozoal count, ruminal pH and concentrations of volatile fatty acids and ammonia nitrogen in rumen content. The supplement had also no effect (P>0.1) on intake, omasal flow and apparent ruminal digestibility of dry matter, organic matter, NDF, ADF and nitrogenous fractions. Plasma concentration of CBL was not affected by treatments (P=0.98). Providing a preformed part of the CBL molecule, that is, 5,6-DMB, increased by 34% the apparent ruminal synthesis of CBL by ruminal bacteria but had no effect on ruminal fermentation or protozoa count and it was not sufficient to increase plasma concentrations of the vitamin. Even though the efficiency of cobalt utilization for apparent synthesis of CBL was increased from 2.0% to 2.7% by the 5,6-DMB supplement, this improved efficiency was still very low. Further research is needed to identify the factors affecting efficiency of utilization of cobalt for synthesis of CBL by the bacterial populations in rumen.

A proteomic approach was used to investigate the effects of the processing method of corn grain and soybean meal on the milk protein expression profile in lactating dairy cows. A total of 12 multiparous Holstein dairy cows were used in a 4×4 Latin square design with a 2×2 factorial arrangement. The primary factors examined were corn (finely ground (FGC) v. steam-flaked (SFC)) and soybean meal (solvent-extracted (SSBM) v. heat-treated (HSBM)), which were used to formulate four diets with the same basal ingredient: 27% FGC and 9% SSBM; 27% SFC and 9% SSBM; 27% FGC and 9% HSBM; and 27% SFC and 9% HSBM. Each period lasted for 21 days. Milk samples were collected on days 18, 19 and 20 of each period. Changes in the milk proteins were assessed by two-dimensional (2D) electrophoresis and ImageMaster 2D Platinum 6.0 software. A total of 13 spots displayed variations in protein spot abundance according to the statistical analysis. These spots were identified by a matrix-assisted laser desorption/ionization-time of flight/time of flight MS. According to the gels, the relative abundance of αs2-casein (CN) fragments was higher in the cows fed the SFC-HSBM than that for SFC-SSBM, whereas β-CN, α-lactalbumin and zinc-alpha-2-glycoprotein fragments were down-regulated in HSBM-fed cows. The relative decrease of β-CN expression was validated by western blot and agreed with the MS data. These results suggested that the method used to process soybean meal modified the synthesis and secretion of milk proteins in lactating dairy cows’ mammary glands.

In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing method to reduce the particulate matter loss during rinsing and on quantifying the particulate matter loss that occurs during incubation in the rumen itself. To quantify particulate matter loss during incubation, loss of small particles during the in situ incubation was studied using undegradable silica with different particle sizes. Particulate matter loss during incubation was limited to particles smaller than ~40 μm with a mean fractional particulate matter loss rate of 0.035 h−1 (first experiment) and 0.073 h−1 (second experiment) and an undegradable fraction of 0.001 and 0.050, respectively. In the second experiment, the fractional particulate matter loss rate after rinsing in a water bath at 50 strokes per minute (s.p.m.) (0.215 h−1) and the undegradable fraction at 20 s.p.m. (0.461) were significantly larger than that upon incubation in the rumen, whereas the fractional particulate matter loss rate (0.140 and 0.087 h−1, respectively) and the undegradable fraction (0.330 and 0.075, respectively) after rinsing at 30 and 40 s.p.m. did not differ with that upon rumen incubation. This new approach was applied to estimate the in situ fractional degradation rate of insoluble organic matter (OM) and insoluble nitrogen (N) in three different wheat yeast concentrates (WYC). These WYC were characterised by a high fraction of small particles and estimating their fractional degradation rate was not possible using the traditional washing machine rinsing method. The new rinsing method increased the mean non-washout fraction of OM and N in these products from 0.113 and 0.084 (washing machine method) to 0.670 and 0.782, respectively. The mean effective degradation (ED) without correction for particulate matter loss of OM and of N was 0.714 and 0.601, respectively, and significant differences were observed between the WYC products. Applying the correction for particulate matter loss reduced the mean ED of OM to 0.676 (30 s.p.m.) and 0.477 (40 s.p.m.), and reduced the mean ED of N to 0.475 (30 s.p.m.) and 0.328 (40 s.p.m.). These marked reductions in fractional degradation rate upon correction for small particulate matter loss emphasised the pronounced effect of correction for undegraded particulate matter loss on the fractional disappearance rates of OM and N in WYC products.

It is essential to quantify the potential of tropical grasslands to allow significant feed efficiency for grazing livestock in controlled conditions such as at pasture. We conducted a quantitative analysis of published studies reporting the experimental results of average daily gains (ADG) and diet characteristics obtained specifically under grazing conditions (17 publications and 41 experiments), which have been less studied compared with controlled conditions in stalls. The database was analyzed to determine the average and range of values obtained for ADG (g/kg BW), dry matter digestibility, intake (DMI) and digestible DMI (DDMI, g/kg BW) and feed conversion efficiencies (FCE), as well as to predict the response of these parameters to the main strategies investigated in the literature – that is, mainly the stocking rate (SR) and the concentrate intake (CI). The ADG reached 1.2 kg BW per day and was directly linked to DDMI (ADG=−1.63+0.42 DDMI −0.0084 DDMI2, n=90, r.m.s.e=0.584, R2=0.93). The DDMI, which was representative of the nutrient input, was driven mainly by DMI rather than dry matter digestibility, whereas these two parameters did not correlate (r=0.068, P=0.56). The average global FCE (0.11 g ADG/g DDMI) showed a greater association with the metabolic FCE (0.17 g ADG/g DMI) than the digestive FCE (0.62). The CI (g DM/kg BW) increased ADG (ADG=2376+CI 56.1, n=16, r.m.s.e.=441, R2=0.95). The SR expressed as kg BW/ha decreased the individual ADG by 1.19 g/kg BW per additional ton of BW/ha, whereas the global ADG calculated per ha increased by 0.57 per additional ton BW/ha. When the SR was expressed as kg BW/ton DM and per ha rather than as kg BW/ha, the impact on the individual ADG decreased by 0.18 or 0.86 g per additional ton BW/ha, depending on the initial BW of the cattle. These results provide a better view of the potential performance and feeding of cattle in tropical grasslands. The results provide an improved quantification of the relationships between diet and performance, as well as the overall quantitative impact of SR and supplementation.

The objective was to study the effect of maternal supplementation with a yeast cell wall-based product containing a mannan-rich fraction (MRF) during gestation and lactation on piglet intestinal gene expression. First parity sows were fed experimental gestation and lactation diets with or without MRF (900 mg/kg). After farrowing, piglets were fostered within treatment, as necessary. Sow and litter production performance data were collected until weaning. On day 10 post farrowing, jejunum samples from piglets were collected for gene expression analysis using the Affymetrix Porcine GeneChip array. Most performance parameters did not differ between the treatments. However, protein (P<0.01), total solids less fat (P<0.03) and the concentration of immunoglobulin G (IgG) in milk were greater (P<0.05) in the MRF-supplemented group. Gene expression results using hierarchical clustering revealed an overall dietary effect. Further analysis elucidated activation of pathways involved in tissue development, functioning and immunity, as well as greater cell proliferation and less migration of cells in the jejunum tissue. In conclusion, feeding the sow MRF during pregnancy and lactation was an effective nutritional strategy to bolster colostrum and milk IgG that are essential for development of piglet immune system and gut. In addition, the gene expression patterns affected by the passive immunity transfer showed indicators that could benefit animal performance long term.

Selection programs have enabled broiler chickens to gain muscle mass without similar enlargement of the cardiovascular and respiratory systems that are essential for thermoregulatory efficiency. Meat-type chickens cope with high ambient temperature by reducing feed intake and growth during chronic and moderate heat exposure. In case of acute heat exposure, a dramatic increase in morbidity and mortality can occur. In order to alleviate heat stress in the long term, research has recently focused on early thermal manipulation. Aimed at stimulation of long-term thermotolerance, the thermal manipulation of embryos is a method based on fine tuning of incubation conditions, taking into account the level and duration of increases in temperature and relative humidity during a critical period of embryogenesis. The consequences of thermal manipulation on the performance and meat quality of broiler chickens have been explored to ensure the potential application of this strategy. The physiological basis of the method is the induction of epigenetic and metabolic mechanisms that control body temperature in the long term. Early thermal manipulation can enhance poultry resistance to environmental changes without much effect on growth performance. This review presents the main strategies of early heat exposure and the physiological concepts on which these methods were based. The cellular mechanisms potentially underlying the adaptive response are discussed as well as the potential interest of thermal manipulation of embryos for poultry production.

The present study was undertaken to examine the effect of cow genetic merit on enteric methane (CH4) emission rate. The study used a data set from 32 respiration calorimeter studies undertaken at this Institute between 1992 and 2010, with all studies involving lactating Holstein-Friesian dairy cows. Cow genetic merit was defined as either profit index (PIN) or profitable lifetime index (PLI), with these two United Kingdom genetic indexes expressing the expected improvement in profit associated with an individual cow, compared with the population average. While PIN is based solely on milk production, PLI includes milk production and a number of other functional traits including health, fertility and longevity. The data set had a large range in PIN (n=736 records, −£30 to +£63) and PLI (n=548 records, −£131 to +£184), days in milk (18 to 354), energy corrected milk yield (16.0 to 45.6 kg/day) and CH4 emission (138 to 598 g/day). The effect of cow genetic merit (PIN or PLI) was evaluated using ANOVA and linear mixed modelling techniques after removing the effects of a number of animal and diet factors. The ANOVA was undertaken by dividing each data set of PIN and PLI into three sub-groups (PIN:<£3, £3 to £15 and >£15, PLI:<£23, £23 to £67 and >£67) with these being categorised as low, medium and high genetic merit. Within the PIN and PLI data sets there was no significant differences among the three sub-groups in terms of CH4 emission per kg feed intake or per kg energy corrected milk yield, or CH4 energy (CH4-E) output as a proportion of energy intake. Linear regression using the whole PIN and PLI data sets also demonstrated that there was no significant relationship between either PIN or PLI, and CH4 emission per kg of feed intake or CH4-E output as a proportion of energy intake. These results indicate that cow genetic merit (PIN or PLI) has little effect on enteric CH4 emissions as a proportion of feed intake. Instead enteric CH4 production may mainly relate to total feed intake and dietary nutrient composition.