Balancing rations for essential amino acids (AA) to improve efficiency of utilisation (Eff) of N requires a better knowledge of AA use by different tissues under various nutritional conditions. Effects of infusion of AA (AA(inf)) and glucose (Glc(inf)), in a 2x2 factorial arrangement, were tested using 5 cows in a 4x4 Latin Square plus one cow. At the end of each period, splanchnic, mammary and other peripheral tissue metabolisms of AA were measured. There was no AA(inf)xGlc(inf) interaction on most of the measured parameters. Milk protein yield (MPY) increased with AA(inf) and Glc(inf). With AA(inf), catabolism by portal-drained viscera (PDV) and mammary gland of group 2 AA (Ile, Leu, Lys, and Val) increased leading to a decreased Eff. In contrast, with Glc(inf), liver removal of His + Met + Phe (HMP) decreased, improving their Eff.
The present study aimed to evaluate the use of dual-energy x-ray absorptiometry (DXA) to predict the physical and chemical composition of beef carcass. Fifteen Nellore heifers with weight of 263.66 +/- 62 kg and a mean age of 11 months were fasted for 16 hours and slaughtered. The carcass was divided lengthwise and cooled at 4 degrees C for 24 hours. The left half-carcass of each animal was weighed and scanned by Dual-Energy X-ray Absorptiometry, producing measurements of the total tissue (TTM), DXA fat, DXA lean mass, bone mineral content (BMC) and bone mass density (BMD, kg/cm(2)). Regression analysis to estimate the carcass physical and chemical composition from DXA measurements showed that DXA measurements accurately predicted muscle (r=0.99), fat (kg; r=0.82), and bone (kg; r=0.90) mass (P<0.01). The ether extract (EE) content was significantly correlated with DXA fat of the carcass (P<0.01; r=0.99). Dual-energy x-ray absorptiometry can be used to predict carcass composition, and there is potential for it to be used in carcass evaluation and classification systems.
Comparing heat production after ad libitum (ADLIB) and restricted (RESTRICT) feeding periods may offer insight into how residual feed intake (RFI) groups change their energy requirements based on previous feeding levels. In this study, the authors sought to explain the efficiency changes of high- and low-RFI steers after feed restriction. To determine RFI classification, 56 Angus-cross steers with initial body weight (BW) of 350 ± 28.7 kg were individually housed, offered ad libitum access to a total mixed ration, and daily intakes were recorded for 56 d. RFI was defined as the residual of the regression of dry matter intake on mid-test BW0.75 and average daily gain. High- and low-RFI groups were defined as >0.5 SD above or below the mean of zero, respectively. Fourteen steers from each high and low groups (n = 28) were selected for the subsequent 56-d RESTRICT period. During the RESTRICT period, intake was restricted to 75% of previous ad libitum intake on a BW0.75 basis, and all other conditions remained constant. After the RESTRICT period, both RFI groups had decreased maintenance energy requirements. However, the low-RFI group decreased maintenance energy requirements by 32% on a BW0.75 basis, more (P < 0.05) than the high-RFI group decreased maintenance requirements (18%). Thus, the low-RFI steers remained more efficient after a period of feed restriction. We conclude that feed restriction decreases maintenance energy requirement in both high- and low-RFI groups that are restricted to the same degree.
The objective of this study was to evaluate the physical and chemical composition of the 9th to 11th rib section with other rib sections in Nellore cattle. Fourteen Nellore bulls (average age = 13 mo and carcass weight = 259 kg) were used. The six ribs sections were: 9th to 11th rib section (HH); prime rib section (PR; 6th to 12th rib section); tip of the ribs corresponding to HH (THH); tip of the ribs corresponding to the PR (TPR); HH plus THH (HH+THH) and PR plus TPR (PR+TPR). Each section was separated into meat + fat and bones. Water, ash, crude protein (CP) and ether extract (EE) contents were determined in all rib sections. The physical and chemical composition of all rib sections were compared with the HH composition by using the Dunnett's test. All sections, except the THH and TPR, presented the physical composition similar to the HH. However, ash and EE contents in PR and the water, ash and CP contents in HH+THH were similar to the HH composition. In conclusion, PR, HH+THH and PR+TPR physical compositions were similar to HH. However, none of the sections evaluated in the current study presented similar chemical composition to the HH.
Two experiments were conducted to test the hypothesis that both the degree and duration of heating that is applied will affect the concentration of metabolizable energy (ME) and the standardized ileal digestibility (SID) of amino acids (AA) in double-low rapeseed meal (RSM) fed to growing pigs. Nine treatments were prepared using a conventional RSM that was either not autoclaved or autoclaved following one of 8 treatments: 110 degrees C for 15 or 30 min or 150 degrees C for 3, 6, 9, 12, 15, or 18 min. In both experiments, 20 barrows were assigned to a replicated 10 treatment x 4 period Youden square design. There were no effects of autoclaving at 110 degrees C on ME or on SID of AA in RSM but both ME and SID of AA in RSM were less (P<0.01) if RSM was autoclaved at 150 degrees C compared with 110 degrees C. At 150 degrees C, there were decreases (quadratic, P<0.05) in both ME and SID of AA as heating time increased. In conclusion, autoclaving at 110 degrees C did not affect ME or SID of AA in double-low RSM, but autoclaving at 150 degrees C reduced both ME and SID of AA, and the negative effects increased as heating time increased.
Pigs deviate from their circadian feeding rhythm as a response to environmental influences, like heat stress and stocking density. Misalignment of feeding rhythm and the endogenous circadian clock may increase fat deposition, as was shown in humans and rodents. To investigate the effect of circadian misalignment on energy balance of growing pigs, twelve groups of five male pigs were fed during the day (10:00-18:00 h; diurnal feeding: DF) or night (22:00-06:00 h; nocturnal feeding: NF). Paired feeding was applied to ensure equal gross energy intake between treatments. Energy balances and heat partitioning were measured and calculated. Heat production was 3% lower for NF-pigs than DF-pigs (P<0.026) increasing energy retention as fat with 7% in NF-pigs (P=0.050). Nocturnal-fed pigs were less active than DF-pigs during the feeding period, but more active during the fasting period (P<0.05). Methane production was 30% greater in NF pigs than DF pigs. In conclusion, circadian misalignment induced by nocturnal feeding reduces heat production, and consequently increases fat deposition in growing pigs.
During force-feeding period, Mule ducks received increasing amounts of feed to force steatosis of the liver. The intensive lipogenesis is associated with high amount of energy to export as heat. The effects of ambient temperature on heat production and energy metabolism were tested on Mule ducks housed in an open-circuit respiration chamber. The metabolizable energy intake tended to be lower when ambient temperature was higher than 22 degrees C whereas total heat production was lower when ambient temperature was lower than 15 degrees C or higher than 22 degrees C, because ducks have reached their maximal ability of heat vaporization even at the lowest ambient temperature. Alternating periods of intense lipogenesis after the meal with periods of resting metabolism helps the ducks to adapt to high ambient temperature.
The data of fifty non-pregnant and non-lactating mature Pelibuey ewes were used to study the relationship between body condition score (BCS) and body fat depots. The animals were slaughtered; before slaughter, and BCS were measure after feed and water deprivation for 24 h. At slaughter internal fat (IF, internal adipose tissue) was dissected, weighed and grouped as mesenteric (MF), omental (OF) and pelvic fat (PF). After refrigeration (1 degrees C during 24 h), the left half of the carcass was completely dissected into subcutaneous and intermuscular fat (carcass fat, CF). The relationships between BCS and with body fat depots were investigated using regression analysis. All regression equations between body fat depots with BW and BCS were significant (P<0.0001), the r(2) ranged from 0.62 for PF and MF, to 0.81 for CF when BW was used as independent variable; meanwhile when BCS was used the r(2) ranged from 0.67 for PF to 0.89 for MF. The regression equation for estimating total body fat (TBF) from BCS were TBF (kg)=-2.64 (+/- 0.911) + 4.29 (+/- 0.302) x BCS (r(2)=0.89; RSD=1.916; P<0.0001 and n=28). These results indicated that BCS could be used as a predictor of the main body fat reserves in Pelibuey ewes.
The objective of the present study was to evaluate the relationship between body weight (BW) at slaughter (SBW) and empty body weight (EBW) and develop equations to estimate EBW in suckling hair lambs from different genotypes (Pelibuey and Katahdin), sexes (males and females) and litter sizes (single or double). The experiment was conducted with 66 lambs, 39 Pelibuey and 27 Katahdin, 37 males and 29 females; 30 of single birth and 36 of double birth. The effects of the genotype, sex and litter size were tested. The correlation coefficient between the SBW and EBW was 0.98 (P<0.001). It was observed that genotype and sex had no effect (P>0.05) on the relationship of SBW and EBW; however, the litter size did have influence (P<0.05) SBW and EBW relationship. The slopes of the equations were similar (P>0.001). Finally, an equation without intercept was proposed: EBW = 0.89 (+/- 0.003**) x SBW (R-2=0.98, MSE=0.119, RSD=0.345 and n=66). The present study indicates weight of gastrointestinal content was 11% of SBW of suckling hair lambs. The genotype, sex and litter size had no effect on this proportion.
The objective of this study was to evaluate the effect of Ammonia Fiber Expansion (AFEX) treated wheat straw pellets and a specifically selected recombinant fibrolytic enzyme on the feed digestion and performance of lambs. Eight wethers and 60 lambs (n=15/diet, 8 rams and 7 ewes) were used in a replicated 4x4 Latin square design digestibility study, and a complete randomized growth performance study, respectively. Four treatment diets were arranged in a 2x2 factorial structure with AFEX wheat straw [0 or 30% AFEX straw pellets of diet dry matter (DM) basis replacing alfalfa hay pellets] and fibrolytic enzyme (with or without XYL10C, a beta-1,4- xylanase, from Aspergillus niger) as main factors. Enzyme was applied at 100 mg/kg of diet DM 22 h before feeding. Digestibility of DM did not differ (P>0.10) among treatments, but digestibility of crude protein (CP) reduced (P=0.001), and digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased (P<0.05) when AFEX replaced alfalfa. Replacing alfalfa with AFEX wheat straw increased DM intake (DMI, P=0.003), but average daily gain (ADG) was not improved (P=0.51), and consequently gain:feed (G:F) was reduced (P=0.04). XYL10C did not affect (P>0.10) digestibility, intake, ADG, or G:F, and neither AFEX or XYL10C affected (P>0.10) carcass traits. These findings indicate that AFEX treated wheat straw pellets was a suitable option for partial replacement of alfalfa hay pellets for sheep.
Difference in amino acid (AA) absorption kinetics among different protein sources may affect the metabolism and utilisation of AA. The aim was to determine postprandial AA appearance in the portal blood of growing pigs as influenced by protein source. Seven pigs (18 kg) were fitted with a jugular vein catheter and fed the experimental diets (wheat, soybean meal, enzyme-treated soybean meal, hydrothermally treated rapeseed meal, casein and hydrolysed casein). Blood samples were collected at -30, 30, 60, 90, 120, 180 and 360 minutes relative to feeding and analysed for free AA in plasma. Except for the wheat diet, all the other protein sources had an increase (P<0.001) in the plasma AA concentration 60 minutes after feeding. The plasma AA concentration was higher (P<0.001) for high-protein sources (casein, hydrolysed casein and enzyme-treated soybean meal) compared with wheat. There were no differences between casein and hydrolysed casein except for 180 minutes after feeding, where the AA concentration in plasma was lower for casein compared with hydrolysed casein. The plasma AA concentration was lower for soybean meal compared with enzyme-treated soybean meal at 60 and 120 minutes after feeding. There were no differences between hydrothermally treated rapeseed meal and soybean meal. In conclusion, casein, hydrolysed casein and enzyme-treated soybean meal can be regarded as fast protein sources compared with wheat, soybean meal and hydrothermally treated rapeseed meal.
A multi-study analysis was conducted aiming to estimate and validate new equations to predict carcass weight (CW), empty body weight gain (EBG), and retained energy (RE) of Zebu cattle. A database composed of 1,748 observations of bulls, steers, and heifers of different breeds (Zebu, beef crossbred, and dairy crossbred) was used for generating the new equations. The evaluation of new equations was performed using an independent database composed of 137 observations. Validation analyses were performed by using the model evaluation system. We suggest the following equations to estimate CW, EBG, and RE of Zebu cattle: CW (kg) = -11.03 + S + ((0.6094 + G + B) x SBW); EBG = 0.04422 + 1.4664 x CG; RE = 0.08159 x EQEBW(0.75) x CG(0.7768), where S = slaughter plant effect, if commercial = -10.98, if experimental =0; G = gender effect, if steer = 0, if bull = 0.008169 and if heifer = -0.00612; B = genotype effect, if Zebu = 0, if dairy crossbreds = -0.03301 and if beef crossbreds = -0.01595; SBW = shrunk body weight; CG = carcass gain; EQEBW = equivalent empty body weight. Equations accurately and precisely estimated CW, EBG, and RE of Zebu and Zebu-cross cattle in the validation dataset.
Quantitative indicators of formation of substrates-nutrients in the rumen in the process of digestion of feed, transport, metabolism and use of the latter in the process of milk synthesis have been studied. The possibility of predicting not only the amount of metabolizable energy (ME) and nitrogen equivalent, but also the recommendation of the main substrates and essential nutrients that limit biosynthesis is discussed. Based on experimental data, the optimal requirements for the basic substrates in cows [acetate, propionate, amino acids (AA), glucose and long chain fatty acids (LCFA)] to achieve effective bioconversion of feed nutrients into dairy products are estimated. Experimental verification of the efficiency of balancing the ration of highly productive cows, taking into account substrate supply and productive functions of lactating cows, showed that by balancing ration providing the optimal ratio of absorbed substrates, it is possible to increase the efficiency of the use of ME and metabolizable protein for milk formation by 5% and increase milk productivity by 10-15%.
The N use efficiency (NUE) of ruminants is negatively correlated to the natural N-15 enrichment of ruminants' tissues over their diets (Delta(15)Nanimal-diet). The metabolism of rumen bacteria, which strongly discriminates against N-15 utilisation, may contribute to this link but little is known about the role of individual bacteria. In this study, we characterised the Delta N-15 of three metabolically different rumen bacteria, a cellulolytic ammonia-consuming, a hyper-ammonia producing and a proteolytic organism, grown in pure culture with different N sources and levels. The N isotopic signatures significantly changed across the 3 rumen bacteria. Although we failed to observe a higher Delta N-15(bacteria-substrate) when proteolysis and NH3 production was favoured, our results confirm a strong N-15 depletion with the NH3-consuming bacterium. This may suggest that N-15 depleted NH3-consuming bacteria improve the NUE in the rumen.
In the transition from late pregnancy to start of lactation, immune function is compromised in mammals. Immune response to mitogens largely differs among cows, especially in early lactation. The lymphocyte activation might be impaired by the limited availability of energy and nutrients in this critical period. We hypothesized that the lymphocyte proliferation (72 h) is related to their activation (24 h) and to the cow's feed intake, feed efficiency, resting metabolic rate (RMR) and mobilization of body reserves. Seventeen multiparous Holstein cows were studied in weeks -2 and +2 around calving. Zootechnical parameters as well as activation and proliferation of lymphocytes were quantified based on their in vitro oxygen consumption rate and 3-[4,5-dimethyldiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT)-reducing activity, respectively. Cows were classified by their proliferative response postpartum as low (L), medium (M), and high (H) responders. Surprisingly, the differences observed in lymphocyte proliferation were not related to activation, feed intake, feed efficiency (milk yield per unit of intake), RMR and body reserve mobilization. However, L cows had smaller levels of methane emission per unit of milk and per unit of body weight after calving compared to H cows. This is indicative of a lower rumen fermentation intensity. It suggests that, in early lactation, low responders might suffer from a smaller availability of digestible energy to sustain immune response consisting of the shift from activation to proliferation. Therefore, the selection of environmentally friendly low methane emitters could favour cows with weak immune response in the critical period of early lactation.
The aim of this study was to evaluate changes in muscle mitochondrial respirometry in training horses. Fourteen Brazilian Sport Horses were used, ranging between 4 and 6 years old, and beginners in eventing discipline. Muscle samples were obtained by biopsy of the gluteus medius muscle, and collected before and after a treadmill test. The horses were submitted to an incremental velocity test until reaching the speed of 8 m/s, keeping at this speed up to horse's exhaustion. Muscle tissue samples were disclosed and transferred to a maintenance solution - BIOPS, remaining at 4 degrees C until analysis. Mitochondrial respiration was evaluated using a high resolution oxygraph (Oroboros (R)). The results were corrected for time (seconds) / sample weight (mg) and expressed as mean and standard deviation. The paired T-test at 0.05 of probability was used. The maximum mitochondrial respiration was not altered by the exercise up to exhaustion, however, there was an increase in mitochondrial respiration using the pyruvate and malate substrates. Non-mitochondrial respiration increased after the test. There was little change in the mitochondrial physiology of the muscle after the test. The reactions of oxidative enzymes of the gluteus medius muscle increased in horses after treadmill test.
Sphingolipids are well-known modulators of metabolic pathways which may contribute to the metabolic differences between adipose tissues. This study aimed to characterise depot-specific sphingolipid profiles in bovine adipose tissues. Subcutaneous (SCAT) and retroperitoneal adipose tissue (RPAT) samples of 6 Holstein bulls were analysed by a targeted metabolomics approach. Abundance of several sphingolipids were different between the depots. Particularly ceramides associated with insulin resistance were higher abundant in RPAT. Assuming that these signals can be released into the circulation, a higher metabolic activity of RPAT might favour insulin resistance.
The aim of this work was to study mitochondrial function in two Holstein genotypes under different feeding strategies during mid-lactation. Multiparous Holstein cows of New Zealand (HNZ) and North American (NA) origin were assigned to two feeding strategies: maximum pasture intake according to its growth in the grazing area plus an energy-protein concentrate (PMAX) or total mixed ration and one third of the diet offered as pasture (P30). Mitochondrial respiration was measured using Complex I and II substrates and hepatic glucose and glycogen were measured in liver biopsies. Respiration linked to ATP synthesis was affected and state 3 respiration tended to be affected by the interaction between genotype and feeding strategy; both parameters were higher for HNZ cows in the PMAX strategy when using Complex II substrates. Liver glycogen was higher in the PMAX than P30 strategy. Glycogen correlated positively with state 3 and ATP-linked respiration for PMAX cows when succinate was used as substrate, suggesting an association between succinate driven respiration and glucose metabolism.
Energy expenditure of animals has been mainly determined under controlled confined conditions which would do not reflect always the conditions of rangelands cows. Multiparous beef cows (n=25) grazing on two herbage allowances (HA) of Campos grassland (average HA of 8 vs 12 kg dry matter/kg BW; LO vs HI) were used to estimate maintenance energy requirements (MEm) and efficiency use of consumed metabolizable energy (ME) for maintenance (km) in free-range beef cows grazing Campos. Along the annual production cycle, in four periods, cow BW (body weight) and BCS (body condition score), and calf birth weight or milk production and composition, as well as heat production (HP; by the O-2 pulse technique) were recorded to estimate retained energy (RE) and ME intake (MEI). Data were expressed as kJ/kgBW(0.75). Linear regressions of the dependency of HP on MEI (HP = b x MEI + a) for both, cows in negative and positive energy balance and MEm was calculated. Regressions of HP on MEI were high and significant (P<0.001) for both, cows in positive (HP=323 + 0.43 MEI; r(2)=0.84) and negative (HP=176 + 0.61 MEI; r(2)=0.76) energy balance. Thus, MEm for rangeland beef cows varied from 444 to 567 kJ/kg of BW0.75 per d depending on their nutritional status. Nutritional status as well as grazing management should be considered in order to adequate estimate nutritional demands of the suckler beef cow which would allow to improve productive efficiency and environmental sustainability of cow-calf systems.
Various feeds have been identified which are effective in mitigation of noxious gases from ruminant husbandry. This list includes a number of tanniferous plants, the intake of which may, however, be small due to a low palatability and tannins may also adversely affect performance of the animals. Previous studies indicated that hazel leaves contain substantial amounts of tannins and have methane and urinary N mitigation properties, but still seem to be palatable. In the present study, complete energy and N balances were established in 20 dairy cows receiving pellets with increasing hazel leaf proportion in replacement to lucerne. After 14 days of adaptation, faeces and urine were collected over 8 days and gaseous exchange was quantified over 2 days in open circuit respiration chambers. The hazel leaves did not impair feed intake. The proportionate energy losses through faeces increased and those of methane and milk declined linearly and curvilinearly with increasing hazel proportion, respectively (P<0.001). The proportionate energy excretion through urine and heat were not affected. Increasing hazel proportions substantially shifted N excretion from urinary (decline from about 30 to 10% of intake) to faecal N (from <40 to 60%). Non-linear responses were found in relation to N excretion in milk and in body N retention. In conclusion, hazel leaves showed a great potential as palatable feed supplement for sustainable dairy cow nutrition. The relatively low feeding value of hazel leaves has to be compensated by complementary feeds in high-quality diets.
