Level Of Feed Intake Research Articles

Protective effects of edaravone on experimental chronic pancreatitis induced by dibutyltin dichloride in rats

Background/aimsTo investigate the effects of edaravone, a potent free radical scavenger, on dibutyltin dichloride (DBTC)-induced chronic pancreatitis (CP) and pancreatic fibrosis. MethodsMale Sprague–Dawley rats were randomly divided into four groups (n = 16 each): control, DBTC, DBTC + edaravone, and control + edaravone. Edaravone or normal saline at a daily dose of 6 mg/kg body weight was given intraperitoneally from day 5 to day 28 after DBTC administration. On days 14 and 28, the rats were evaluated morphologically and biochemically. The expression of cytokines in pancreas TGF-β, IL-6 and TNF<alpha> was detected using RT-PCR. The activation of nuclear factor (NF)-κB in pancreatic tissue was evaluated by immunostaining and western-blot for NF-κB p65. α-smooth muscle actin (α-SMA) expression was also evaluated by immunostaining and western-blot to investigate the activation of pancreatic stellate cells (PSCs). ResultEdaravone treatment improved the rats' body weight (p < 0.01) and feed intake levels (p < 0.05), improved the histological scores and alleviated the fibrosis of pancreas samples (p < 0.05), as well as markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). The expression of cytokines TGF-β, IL-6 and TNF<alpha> in pancreas of DBTC group was also down-regulated by edaravone after treatment. Edaravone inhibited the activation of NF-κB and PSCs and exhibited protective effects on pancreatic tissue damage in CP. ConclusionsThis antioxidant may be a promising therapeutic intervention for human CP.

Effects of feed intake on enteric methane emissions from sheep fed fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) forages

Published analyses of enteric methane (CH4) emissions from sheep and cattle show an inverse relationship between feed intake and CH4 yield (gCH4/kg dry matter (DM) intake), which suggests opportunities for reducing CH4 emissions from feed eaten and per unit of animal production. Most relationships between feed intake and CH4 yield have been based on animals fed conserved feeds, especially silages and grains. Our research is a series of experiments with fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne; ryegrass) forages fed to sheep at a range of feed intake levels. This study was comprised of four experiments where good quality freshly harvested white clover or ryegrass were fed to sheep over a three-fold range in DM intake, and CH4 emissions were measured in respiration chambers for two consecutive days in each experiment. Measurements were made from 16 sheep in Experiment 1 (fed at 1.6×metabolizable energy requirements for maintenance; MEm), 28 sheep in Experiment 2 (at 0.8 and 2.0×MEm), eight sheep and two measurement periods in Experiment 3 (at 1.6×MEm), and 30 sheep in Experiment 4 (fed at 0.8, 1.2, 1.6, 2.0 and 2.5×MEm). Prior to each experiment, sheep had a 10d acclimatization period to diets. Apparent digestibility was measured over 7d from sheep in Experiments 1, 3 and 4, along with collection of rumen digesta for volatile fatty acid (VFA) determination. Although CH4 yields differed when sheep were fed white clover or ryegrass at similar intakes, the differences were inconsistent and mean values similar across all experiments. This, and a similar structure of all experiments, enabled combined analysis of data from all four experiments using the restricted maximum likelihood (REML) procedure to estimate effects of feed intake level on digestibility, digestible nutrient intake, gas emissions, and VFA concentrations in the rumen. The REML analysis showed that when DM intake increased from 0.40 to 1.60kg/d, the predicted responses were an increase in CH4 production (g/d) of 187% (12.4–35.6g/d; P<0.001), and a decline in CH4 yield of 21% (25.6–20.2g/kg DM intake; P<0.001). High feed intake levels were associated with increased molar proportions (mM of total VFA) of propionate from 0.17 to 0.21 (P=0.038). Single and multiple regressions were completed on the data from all experiments, with organic matter (OM) intake predicting 0.87 of the variation in CH4 production, and molar proportion of propionate predicting 0.60 of the variation in CH4 yield. Increasing feed intakes by 1kg/d of DM reduced CH4 yield by 4.5g/kg DM intake. Plant chemical composition was weakly related to CH4 yield. High intakes of fresh forages will lower CH4 yield from fermentation, but effects of feed composition on CH4 emissions were minor. The interaction between effects of feed intake and rumen function requires further investigation to understand relationships with CH4 emissions.

Meat quality of young Nellore bulls with low and high residual feed intake

Fifty-nine Nellore bulls from low and high residual feed intake (RFI) levels were studied with the objective of evaluating meat quality traits. Animals were slaughtered when ultrasound-measured backfat thickness reached 4mm, and samples of Longissimus were collected. A mixed model including RFI as fixed effect and herd and diet as random effects was used, and least square means were compared by t-test. More efficient animals consumed 0.730kg dry matter/day less than less efficient animals, with similar performance. No significant differences in carcass weight, prime meat cuts proportion, chemical composition, pH, sarcomere length, or color were observed between RFI groups. Shear force, myofibrillar fragmentation index and soluble collagen content were influenced by RFI, with a higher shear force and soluble collagen content and a lower fragmentation index in low RFI animals. Feedlot-finished low RFI young Nellore bulls more efficiently convert feed into meat, presenting carcasses within quality standards.

The Influence of Climate, Soil and Pasture Type on Productivity and Greenhouse Gas Emissions Intensity of Modeled Beef Cow-Calf Grazing Systems in Southern Australia.

Simple SummaryLivestock production systems and the agricultural industries in general face challenges to meet the global demand for food, whilst also minimizing their environmental impact through the production of greenhouse gas (GHG) emissions. Livestock grazing systems in southern Australia are low input and reliant on pasture as a low-cost source of feed. The balance between productivity and GHG emission intensity of beef cow-calf grazing systems was studied at sites chosen to represent a range of climatic zones, soil and pasture types. While the climatic and edaphic characteristics of a location may impact on the emissions from a grazing system, management to efficiently use pasture can reduce emissions per unit product.A biophysical whole farm system model was used to simulate the interaction between the historical climate, soil and pasture type at sites in southern Australia and assess the balance between productivity and greenhouse gas emissions (expressed in carbon dioxide equivalents, CO2-eq.) intensity of beef cow-calf grazing systems. Four sites were chosen to represent a range of climatic zones, soil and pasture types. Poorer feed quality and supply limited the annual carrying capacity of the kikuyu pasture compared to phalaris pastures, with an average long-term carrying capacity across sites estimated to be 0.6 to 0.9 cows/ha. A relative reduction in level of feed intake to productivity of calf live weight/ha at weaning by feeding supplementary feed reduced the average CO2-eq. emissions/kg calf live weight at weaning of cows on the kikuyu pasture (18.4 and 18.9 kg/kg with and without supplementation, respectively), whereas at the other sites studied an increase in intake level to productivity and emission intensity was seen (between 10.4 to 12.5 kg/kg without and with supplementary feed, respectively). Enteric fermentationand nitrous oxide emissions from denitrification were the main sources of annual variability in emissions intensity, particularly at the lower rainfall sites. Emissions per unit product of low input systems can be minimized by efficient utilization of pasture to maximize the annual turnoff of weaned calves and diluting resource input per unit product.

Effects of dietary rapeseed meal on growth performance, digestion and protein metabolism in relation to gene expression of juvenile cobia (Rachycentron canadum)

A 60-day feeding trial in seawater floating cages (1.5×1.5×2.5m) was conducted to investigate the effects of dietary rapeseed meal (RM) levels on feed intake, growth, survival, digestion and protein metabolism in relation to gene expression of juvenile cobia (initial body weight 94.6g). Five isonitrogenous (crude protein 450gkg−1 of dry matter) and isoenergetic (20kJg−1) practical diets were formulated by replacing 0 (the control), 125, 250, 375 and 500gkg−1 fish meal protein with RM protein. Each diet was randomly fed to triplicate groups of fish, and each cage was stocked with 20 fish. Fish were fed twice daily (06:00 and 18:00) to apparent satiation. The survival ranged from 96.7 to 98.3%, and no significant difference was observed among dietary treatments (P>0.05). With increasing dietary RM levels, feed intake (FI), specific growth rate (SGR) and feed efficiency (FE) decreased. Fish fed the diet with 250gkg−1 or more protein from RM had significantly lower SGR and FE than the control group (P<0.05), but there was no significant difference in FI at this level compared with the control group (P>0.05). Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein and energy significantly decreased with increasing dietary RM levels (P<0.05). Fish fed the diet with 250gkg−1 or more protein from RM had significantly lower ADC values of crude protein and energy compared with the control group (P<0.05). Whole-body crude protein and crude lipid decreased with increasing dietary RM levels. Fish fed the diet with 500gkg−1 protein from RM had significantly lower whole-body crude protein and crude lipid compared with the control group (P<0.05). However, whole-body moisture and ash showed opposite trends with crude protein and crude lipid. Moisture, crude protein and crude lipid contents in cobia muscle showed similar trends with those in whole body. There were no significant differences in plasma ammonia, urea, cholesterol and amino acids among fish fed the experimental diets (P>0.05). Fish fed the diet with 500gkg−1 protein from RM had significantly lower aspartate aminotransferase (AST) activity in liver than the control group (P<0.05). Hepatic insulin-like growth factor I (IGF-I) gene expression level was significantly decreased in fish fed the diet with 500gkg−1 protein from RM compared with the control group (P<0.05). However, IGF-I gene expression level in dorsal muscle was significantly increased in fish fed this diet compared with the control group (P<0.05). No significant differences were observed in target of rapamycin (TOR) expression levels in cobia liver and dorsal muscle at different RM levels (P>0.05). Results of the present study indicated that protein from RM could substitute 125gkg−1 fish meal protein without influencing the growth, feed utilization and protein metabolism in cobia. The higher substitution levels of RM induced negative influences on feed intake, growth and hepatic IGF-I expression level.

The relationship between microbial N synthesis and urinary excretion of purine derivatives in Dorper × thin-tailed Han crossbred sheep

This study aimed to investigate the relationship between microbial N (MN) yield and urinary excretion of purine derivatives (PD) from the rumen in Dorper×thin-tailed Han crossbred sheep. Twelve Dorper×thin-tailed Han crossbred, non-castrated male lambs (41.3±2.8kg body weight) fitted with ruminal and duodenal cannulae were randomly assigned to one of three levels of DM intake: ad libitum intake, 70%, or 50% of the ad libitum intake, with four lambs at each level. The MN yield from the rumen was measured using 15N or purine bases (PB) as a microbial marker, and urinary PD were determined by colorimetric methods. Microbial components (OM, N, PB and ratio of PB to N) were not affected (P>0.05) by dietary treatment. The MN yield measured using PB was slightly lesser and more variable than using 15N. No difference in MN yield was found between markers. The efficiency of MN synthesis (g N/kg organic matter apparently digested in the rumen) was not affected (P>0.05) by feed intake regardless of the marker used. Urinary PD decreased significantly (P<0.05) with decreasing level of feed intake and the molar recovery of duodenal PB measured with digesta markers as urinary PD was 0.83 (r2=0.89, P<0.001). Urinary PD excretion was linearly correlated with DOMI (r2=0.94, P<0.001), and MN yield estimated by using either 15N or PB (r2=0.91 and 0.80, respectively, P<0.001). These results suggest that urinary PD excretion is an accurate indicator of MN synthesized in the rumen, and an equation, MN (g/d)=0.030+0.741×PD (mmol/d), is proposed to predict the MN yield from the rumen of Chinese sheep.

Energy requirements for maintenance and growth of Dorper crossbred ram lambs

This study aimed to determine the energy requirements of Dorper crossbred sheep that have been used for meat production in China. Thirty-five 1/2 Dorper×1/2 thin-tailed Han crossbred noncastrated ram lambs [34.1±0.6kg body weight (BW)] were used in a comparative slaughter trial. Seven ram lambs were randomly selected as the baseline group and slaughtered at 35kg BW. The remaining 28 lambs were randomly divided into four groups of seven lambs each. Three of the four groups were fed a mixed diet either for ad libitum intake, 60% or 45% of the ad libitum intake. The three groups were slaughtered when the ram lambs that were fed ad libitum reached 50kg BW. The ram lambs from the fourth group were also fed ad libitum as an intermediate group and slaughtered at 43kg BW. Total body energy, nitrogen, fat, ash, and moisture content were measured. In a digestibility trial, another 15 ram lambs (41.3±0.8kg BW) were housed in metabolism cages to estimate the metabolizable energy (ME) value of the diet at the three levels of feed intake. The daily net energy (NE) requirement for maintenance was 263kJ/kg0.75 of BW or 278kJ/kg0.75 of shrunk BW (SBW), with a partial efficiency of ME utilization for maintenance of 0.69. The NE requirement for growth ranged from 1.12 to 5.31MJ/d for daily gains of 100–400g BW, or from 1.29 to 6.18MJ/d for daily gains of 100–400g SBW. The partial efficiency of ME utilization for growth was 0.46. The energy requirements of Dorper×thin-tailed Han crossbred ram lambs were lower than those recommended by the British or American nutritional systems.

Feed intake and activity level of two broiler genotypes foraging different types of vegetation in the finishing period

A study was performed with 2 broiler genotypes (slow and medium growth) restricted in supplementary feed and foraging 2 different mixed vegetations (grass/clover or chicory) to identify possible benefits of herbage on nutrition during the finishing period (80 to 113 d of age). Three hundred birds were included in a 2 × 2 factorial design with groups of 25 birds replicated 3 times. The use of outdoor areas, performance, and forage intake were investigated. To identify possible differences in foraging activity, the use of the range was monitored one day per week at 4 different times of the day. Feed intake from foraging was estimated by killing 4 birds per plot (2 males and 2 females) in the morning and in the evening on 3 d during the experiment and measuring crop content. Vegetation type did not influence broiler use of the free-range area, feed intake, or performance. Differences in the use of the range area, activity level, and feed content in the crops were observed in relation to genotype, sex, age of broilers, and also the time of day. Foraging activity was positively correlated with age. Medium-growth broilers spent more time inside and closer to the broiler houses during the day with increased foraging activity during evenings, in contrast to the slow-growing broilers that showed a more uniform activity during the day. Based on the measurement of crop content it was estimated that the slow-growing genotype had a daily intake of 5 to 8 g of forage per day, whereas the medium-growing genotype had an intake of 9 g for females and 20 g for males. In conclusion, limitation of supplemented protein feed in the finishing period may be acceptable for broilers that have access to highly nutritious vegetation.

Are there benefits in introducing dairy heifers to the main dairy herd in the evening rather than the morning?

Twenty-eight Holstein Friesian dairy heifers were assigned to 1 of 2 treatments after calving. These experimental heifers were introduced to an established group of resident cows either between 0600 and 0800h (i.e., after morning milking, a.m.) or between 1600 and 1800h (i.e., after evening milking, p.m.). The size of the resident group remained constant at 18 animals (12 multiparous cows and 6 primiparous cows). There were 5 replicate or resident groups in total, and 2 to 3 nonexperimental primiparous cows in each group were replaced by a.m. and by p.m. heifers as they calved. Fresh total mixed ration was provided daily between 1000 and 1030h, and concentrate feed was offered in the milking parlor. The behavior of the experimental heifers was assessed over a 2-h period immediately after mixing into the resident group, and also after feed provision during the first month in the group. In addition, time spent lying was assessed each week for 1 mo using data loggers attached over 24-h periods. The lying behavior and location of the entire group was also assessed by direct observations during the 2-h period before evening milking on 2 consecutive days each week for 1 mo. The time spent feeding by experimental heifers was recorded automatically using computerized feeding gates. Milk production, milk cortisol concentrations, and changes in body condition and body weight were also assessed over the first month after calving. Heifers in the a.m. treatment spent longer in receipt of aggressive behaviors such as threats, butts, and chases immediately after mixing compared with those in the p.m. treatment. During the feeding periods, heifers in the a.m. treatment were observed feeding for longer, showed less pen exploration, and also received more butts. No significant treatment effects were shown on overall feed intake levels, milk yield, milk cortisol concentrations, body weight, or body condition score loss. However, feed intakes were higher in the a.m. treatment during the second week after mixing, and automated recordings showed that a.m. animals spent longer average periods of time feeding. No significant treatment differences were shown in overall time spent lying, with heifers in both treatments lying for less than 4h during the first 24h in the group. Observations of the entire group showed that p.m. heifers spent less time lying than resident animals or a.m. heifers. In conclusion, the reduction in received aggression and the lack of adverse effects on performance (milk production and weight and condition loss) suggest that heifers should be introduced to the main dairy herd after evening rather than morning milking. Further research to determine the relative importance of time of day and time since feeding on behavior immediately after mixing would be beneficial.

Response analysis of the Iberian pig growing from birth to 150 kg body weight to changes in protein and energy supply1

A total of 251 growing-finishing Iberian (IB) pigs, 32 of which were suckling piglets, were used in 5 separate sets of trials. The comparative slaughter procedure was used to determine nutrient and energy retention at several stages of growth from birth to 150 kg BW. A factorial arrangement was used within each set of trials, involving several concentrations of ideal protein in the diets as 1 factor and 2 or 3 levels of feed intake as the other. The main objective of these studies was to derive the optimal protein-to-energy ratio in the diet to allow for the expression of maximum protein deposition rates. The effect of feed restriction on growth performance, protein deposition, and fat deposition was also assessed. According to allometric equations, empty BW (EBW) was related to whole body components or total chemical constituents of empty body mass (P < 0.001). For pigs receiving solid feed, highly statistically significant multiple regression equations were constructed, which derived nutrient (g/kg) or energy (MJ/kg) composition as a function of EBW, dietary protein-to-energy ratio, and level of feeding (P < 0.001). In pigs offered adequate protein-to-energy diets, ADG at each stage of production was predicted as a function of the average BW and feeding level (P < 0.001). It was observed that the estimates of ME required for maintenance and net efficiency of utilization of ME for growth change were within rather narrow ranges throughout the growth stages studied. Preferred values (413 kJ/kg BW(0.75) × d(-1) and 0.593 for ME(m) and k(g), respectively) were obtained by regressing total energy retention (kJ/kg BW(0.75) × d(-1)) against ME intake (kJ/kg BW(0.75) × d(-1)). A multiple-regression approach revealed that in the IB pig, ME costs for protein deposition and fat deposition reach 60 and 62 kJ/g, which is considerably greater than in conventional or lean pig genotypes. In the IB pig, the maximum daily rate of protein deposition (PD(max), g) seemed to follow a linear-plateau shape with a breaking point at 32.5 kg BW, beyond which PD(max) remained at an average rate of 75 g × d(-1). The marginal efficiency of body protein deposition was estimated at each growth stage. In pigs fed on optimal or suboptimal protein-to-energy diets, the relationship between PD and ME intake declined, following a curvilinear pattern with increasing BW; thus, implying relative increases in lipid gain as BW increased.

Modelling urinary purine derivatives excretion as a tool to estimate microbial rumen outflow in alpacas (Vicugna pacos)

Three experiments were carried out to establish a model to estimate the forestomach microbial yield based on the urinary excretion of purine derivatives (PD: allantoin, uric acid, xanthine and hypoxantine) in alpacas (Vicugna pacos). In Experiment 1, endogenous PD excretion was measured in two fasted adult male alpacas for seven consecutive days. Daily urinary PD excretion (μmol/kg BW0.75) decreased during fasting to a minimum value of 194.8 (s.e. 18.4), ranging from 215.3 to 174.3. In Experiment 2, the relationship between purine bases (PB) input and urinary PD output was defined in two alpacas fitted with an infusion catheter at the terminal third compartment of the forestomach (C3). Animals were fed alfalfa hay at a maintenance level, and four RNA-doses (4.2, 8.3, 12.5 and 16.6mmol PB/day; RNA from Torula yeast) were continuously infused at random into the C3 in four successive 120 h-periods. Urinary recovery of C3 infused purines averaged 0.615 (s.e. 0.0006)mmol/day. In Experiment 3, urinary PD response to levels of feed intake corresponding to 100, 75, 50 and 20% of the previous voluntary intake was evaluated. The amount of PD excretion in urine increased linearly (r=0.867) with digestible organic matter intake (DOMI), and the slope of the regression (16.7mmol PD/kg DOMI) can be assumed as an index of microbial yield.

Small intestine development in chicks after hatch and in pigs around the time of weaning and its relation with nutrition: A review

The period after hatch in broilers and around the time of weaning in pigs is critical for development and for adaptation of the small intestine to the nutritional changes. In broilers, the small-intestinal weight relative to body weight and villous height increase rapidly during the first week after hatch. After the first week, the relative small-intestinal weight decreases gradually, but the villous height continues to increase. In pigs, at 4 d after weaning, villous height decreases to about 60% of the pre-weaning height when weaned between 1 and 4 wk of age. Two weeks after weaning, this recovers to similar values as in unweaned control animals independent of weaning age. Small-intestinal development after hatch and after weaning consistently deteriorates at low feed intake levels and with suboptimal protein nutrition. These findings stress the importance of applying an optimal nutritional strategy in these phases of life to reach optimal small-intestinal development.

Effects of feeding level and sexual maturation on carcass and fillet characteristics and indices of protein degradation in rainbow trout (Oncorhynchus mykiss)

Sexual maturation in salmonids requires mobilization of proteins from muscle tissue, which is evidenced by increased expression of proteolysis-related genes and decreased muscle protein content. However, it is unknown how ration level affects this proteolytic response. In the current study, female diploid rainbow trout (Oncorhynchus mykiss) approaching ovulation were fed for 12weeks at 0.25% and 0.50% tank biomass, and to apparent satiation. Triploid trout, which exhibit little ovarian growth, were included at the 0.50% ration level. Gonad somatic index increased in diploids from 3.98% to approximately 13% and was unaffected by ration. Reduced feed intake and maturation negatively affected protein and lipid deposition in skeletal muscle, as indicated by reduced fillet weight and reduced fillet protein and lipid content. During mid-vitellogenesis, expression of genes involved in proteolytic pathways was higher in diploids compared to triploids and the majority of the differentially expressed transcripts were cathepsin and autophagy-related genes. These differences increased with maturation and expanded to include multiple components of the proteasome, ubiquitin ligases, calpastatins, and caspase 9. Expression patterns of multiple proteolysis-related genes suggest that fish consuming the moderate 0.50% ration had the lowest capacity for protein degradation. In summary, these results suggest that maturation increases protein degradation and that higher levels of feed intake are unable to alleviate these effects. However, higher levels of feed intake prevent a net loss of muscle protein, suggesting that dietary nutrients are able to replace endogenous nutrients mobilized from skeletal muscle in support of gonad growth.

Effect of feed intake level on ileal digestibilities of crude protein and amino acids in diets for piglets

The study was conducted to determine the effect of graded levels of feed intake on apparent (AID) and standardized (SID) ileal digestibilities of crude protein (CP) and amino acids (AA) in diets for piglets. The piglets were surgically fitted with simple T-cannulas at the distal ileum. The cornstarch-casein-soybean meal-based diets were fed at three graded levels of feed intake corresponding to 30, 45 and 60 g kg(-1) body weight (BW) per day. The AID and SID of most AA were quadratically affected by the feed intake level (P≤0.05). Initially, both AID and SID of most AA increased up to 1.9 percentage units as the feed intake level was increased from 30 to 45 g kg(-1) BW. Thereafter, these AID and SID values decreased by 2.6 and 2.7 percentage units, respectively, as the feed intake level was further increased from 45 to 60 g kg(-1) BW. Because the voluntary feed intake is highly variable in piglets after weaning, comparison of ileal AA digestibilities between and within studies may be confounded by variations in feed intake level. Thus, when designing digestibility studies with piglets, a standardization of feed intake should be taken into consideration.

Sheep fed only silage or silage supplemented with concentrates. 1. Effects on ewe performance and blood metabolites

In Scandinavia, winter diets for sheep are forage-based, with concentrates commonly being added in the latter part of pregnancy and during lactation. In organic production, however, the level of concentrates is restricted and rations are sometimes purely forage-based. It is uncertain if feeding only forage fulfils the nutritional requirements of high producing ewes. The aim of this project was to compare the performance and nutrient status of ewes fed only silage from mid-pregnancy until the end of lactation (SIL), or silage and a maximum of 40% concentrates before lambing, and 50% afterwards (CON). The study was conducted during two consecutive indoor feeding seasons (Y1 and Y2), with 41 and 51 ewes, respectively. In Y1, the silage was of high nutrient quality, whereas the silage used in Y2 had a lower content of energy and protein and more fibres. The general level of feed intake was lower in Y2 than Y1. There were significant differences in body condition between SIL and CON ewes in both years. Blood samples from the ewes were analyzed for betahydroxybutyrate (BHB), non-esterified fatty acids (NEFA) and urea. In both years, SIL ewes had higher NEFA and BHB than CON ewes two weeks after lambing, In Y2, urea was lower in SIL ewes than in CON ewes after lambing. Litter size also had a significant impact on the blood metabolites. In conclusion, feeding only silage is not recommended for ewes with more than one lamb, unless the silage is of a very high nutritional quality.

Effect of different levels of short-term feed intake on folliculogenesis and follicular fluid and plasma concentrations of lactate dehydrogenase, glucose, and hormones in Hu sheep during the luteal phase

This study investigated the effects of short-term food restriction or supplementation on folliculogenesis and plasma and intrafollicular metabolite and hormone concentrations. Ewes were randomly assigned to three groups: the control group received a maintenance diet (M) while the supplemented group and restricted group received 1.5×M and 0.5×M respectively on days 6-12 of their estrous cycle. Estrus was synchronized by intravaginal progestogen sponges for 12 days. On days 7-12, blood samples were taken. After slaughter, the ovarian follicles were classified and the follicular fluid was collected. Compared with restriction, supplementation shortened the estrous cycle length, decreased the number of follicles 2.5-3.5 mm and follicular fluid estradiol (E2) concentration, increased the number of follicles>3.5 mm and plasma glucose, insulin and glucagon concentrations, and augmented the volume of follicles>2.5 mm. Restricted ewes had higher intrafollicular insulin concentration, but it was similar to that of supplemented ewes. Compared with follicles≤2.5 mm, the intrafollicular glucose and E2 concentrations were increased and the testosterone, insulin, and glucagon concentrations and lactate dehydrogenase (LDH) activity were decreased in follicles>2.5 mm. Only in restricted ewes were intrafollicular LDH and testosterone concentrations in follicles≤2.5 mm not different from those in follicles≤2.5 mm. In conclusion, the mechanism by which short-term dietary restriction inhibits folliculogenesis may involve responses to intrafollicular increased E2, testosterone, and LDH levels in late-stage follicles. This may not be due to the variation of intrafollicular insulin level but rather due to decreased circulating levels of glucose, insulin, and glucagon.

English

Alterations in antioxidant enzymes and lipid peroxidation was studied in 90 Wistar albino rats exposed to cycads and fed with Nigerian-like and western-like diets supplemented with folic acid. The animals were divided into three diet classes of 30 animals each. One group was fed with a wholly compounded Nigerian-like diet (NLD) which was low in protein and high in carbohydrate and fiber. Another group was fed with a western like diet (WLD) which was high in protein and fat, while the third group of animals was fed with a normal diet which served as the control class. The animals of each class were further divided into three subgroups of ten rats each. In each subclass, one group received the diet alone; another group received the diet and cycads, while the third group received the diet and folic acid. Low levels of catalase, feed intake and faecal output was observed with experimental animals fed NLD as compared to WLD and normal diet (ND) fed animals. High levels of antioxidant enzymes: super oxide dismutase, catalase and glutathione reductase as well as low levels of lipid peroxidation was observed with the addition of folic acid to the diets of experimental rats. These results suggest the role of folic acid in diet and colon carcinogenesis. Key words: Antioxidant enzymes, cycads, diets, folic acid, lipid peroxidation.

Proteolytic response to feeding level in rainbow trout ( Oncorhynchus mykiss)

In fish, a quadratic relationship between feed intake and feed efficiency is observed most-often, with optimal nutrient retention occurring at moderate levels of feed restriction. Determining how mechanisms controlling nutrient utilization are affected by feed intake, with a particular emphasis on those that impact protein turnover, will enable a better understanding of the metabolic processes that contribute to variations in nutrient retention. In the present study, rainbow trout were fed for 10 weeks at different levels of satiation and indices of growth, nutrient retention, and protein degradation were determined. As-fed and dry-weight feed efficiency, specific growth rate, and protein, lipid, and energy retention displayed a positive quadratic response to feeding level (P < 0.05), with optimal feed efficiency calculated to occur at 76% of satiation. Concentrations of plasma free amino acids increased linearly (P < 0.001) and plasma concentrations of insulin-like growth factor-I (IGF-I) displayed a positive quadratic response across feeding level (P < 0.01). The myofibrillar protein degradation product, 3-methylhistidine (3-MH), displayed a negative quadratic response (P < 0.02) to feed intake. These data suggest that an increase in protein degradation occurs during high levels of feed intake that is partially driven by changes in plasma IGF-I, which displayed a slight decrease in plasma concentration approaching satiation and may contribute to the associated reductions in protein retention and feed efficiency. Proteolytic genes that also displayed quadratic responses included the ubiquitin ligase, fbxo32 (P < 0.01), and a cathepsin, ctsd (P < 0.01), indicating an increase in the capacity to degrade proteins at high levels of feed intake. Therefore, interrupting the up-regulation of the ubiquitin–proteasome and lysosomal systems during high levels of feed intake may impede increases in protein degradation, reduce rates of protein turnover and subsequently improve protein retention and feed efficiency.

Effects of dietary cholesterol on growth performance, feed intake and cholesterol metabolism in juvenile turbot ( Scophthalmus maximus L.) fed high plant protein diets

A 9-week growth trial was conducted to investigate the effects of dietary cholesterol supplementation on growth performance, feed intake and cholesterol metabolism of juvenile turbot ( Scophthalmus maximus L.) fed high plant protein diets. A fish meal diet (diet FM) with 58% FM was formulated, and this diet was used as control. The other four diets were formulated to contain 14.5% FM, 42.0% soybean meal (SBM), and 18.5% wheat gluten meal. The four diets were supplemented with 0.0%, 0.5%, 1.0% and 1.5% cholesterol, respectively, and were isonitrogenous and isolipidic to the diet FM. They were named as diet C-0.0%, C-0.5%, C-1.0% and C-1.5%, respectively. The final dietary cholesterol concentrations were 0.30%, 0.77%, 1.25%, and 1.78%, respectively. That in control diet was 0.63%. The results showed that weight gain rate (WGR) and feed efficiency rate in fish fed diet FM were significantly higher than those in fish fed other diets ( P < 0.05). Furthermore, compared with fish fed diet C-0.0%, fish fed diet C-1.0% significantly enhanced WGR, feed intake (FI) and cholesterol levels in plasma and liver. However, WGR and FI in fish fed diet C-1.5% were significantly lower than those in fish fed diet C-1.0% ( P < 0.05). Fish fed diet C-1.0% showed significantly higher whole-body lipid content than that of fish fed other diets ( P < 0.05). The total cholesterol (TC), free cholesterol (FC), cholesterol esters, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) contents in fish plasma, TC and cholesterol esters in fish liver, and TC in fish feces were significantly correlated with dietary cholesterol contents, and correlated coefficients were above 0.74. Fish fed diet C-0.0% showed the lowest fecal total bile acid and activity of cholesterol 7α hydroxylase among dietary treatments. These results suggested that 1.25% of dietary cholesterol is helpful for juvenile turbot fed high plant protein diets to get significantly better growth rate without negative effects.

Effects of dietary protein sources on feed intake, growth and plasma thyroid hormones levels of Japanese flounder (Paralichthys olivaceus)

An 8-week feeding trial was conducted to compare the effects of dietary protein sources on growth performance and plasma thyroid hormones levels of Japanese flounder Paralichthys olivaceus. Four isonitrogenous and isoenergetic diets were formulated to contain one of the followings as main protein source: fish meal (FM), fish protein concentrate (FPC), soy protein concentrate (SPC), and soy protein isolate (SPI). Each diet was randomly assigned to triplicate aquaria stocked with 25 fish each. The feed intake, specific growth rate, feed efficiency, and protein efficiency ratio in fish fed fish protein-based diets were significantly higher than those in fish fed soy protein-based diets. Feed intake and specific growth rate were significantly higher in FM treatment compared to FPC treatment and higher in SPI treatment compared to SPC treatment. The FM treatment had significantly higher levels of plasma cortisol, triiodothyronine, and thyroxin than the other treatments. These results indicate that high inclusion levels of soy protein in diets markedly inhibit the feeding rate and growth of P. olivaceus due to poor palatability caused by the removal of feeding stimulants and/or the incorporation of feeding deterrents. The reduced growth may be partly attributed to the amino acid imbalance, absence of small nitrogen compounds, and presence of antinutritional factors.