Level Of Feed Intake Research Articles

Effect of feed intake level and dietary protein content on the body temperature of pigs housed under thermo neutral conditions.

Feed intake and diet composition appear to affect the body temperature of pigs. Two trials were conducted to analyse the effect of feed intake level and dietary protein content on the intestinal temperature (IT) of pigs housed under thermo neutral conditions. Ten pigs (64.1±1.3kg initial body weight) fitted with an ileal cannula were used. A thermometer set to register the IT at 5-min intervals was implanted into the ileum through the cannula. In both trials, the ambient temperature ranged from 19.1 to 21.6°C and the pigs were fed at 07:00 and 19:00hr (same amount each time). In trial 1, the pigs were fed daily 1.2 or 1.8kg of a wheat-soybean meal diet. The IT followed a similar pattern along a 24-hr period regardless the feed intake level. The IT rapidly increased up to 0.61 and 0.74°C after the morning meal and up to 0.53 and 0.47°C after the evening meal in pigs fed 1.2 and 1.8kg/d respectively. The postprandial IT was higher in pigs fed 1.8kg after each meal (p<.05). In trial 2, pigs were fed daily 1.8kg of a low (11%) or a high (22%) crude protein diet. The IT followed a similar pattern along the 24-hr period regardless the dietary protein level. The postprandial IT did not differ between pigs fed the low protein or the high protein (p>.10). The IT rapidly increased up to 0.66 and 0.62°C after the morning meal in pigs fed the high- and low-protein diet (p<.05), but there was no change after the evening meal (p>.10). In conclusion, the feed intake level affected the IT of pigs housed under TN conditions, but the dietary protein content had no effect.

Effect of growth hormone overexpression on gastric evacuation rate in coho salmon.

Growth hormone (GH) transgenic (T) coho salmon consistently show remarkably enhanced growth associated with increased appetite and food consumption compared to non-transgenic wild-type (NT) coho salmon. To improve understanding of the mechanism by which GH overexpression mediates food intake and digestion in T fish, feed intake and gastric evacuation rate (over 7days) were measured in size-matched T and NT coho salmon. T fish displayed greatly enhanced feed intake levels (~2.5-fold), and more than 3-fold increase in gastric evacuation rates relative to NT coho salmon. Despite the differences in feed intake, no differences were noted in the time taken from first ingestion of food to stomach evacuation between genotypes. These results indicate that enhanced feed intake is coupled with an overall increased processing rate to enhance energy intake by T fish. To further investigate the molecular basis of these responses, we examined the messenger RNA (mRNA) levels of several genes in appetite- and gastric-regulation pathways (Agrp1, Bbs, Cart, Cck, Glp, Ghrelin, Grp, Leptin, Mc4r, Npy, and Pomc) by qPCR analyses in the brain (hypothalamus, preoptic area) and pituitary, and in peripheral tissues associated with digestion (liver, stomach, intestine, and adipose tissue). Significant increases in mRNA levels were found for Agrp1 in the preoptic area (POA) of the brain, and Grp and Pomc in pituitary for T coho salmon relative to NT. Mch and Npy showed significantly lower mRNA levels than NT fish in all brain tissues examined across all time-points after feeding. Mc4r and Cart for T showed significantly lower mRNA levels than NT in the POA and hypothalamus, respectively. In the case of peripheral tissues, T fish had lower mRNA levels of Glp and Leptin than NT fish in the intestine and adipose tissue, respectively. Grp, Cck, Bbs, Glp, and Leptin in stomach, adipose tissue, and/or intestine showed significant differences across the time-points after feeding, but Ghrelin showed no significant difference between T and NT fish in all tested tissues.

Effects of grass silage quality and level of feed intake on enteric methane production in lactating dairy cows.

The objective of this study was to determine the effect of level of feed intake and quality of ryegrass silage as well as their interaction on enteric methane (CH) emission from dairy cows. In a randomized block design, 56 lactating dairy cows received a diet of grass silage, corn silage, and a compound feed meal (70:10:20 on DM basis). Treatments consisted of 4 grass silage qualities prepared from grass harvested from leafy through late heading stage, and offered to dairy cows at 96 ± 2.4 (mean ± SEM) days in milk (namely, high intake) and 217 ± 2.4 d in milk (namely, low intake). Grass silage CP content varied between 124 and 286 g/kg of DM, and NDF content between 365 and 546 g/kg of DM. After 12 d of adaptation, enteric CH production of cows was measured in open-circuit climate-controlled respiration chambers for 5 d. No interaction between DMI and grass quality on CH emission, or on milk production, diet digestibility, and energy, and N retention was found ( ≥ 0.17). Cows had a greater DMI (16.6 vs. 15.5 kg/d; SEM 0.46) and greater fat- and protein-corrected milk (FPCM) yield (29.9 vs. 25.4 kg/d; SEM 1.24) at high than low intake (both ≤ 0.001). Apparent total-tract nutrient digestibility was not affected ( ≥ 0.08) by DMI level. Total enteric CH production (346 ± 10.9 g/d) was not affected ( = 0.15) by DMI level. A small, significant ( = 0.025) decrease at high compared with low intake occurred for CH yield (21.8 ± 0.59 g/kg of DMI; -4%). Methane emission intensity (12.8 ± 0.56 g/kg of FPCM; -12%) was considerably smaller ( ≤ 0.001) at high intake as a result of greater milk yields realized in early lactation. As grass quality decreased from leafy through late heading stage, FPCM yield and apparent total-tract OM digestibility declined (-12%; ≤ 0.015), whereas total CH production (+13%), CH yield (+21%), and CH emission intensity (+28%) increased ( ≤ 0.001). Our results suggest that improving grass silage quality by cutting grass at an earlier stage considerably reduces enteric CH emissions from dairy cows, independent of DMI. In contrast, losses of N in manure increased for the earlier cut grass silage treatments. The small increase in DMI at high intake was associated with a small to moderate reduction in CH emission per unit of DMI and GE intake. This study confirmed that enteric CH emissions from dairy cows at distinct levels of feed intake depend on the nutritive value and chemical composition of the grass silage.

Gestating sows have greater digestibility of energy in full fat rice bran and defatted rice bran than growing gilts regardless of level of feed intake.

The first objective of this experiment was to test the hypothesis that apparent total tract digestibility (ATTD) of GE and nutrients in full fat rice bran (FFRB) and defatted rice bran (DFRB) determined in gestating sows is greater if feed is provided at 1.5 × the ME required for maintenance than at 3.5 × the ME requirement. The second objective was to test the hypothesis that the ATTD of GE and nutrients and the concentrations of DE and ME in FFRB and DFRB is not different between growing gilts and gestating sows if both groups of animals are fed 3.5 × the maintenance requirement for ME. Forty eight gestating sows (parity 2 to 6) were allotted to 3 diets and 2 levels of feed intake (i.e., 1.5 or 3.5 × the maintenance requirement for ME) in a randomized complete block design, with 4 blocks of 12 sows and 2 replicate sows per block for a total of 8 replicate sows per diet. Twenty four growing gilts (51.53 ± 3.1 kg BW) were randomly allotted to the same 3 diets, but all gilts were fed at 3.5 × the maintenance requirement for ME. A basal diet containing corn and soybean meal and 2 diets that consisted of 60% basal diet and 40% FFRB or DFRB were used. Results of the experiment indicated that there were no effects of level of feed intake of sows on ATTD of GE, DM, OM, or NDF, or on concentrations of DE and ME. However, concentrations of DE and ME were greater ( < 0.05) in FFRB than in DFRB regardless of feed intake level. The ATTD of GE, OM, DM, and NDF of diets containing FFRB or DFRB was less ( < 0.05) than in the basal diet, regardless of the physiological stage of the animals. However, the ATTD of GE, OM, and NDF of the basal diet and diets containing FFRB or DRFB was greater ( < 0.05) in gestating sows than in growing gilts. Concentrations of DE and ME in the diets were also greater ( < 0.05) if determined in gestating sows than in growing gilts. The ATTD of GE and the concentrations of DE and ME of FFRB were greater ( < 0.05) than in DFRB and these values were also greater ( < 0.05) in gestating sows than in growing gilts. In conclusion, the level of feed intake by gestating sows did not affect the digestibility of GE and nutrients or the concentrations of DE and ME in diets or in FFRB or DFRB, but the ATTD of GE and the concentration of DE and ME in diets and in FFRB and DFRB were greater in gestating sows than in growing gilts.

Physiological adaptations of ruminants and their potential relevance for production systems

ABSTRACT Herbivores face the dilemma that the level of feed intake is negatively related to factors that determine digestive efficiency, such as thoroughness of ingesta comminution by chewing, and retention of digesta in the digestive tract. Ruminants have evolved particular adaptations to solve this dilemma. Most ruminants share the characteristic of “digesta washing”: fluid moves through their digestive tract faster than particles, thus effectively washing very fine particles, such as bacteria, out of the digesta plug. As the forestomach is followed by auto-enzymatic digestion, this allows a continuous, increased harvest of microbes from the forestomach. True rumination only evolved twice, in the camelids and the true ruminants. These both evolved a density-dependent sorting mechanism based on physical separation of the digesta by the process of flotation and sedimentation, ensuring that the process of rumination is applied to large particles. Differences in this sorting mechanism might facilitate a faster digesta processing in true ruminants as compared with camelids. The hallmark of ruminant digestive anatomy is the omasum, in which the fluid required for both digesta washing and the reticular separation mechanism is re-absorbed. In ruminants of the tribe Bovini, the omasum has reached the largest size and this group has a particularly great forestomach fluid throughput. Increasing the degree of digesta washing even more should increase microbial harvest from the forestomach and reduce the susceptibility to acidosis. At the same time, it should result in a metabolic state of the microbiome more tuned towards biomass production and less towards methanogenesis. Enhancing the forestomach fluid throughput by selective breeding could represent a promising way to further advance the productivity of the ruminant digestive tract.

Changes in faecal bacteria during fattening in finishing swine

Body fat accumulation in mice and human is linked to the percentage of Firmicutes and Bacteroidetes, two bacterial phyla dominant in the large intestine. However, little is known about the relationship between the composition of the gut microbiota and fattening in pig. This study aimed to investigate the abundance of Firmicutes, Bacteroidetes, and Bacteroides, which is the major genus within Bacteroidetes, in porcine faeces during fattening. Ten 4-month-old crossbred pigs were given free access to commercial feed for fattening and water for 14 weeks. Daily feed intake and body weight were measured every 2 weeks. Faecal samples were collected at 0, 4, 8, and 14 weeks, and plasma samples were collected every 2 weeks. Daily feed intake increased until 8 weeks, and then decreased. Body weight increased with fattening during the experimental period. Feed efficiency showed high values at 0–4 and 6–8 weeks. The level of Firmicutes increased (P < 0.05), whereas those of Bacteroides and Bacteroidetes decreased (P < 0.05) with fattening. The total short chain fatty acid content in the faeces increased (P < 0.05) with fattening until 8 weeks and then decreased (P < 0.05) at 14 weeks. There were no significant relationships between the level of Firmicutes and feed intake or plasma leptin concentration. The levels of Bacteroidetes and Bacteroides correlated with feed intake, body weight, and plasma leptin or plasma urea nitrogen (PUN) concentration. Our results suggested that the level of Firmicutes increased and those of Bacteroidetes and Bacteroides decreased with increase in feed intake and body weight, similar to previous results obtained for mice and human. However, energy extraction from feed was not influenced by compositional alteration of gut flora, because daily gain and feed efficiency did not show high values towards the end of the fattening period. Manipulating the gut microbiota might help improve fattening performance, although further studies are necessary to understand the relationships between the composition of gut microbiota and energy absorption.

The Effect of Level of Feed Intake on Digestibility, Nitrogen Balance and Microbial Protein Synthesis in Sheep

The Effect of Level of Feed Intake on Digestibility, Nitrogen Balance and Microbial Protein Synthesis in Sheep

The decline in digestive efficiency of US dairy cows from 1970 to 2014

Since the year 1970, US milk production per cow has more than doubled, in part because of large increases in feed intake. It is well established that increasing feed intake reduces diet digestibility in dairy cattle. Our objective was to determine whether the digestive efficiency of US dairy cows had also changed. We assembled a data set consisting of diet digestibility measured either by total collection of feces or by use of indigestible neutral detergent fiber (NDF) in lactating dairy cow studies published in the Journal of Dairy Science from July 1970 to July 2014. The data set contained 575 treatment means from 154 individual research trials conducted at 26 US institutions. Based on regression analysis, mean milk yield and dry matter intake (DMI) between 1970 and 2014 increased by 19.7 and 10.3 kg/d, respectively. Temporal effects on digestibility [dry matter (DM), crude protein (CP), and NDF] were determined using the regression model Yi = YEAR1970i + CPi + NDFi + ei, where YEAR1970i is the publication year minus 1970, CPi and NDFi are diet constituents (% of diet DM) that were included to account for their known effects on digestibility, and ei is the residual error. Dry matter digestibility decreased 0.07 percentage units/yr for a total reduction of 3.08 percentage units since 1970. Furthermore, CP and NDF digestibilities decreased 0.04 and 0.17 percentage units/yr, respectively. To account for the potential effect of feed intake on digestibility, DMI as a percentage of body weight was added to the regression model. With DMI as a percentage of body weight in the model, temporal changes in DM, CP, and NDF digestibilities were no longer significant. This suggested that the apparent decline in DM digestibility could be mostly accounted for by simultaneous increases in level of feed intake. Despite lower apparent digestive efficiency, the modern dairy cow has greater production efficiency than the 1970s dairy cow because she produces more milk per unit of feed consumed and digested.

Enteric Methane Conversion Factor for Dairy and Beef Cattle: Effects of Feed Digestibility and Intake Level

Abstract. The objectives of this study were to identify the sources of variations in reported methane (CH4) conversion factor (Ym) for dairy and beef cattle through a meta-analytical approach, and to specifically investigate the effects of feed digestibility and intake level on Ym, as well as the alternative expression of methane conversion factor on a digestible energy basis (Dm). Results from 89 peer-reviewed journal articles published from 1992 to 2015 were compiled, and data across studies were analyzed statistically using the MIXED procedures of SAS. For housed cattle, Ym increased significantly with forage-to-concentrate ratio of feed and was also affected by breed. For grazing cattle, Ym varied by geographic region. The observed effect of forage-to-concentrate ratio of feed for housed cattle and the effect of geographic region for grazing cattle on enteric CH4 emissions could both be related to the effect of feed digestibility. Dm was affected significantly by both energy intake level and energy digestibility of feed as well as their interaction. Higher energy digestibility of feed and higher energy intake level of cattle resulted in a lower percentage of digestible energy intake being converted to CH4. Results of this study improved estimation of CH4 conversion factor according to animal husbandry practices. Compared with the Ym approach, the use of CH4 conversion factor on a digestible energy basis can better represent the large variation among diets and the effects of different dietary emission mitigation strategies.

Occludin expression and regulation in small follicles of the layer and broiler breeder hen

Synchronized yolk accumulation and follicle development are essential for egg production in oviparous species. In birds, yolk is incorporated into the oocyte by an avian specific yolk receptor (LR8), and it has been suggested that occludin (OCLN), a tight junction protein, mediates transfer of yolk material to the oocyte surface. OCLN may be a key regulator of yolk accumulation and follicle growth, however, the expression and regulation of OCLN in granulosa cells during various stages of follicle development is unknown. In the first experiment, we found that LR8 and OCLN mRNA were highest in small follicles within the ovary. In addition, OCLN decreased with increasing follicle size. OCLN mRNA was more abundant in the germinal disc region of the granulosa cell layer than the non-germinal disc region. In addition, we found epidermal growth factor (EGF) and activin B, decreased OCLN mRNA, while activin A increased OCLN. In the second experiment, restricted fed (RF) broiler breeder hens were randomly divided into two groups and one group remained on RF and the other was fed ad libitum (FF). OCLN expression in granulosa cells of 3–5mm follicles of FF hens was lower compared to RF hens and yolk weights were higher in the FF group, however, LR8 mRNA in small whole follicles (<3mm) did not differ between groups. In conclusion, the level of feed intake is related to or may directly regulate OCLN mRNA expression or may have an indirect effect through paracrine or autocrine factors in the ovary.

Nutritional value of whole cereal meals for European sea bass (Dicentrarchus labrax) juveniles

The nutritional value of whole wheat, corn, rye and barley was evaluated for European sea bass. Four isoproteic and isolipidic diets containg 30% of each whole cereal meal were formulated. A growth trial and a digestibility trial were conducted and fish performance was evaluated in terms of growth, feed intake, feed utilization, macronutrients digestibility, liver composition, glycaemia and cholesterolemia levels and gut histomorphology.Growth and feed utilization ranged from 1.43 to 1.46 and from 0.55 to 0.58, respectively, and were similar among experimental groups. Whole body and liver composition, hepatosomatic and visceral indexes were also not affected by dietary composition. Corn diet revealed the lower dry matter (62.9) and starch (55.5) apparent digestibility coefficients. Protein digestibility in fish fed the rye diet was the lowest of all groups (91.3) and differed from that of wheat diet group (93.2), which might be due to antinutritional factors present in this feedstuff. Plasmatic glucose levels suggested a slower absorption rate in fish fed barley and corn diets. No signs of enteropathy related to the whole cereal meals were observed. Among cereals tested, rye seemed to be the less tolerated by sea bass, although all diets were well accepted and sea bass performed equally well with all diets.

Effects of grass silage quality and level of feed intake on enteric methane production in lactating dairy cows

Effects of grass silage quality and level of feed intake on enteric methane production in lactating dairy cows

SEMEN PHYSICAL CHARACTERISTICS, BLOOD PARAMETERS AND SOME PHYSIOLOGICAL ESTIMATES OF RABBIT BUCKS ADMINISTERED WITH BEE POLLEN UNDER UPPER EGYPT CLIMATIC CONDITIONS

The present study was conducted to evaluate the effect of orally administration of bee pollen (BP) levels at 500 and 1000mg/buck as capsules form on semen physical characteristics as well as some hematological and physiological traits of rabbit bucks exposed to high temperature under Upper Egypt climatic conditions. A total of 30 rabbit bucks (15 V-line & 15 Moshtohor); 52 weeks old, were equally classified into three experimental groups. Bucks in the 1st group (control) were fed on a commercial ration, while those in the 2nd and 3rd groups were fed on the basal diet and orally administered daily with 500 and 1000mg BP/buck, respectively during the experiment, which lasted 56 days. The obtained findings revealed that the means of white blood cells (WBCs), hemoglobin (Hg), Hematocrit (HCT), MCV (%), total protein (TP) of Moshtohor rabbit bucks were significantly increased, while the total feed intake (TFI) and glucose level were significantly decreased than those of the V-line rabbit bucks. The means of live sperm (%), mass motility (%), conc./ml (106), conc./ej (106) and testosterone (ng/ml)in Moshtohor bucks increased significantly (P<0.01) by about 4.3, 6.0, 24.0, 28.6 and 16.8%, while reaction time (RT) was significantlydecreased by about 20.2% than those of V-line bucks. The bucks treated with both of 500 and 1000mg BP /rabbit had significantly (P<0.01) increased means of final body weight (FBW), red blood cells (RBCs), WBCs, Hg, HCT, MCV, TP and Alb, glucose and TAC than the corresponding means of the control group. While, the treatment with BP significantly (P<0.05) reduced TFI and serumcholestrol. The means of ejaculate volume, live sperms, mass motility, conc./ml and conc./Ej.(106)for bucks treated with BP exceeded significantly (P<0.01), while the reaction time and sperm abnormalities were significantly (P<0.01) decreased as compared with the corresponding figures in the control group. Similarly, the means of glutathione content (GSH) and testosterone hormone concentration were significantly increased in the treated bucks, while the mean malondialdehyde (MDA) was significantly decreased as compared with the control group. Conclusively, from the obtained results it could be concluded that treating rabbit bucks raised under high temperature with both of 500 and 1000mg/ buck significantly improved the semen characteristics, blood parameters, antioxidant activities, and testosterone hormone.

Gestating sows have greater digestibility of energy in full fat rice bran and defatted rice bran than growing gilts regardless of level of feed intake

Gestating sows have greater digestibility of energy in full fat rice bran and defatted rice bran than growing gilts regardless of level of feed intake

A meta-analysis of feeding sugar beet pulp in dairy cows: Effects on feed intake, ruminal fermentation, performance, and net food production

Feeding of industrial by-products such as sugar beet pulp (Bp) is an economically viable option in dairy production, but high inclusion rates might impair feed intake and performance of the cows. The present meta-analysis was performed to evaluate inclusion of Bp in dairy cow diets taking into account inclusion rate of Bp, feed intake and production levels of the cows, concentrate level in the diet and replacement aim of Bp (i.e., grain type and forage replaced). Effects on dry matter intake (DMI), ruminal fermentation, and milk production variables as well as on net food production, as a measure of sustainability, were determined using meta-analysis and meta-regression approaches. Data were extracted from 34 different studies published from 1990 to 2016, comprising a total of 103 dietary treatments. The effect of Bp on DMI depended largely (P=0.016) on the feed intake level of cows. DMI decreased with increasing Bp inclusion level in cows with a high feed intake level (>3.5% of BW), but not in cows with a low intake level (≤3.5% of BW), noted by an interaction between Bp level and feed intake level (P=0.015). Bp inclusion had no effect on milk yield (P=0.514) but increased milk fat yield (P=0.004) and fat-corrected milk yield (P=0.002). Effects of Bp on milk production variables were independent of the dietary concentrate level as well as the replacement aim. Ruminal pH increased (P=0.046) but only when Bp was fed at a level of >200g/kg of diet DM. There were interactions between the Bp inclusion and the dietary concentrate level for molar percentages of propionate (P=0.008) and butyrate (P=0.021) and, to a lesser extent, for acetate (P=0.057), with acetate and propionate being altered by Bp only in high concentrate diets. All variables related to net food production including kg milk/MJ human edible energy input (P=0.002) or g milk protein/g human edible protein input (P=0.027) were strongly improved by feeding of Bp. In conclusion, the effect of Bp as a feedstuff for dairy cows depends on the cow’s feed intake and production level, whereby high inclusion rates of Bp seem to be particularly beneficial in cows in which the feed intake level does not exceed 3.5% of BW.

Effects of dry matter and energy intake on quality of oocytes and embryos in ruminants.

The success of herd fertility involves the development of healthy follicles, viable oocytes and embryos capable of establishing and maintaining a pregnancy. Herein we discuss how nutrition interacts with reproduction throughout follicle development and pregnancy establishment, focusing on dry matter and energy intake. High feed intake, especially associated with moderate to high body condition, before and through superstimulation protocols, natural or induced single-ovulations or before ovum pick-up has detrimental effects on the quality of oocytes or embryos. Feed restriction or high energy supply can be used strategically to obtain either more or better quality oocytes or embryos. Altering diets that provide different concentrations of circulating insulin may improve ovarian status, oocyte quality, embryo development and pregnancy establishment and maintenance. Some sources of fat can positively affect reproductive performance, such as polyunsaturated fatty acids, improving embryo quality and pregnancy. In contrast, fat supplementation in the diet may compromise embryo cryotolerance. Finally, nutrition can alter concentrations of circulating or intrafollicular hormones and metabolites and the expression of genes in cattle oocytes and embryos. For an adequate feeding program to benefit reproductive performance, factors such as genetic group, source of energy, metabolic status, physiological status and level of feed intake must be taken into account.

Increased expressions of genes and proteins involved in mitochondrial oxidation and antioxidant pathway in adipose tissue of pigs selected for a low residual feed intake.

Adipose tissue is a primary sensor for nutrient availability and regulates many functions including feed intake and energy homeostasis. This study was undertaken to determine the molecular responses of adipose tissue to differences in feed intake and feed efficiency. Subcutaneous adipose tissue was collected from two lines of pigs divergently selected for residual feed intake (RFI), a measure of feed efficiency defined as the difference between actual and expected feed intake, and from a subset of high-RFI pigs that were feed-restricted at the level of the voluntary feed intake of low-RFI pigs during the growing-finishing period. Transcriptomics analyses indicated that the number of genes that were differentially expressed ( < 0.01) between low- and high-RFI pigs ( = 8 per group at each stage) in adipose tissue was much lower when pigs were considered at 19 kg (postweaning) than at 115 kg BW (market weight). Extended investigations were performed at 115 kg BW to compare low-RFI ( = 8), high-RFI ( = 8), and feed-restricted high-RFI ( = 8) pigs. They included in silico pathway analyses of the differentially expressed (DE) genes ( < 0.01) and a complementary proteomic investigation to list adipose proteins with a differential abundance ( < 0.10). Only 23% of the DE genes were affected by both RFI and feed restriction. This indicates that the responses of adipose tissue to RFI difference shared only some common mechanisms with feed intake modulation, notably the regulation of cell cycle (including ) and transferase activity pathway. Two carboxylesterase genes (, ) involved in lipolysis, were among the most overexpressed genes in the low-RFI pigs; they were also affected by feed restriction within the high-RFI line. About 60% of the molecular changes between low- and high-RFI pigs were specific to genetic divergence in feed efficiency, independently of feed intake. Different genes and proteins known to be associated with mitochondrial oxidative metabolism were overexpressed in adipose tissue of low-RFI pigs compared with high-RFI pigs; other proteins participating in the generation of energy were also affected by feed restriction within the high-RFI line. Finally, mitochondrial antioxidant genes were upregulated in low-RFI pigs vs. high-RFI pigs. Altogether, increased oxidative and antioxidant processes in adipose tissue might be associated with improved feed efficiency.

Определение зависимости уровня потребления корма от функционально-технологических показателей рецептурной смеси

Определение зависимости уровня потребления корма от функционально-технологических показателей рецептурной смеси

Effects of feed intake and dietary nutrient density on apparent ileal and total tract digestibility of nutrients and gross energy for growing pigs.

The present study was conducted to investigate the effects of feed intake (FI) and dietary nutrient concentration on the determination of apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and GE for growing pigs. A total of 48 growing pigs (40.7 ± 1.3 kg initial BW) were surgically fitted with simple T-cannulas at the distal ileum and assigned to 6 treatment groups in a 2 × 3 factorial arrangement of 2 diets (a low-nutrient-density [LND] diet or a normal-nutrient-density [NND] diet) and 3 FI levels (3, 4 or 5% of BW per day). The experimental period consisted of a 5-d adjustment period: 2 d of feces collection (on d 6 and 7), and 2 d of ileal digesta collection on (d 8 and 9). Chromic oxide was used as an indigestible marker to calculate AID of AA and AID and ATTD of CP, ether extract (EE), ash, ADF, NDF, total carbohydrates (CHO), and GE. The AID of CP ( < 0.05), EE ( < 0.1), ash ( < 0.05), and GE ( < 0.1); the ATTD of ash ( < 0.1); and the hindgut disappearance of CP ( < 0.05), ash ( < 0.1), and most AA were affected by the interaction of dietary nutrient density and FI level. The AID of CP and the AID and ATTD of DM, EE, CHO, and GE linearly decreased for pigs fed a NND diet as FI increased ( < 0.05). Furthermore, the AID of CHO ( < 0.1) and NDF ( < 0.05), the ATTD of DM ( < 0.1), and the hindgut disappearance of CHO and NDF ( < 0.1) were influenced by FI. When pigs were fed the NND diet, the AID of most AA decreased (linear, < 0.05) with increasing FI. However, there were no linear or quadratic effects of FI levels on the AID, ATTD, and the hindgut disappearance of DM, CP, EE, CHO, NDF, ADF, and GE and the AID of most AA for pigs fed the LND diet. In summary, the AID and ATTD of nutrients and GE response of growing pigs to FI levels are dependent on dietary nutrients density. The AID and ATTD of nutrients and GE decreased for pigs fed the NND diet as FI increased.

The oxygen threshold for maximal feed intake of Atlantic salmon post-smolts is highly temperature-dependent

In order to maximize the growth potential of Atlantic salmon (Salmo salar L.) in the on-growing phase in open sea cages, the dissolved oxygen (DO, % of air saturation) level must exceed the minimum DO required for maximal feed intake (DOmaxFI). The main aim of this study was to determine the effect of temperature on this important threshold DO, and secondly, to provide aquaculturists with a model that estimates feed intake as function of both temperature and DO. Quadruple tank groups of Atlantic salmon post-smolts (~0.3–0.5kg) were kept at 7, 11, 15 and 19°C, and subjected to seven DO levels per temperature, ranging from ≈32–92, 42–102, 52–112 and 62–122% O2, respectively, for 42days. DO levels were changed every second day, in random order. Fish were fed a known amount of feed in excess twice daily, waste feed was collected and daily feed intake (DFI, % of biomass, BM, per day) estimated. The routine oxygen consumption rate (MO2 rout, measured in partially fasted and active fish) and the DO below which MO2 rout started to decline (termed the routine limiting oxygen saturation, LOSrout) was determined in fasted fish at all four temperatures at the end of experimentation, and the latter was used to estimate the “zero feed intake DO” in the DFI model. The data demonstrate sustained appetite with decreasing DO until a threshold level (DOmaxFI) is reached, at which point appetite gradually decreases. Both the maximal level of feed intake (DFImax) and the DOmaxFI were highly dependent on temperature, increasing from 0.47 to 0.88% of BM/day, and from 42 to 76% O2, respectively, within the temperature range tested. The LOSrout ranged from 24 to 40% O2. The present study is the first to present the pronounced effect of temperature on DOmaxFI, and results suggest that the DO requirement of A. salmon has previously been considerably over-estimated, particularly at lower temperatures. Statement of relevanceThe study links growth performance to environmental temperature and oxygen.