Incorporation of sunflower oil or linseed oil in equine compound feedstuff: 1 Effects on haematology and on fatty acids profiles in the red blood cells membranes.

Eight trained horses (6 mares - 2 geldings, 6 Selle Français, 2 Trotteur Français, 12 ± 5.8 years old, 538 ± 72.5 kg) were offered three diets to potentially affect haematology and the fatty acids (FA) profiles in red blood cells (RBC) membranes. The control diet was composed of 50% hay and 50% concentrate containing mainly rolled barley (48%) and whole spelt (48%). In the case of sunflower oil diet, sunflower oil (62.0% of α-linoleic acid, LA) was incorporated at a rate of 8% and substituted by an equal proportion of barley. In the linseed oil diet, first cold-pressed linseed oil (56.0% of α-linolenic acid, ALA) was utilised at a similar incorporation rate of 8%. The experimental design consisted of three 3 × 3 latin squares with one being incomplete. Each period lasted 8 weeks. On average, the total feed intake (straw excluded) was 6.2 kg/day and the oil intake 0.278 kg/day. The oils significantly increased the concentrations of RBC, haemoglobin and haematocrit. The oils had no significant impact on the haematology profiles except that platelets tended to decrease in both oil-based diets. The most abundant FA in the RBC membranes of the control diet samples were in the decreasing order LA, C18:1n9-7, C18:0, C16:0 and the arachidonic acid (ARA) respectively. The sunflower oil supplementation slightly increased the amount of LA (36.23 vs. 34.72 mg/dl, p = 0.55) and C22:4n-6 (0.21 vs. 0.09 mg/dl, p = 0.22), while the decrease was observed in case of other FA (C16:1n-7, 1.08 vs. 1.42 mg/dl, p = 0.03), C20:3n-6 (0.22 vs. 0.31 mg/dl, p = 0.02), and ARA (1.17 vs. 1.63 mg/dl, p = 0.08). Linseed oil induced similar effects in the n-6 series FA profiles. In the context of practical applications, our results show that linseed oil incorporation in the diet could improve the haematology and the n-3 FA profiles potentially leading to an increased performance.

Dietary incorporation of feedstuffs naturally high in organic selenium for racing pigeons (Columba livia): effects on plasma antioxidant markers after a standardised simulation of a flying effort.

Selenium is a trace element of importance for animal health. It is essential for adequate functioning of many enzymes such as, the antioxidant enzyme, glutathione peroxidase, which protects the cell against free radicals. A muscular effort induces a rise in reactive oxygen species production which, in turn, can generate an oxidative stress. Two groups of eight racing pigeons were fed respectively with a diet containing 30.3 (control group) and 195.3 (selenium group) microg selenium/kg diet. The pigeons were submitted to a standardised simulation of a flying effort during 2 h. Blood was taken before and after the effort to measure antioxidant markers and blood parameters related to muscle metabolism. Plasma selenium concentration and glutathione peroxidase activity were significantly higher in the selenium group. There were no significant differences for the other measured parameters. As a consequence of the effort, the pigeons of the selenium group showed a higher increase of glutathione peroxidase activity and a smaller increase of plasma lactate concentration. Variations because of the effort in the other markers were not significantly different between the two groups. It is concluded that the selenium status was improved with the feeding of feedstuffs high in Selenium.

Spelt, an ancient cereal and first pressure linseed oil as ingredients of compound feedstuffs for modern horse feeding.

Spelt is a covered cereal with large glumellas. In experiment 1, it has been compared in terms of chemical composition with barley, oat and maize. Spelt is characterized by rather low protein and ether extract (EE) contents. The neutral detergent fibre (NDF) content of spelt was slightly higher than that of oat but the acid detergent fibre (ADF) content was lower. Two compound feedstuffs were fed along with hay to six horses used in a cross-over design. Both diets were well appreciated by the horses and there were no significant differences in the apparent digestibility coefficients, except for EE which was significantly higher, when oat was included in the compound feedstuff. In experiment 2, first pressure linseed oil was incorporated at a rate of 8% in a control compound feedstuff, where the barley was partly substituted by the oil. The fat content was 9.6% dry matter (DM) in the linseed oil compound feedstuff and 5.4% in the hay-concentrate ration. The inclusion of linseed oil increased the digestibility of DM, EE and NDF of the diet. There were no effects on the post-prandial concentrations of glucose, triglycerides and non-esterified fatty acids (NEFA) but the insulin concentration was significantly reduced with the linseed oil inclusion. There were significant increases in the plasma concentrations of the total fatty acids, polyunsaturated fatty acids (PUFA), saturated fatty acids (SFA), C18:3 n-3 and C18:2 n-6 and significant reductions in the contents of monounsaturated fatty acids (MUFA), C18:1 n-7 + n-9 and C20:4 n-6. It is concluded that the inclusions of spelt and first pressure linseed oil in compound feed stuff for horse are of interest for modern horse feeding.

Relationship between leptin content, metabolic hormones and fat deposition in three beef cattle breeds.

The aim of the study was to determine if cattle breeds differing in their carcass characteristics also differ in the profiles of their leptin and metabolic hormones. Three breeds, Belgian Blue (BB) (n=12), Limousin (L) (n=12) and Aberdeen Angus (AA) (n=12) with varying ability to deposit fat and protein were compared. Blood, muscle and subcutaneous (SC) adipose tissue were sampled. Animal performance, carcass and meat characteristics were determined as well as plasma leptin concentration, leptin gene expression in SC adipose tissue, leptin-receptor gene expression in SC adipose tissue and plasma concentration of insulin, tri-iodothyronin (T3), thyroxin (T4) and cortisol. The BB bulls showed the lowest values of leptin gene expression (P<0.05). Values of plasma leptin concentration and of leptin-receptor gene expression tended to be lower in BB than in the other breeds. For a similar amount of adipose tissue (after normalisation), BB bulls showed a higher ratio of plasma leptin (P<0.05), whereas normalised leptin gene and leptin-receptor gene expressions did not significantly differ between breeds. Belgian Blue bulls also differed in their metabolic hormone profile, tending to show lower values of insulin, T3 and T4 than the two other breeds. Cortisol levels were significantly lower (P<0.05) in BB than in L and AA animals.

Analysis of 4495 canine and feline uroliths in the Benelux. A retrospective study: 1994-2004.

From 1994 to 2004, Hill's Pet Nutrition received 4495 canine (65%) and feline (35%) uroliths from Benelux veterinary practitioners. They were sent to the Minnesota Urolith Center, USA for analysis. In 1994, 110 uroliths were analysed - 85% from dogs - and in 2003, 1067 uroliths were analysed - 59% from dogs. During this period, substantial changes were observed in composition. In 1994, 77% of the cats had uroliths composed of struvite, and 12% had uroliths composed of calcium oxalate. In 2003, feline uroliths were composed of 32% struvite, and 61% calcium oxalate. The same evolution was observed in the dogs. In 1994, 51% of canine uroliths were composed of struvite, and 33% of calcium oxalate. In 2003, 40% had struvite uroliths, and 46% had calcium oxalate uroliths. A significant effect of the size, the breed, and the gender were noticed in the dogs. The mean age of uroliths appearance was 7.3 years in the dogs and 7.2 years in the cats. The findings are similar to those previously published in the USA.

Effect of ovariectomy and ad libitum feeding on body composition, thyroid status, ghrelin and leptin plasma concentrations in female dogs.

The objective of this study was to evaluate the effects of ovariectomy (i) and ad libitum feeding (ii) on energy intake, body weight (BW), body composition, thyroid status, leptin and ghrelin plasma concentrations. Four young adult female Beagle dogs were fed a maintenance diet for 6 weeks prior to ovariectomy, then 6 months after. Food allowance was adjusted in order to maintain optimal BW. Then, a diet slightly higher in energy concentration was fed ad libitum for 4 months. The maintenance diet was then fed ad libitum for one additional month. The maintenance of optimal BW after ovariectomy required a significant decrease in energy allowance. No increase in fat mass was observed. Ghrelin concentration remained unchanged. During the first month of ad libitum feeding, plasma ghrelin concentration and energy intake increased, then they decreased. Mean BW, plasma leptin, thyrotropin (TSH), total triiodothyronine (TT3) and total thyroxine (TT4) concentrations significantly increased over the study. The BW increase was exclusively due to an increase in body fat. In conclusion, energy allowance should be strictly controlled in spayed female dogs. The results suggest that in dogs, thyroid hormones, leptin and ghrelin concentrations change in response to a positive energy balance in an attempt to limit weight gain. However, the significant weight gain shows that this goal was not achieved.

Comparison of composition and quality traits of meat from young finishing bulls from Belgian Blue, Limousin and Aberdeen Angus breeds.

Thirty-six young finishing bulls from three breeds (Belgian Blue, Limousin and Aberdeen Angus) were fattened over five months with finishing diets based either on sugar-beet pulp or on cereals. Nutritional quality traits of meat - fat content and fatty acid composition with emphasis on the n-6 and n-3 polyunsaturated fatty acids - along with some organoleptic quality traits were measured. The Belgian Blue bulls had the lowest intramuscular fat content associated with lower saturated and monounsaturated fatty acid contents. The polyunsaturated fatty acid content did not differ to a large extent between the breeds, the Aberdeen Angus bulls showing slightly higher values. Relative to energy intake, the overall contribution of meat to the n-3 fatty acid recommended intake was small, whatever the breed. By contrast, the contribution of meat to daily fat intake was of greater importance, especially for the Aberdeen Angus bulls. The quality traits of meat varied also according to the breed: compared to the Aberdeen Angus, the Belgian Blue bull meat had the stablest colour, the highest drip and the lowest cooking losses. The meat of Limousin bulls had intermediate characteristics for all the parameters.

Variation of plasma parameters and nitrogen metabolism in finishing Belgian blue double-muscled cull females.

The changes over time in plasma parameters and nitrogen metabolism were studied in finishing Belgian Blue double-muscled females offered a maize silage based diet. When compared with literature data, plasma glucose along with triglycerides concentrations was low while non-esterifled fatty acids were high and rich in polyunsaturated forms. The concentrations in thyroid hormones, insulin-like growth factor 1 and insulin were also low and plasma insulin decreased with time. Growth hormone concentration, by contrast, increased with time. On average, the females retained 44 g nitrogen per day from an intake of 210 g but the efficiency of retention decreased with time. The fractional rates of accretion and synthesis of muscle protein were also affected by time. The dry matter content in muscle biopsies was close to 22% and increased with the finishing, as did the diameter of the tailhead adipocytes.

Hypercholesterolaemia in a family of rough collie dogs.

A family of five privately owned rough collie dogs was referred for corneal lipidosis and also suffered from hypercholesterolaemia. The hypercholesterolaemia was characterised by an increase in the alpha-2 high density lipoprotein-1 band and was due to an increase in the cholesterol content of the very low density lipoprotein, low density lipoprotein and possibly the high density lipoprotein-1 fractions. A low-fat and energy-restricted diet did not reduce either total cholesterol or the corneal lipidosis. Corneal lipidosis regressed with short-chain fructo-oligosaccharide supplementation. However, the effects of short-chain fructo-oligosaccharides on total cholesterol were transient and variable.

Ad libitum feeding following ovariectomy in female Beagle dogs: effect on maintenance energy requirement and on blood metabolites.

The aim of this study was (i) to evaluate the effect of ovariectomy on daily energy requirement in Beagle dogs, and (ii) to evaluate the effects of ad libitum feeding with a high energy diet on energy consumption, body weight gain and blood metabolites in these spayed dogs. Four young adult female Beagle dogs were used. Ovariectomy induced a significant decrease of daily energy requirement in dogs. Ad libitum feeding, initiated 6 months after spaying, induced a significant increase in consumption in spayed dogs. This overconsumption was greatest during the first month of ad libitum feeding but continued for the entire 4 months of this period. When fed ad libitum, dogs gained excess body weight without significant effect on plasma cholesterol, triglycerides, glucose and insulin, at short term. These data suggest that energy intake should be strictly controlled to avoid excess weight gain in spayed dogs.

Evolution of blood parameters during weight loss in experimental obese Beagle dogs.

The effects of weight loss on hormonal and biochemical blood parameters were measured monthly [carnitine, creatinine, urea, free T4 (fT4), total T4 (TT4), plasma alkaline phosphatases (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), potassium and total proteins] or bimonthly [cholesterol, triglycerides, non-esterified fatty acids (NEFA), insulin-like growth factor I (IGF-I), glucose, insulin] in eight obese Beagles dogs fed either a high protein dry diet, DP (crude protein 47.5%, on dry matter basis) or a commercial high fibre diet, HF (crude protein 23.8%, crude fibre 23.3%). The dogs were allotted to two groups according to sex and body weight (BW) and they were respectively fed with the DP or the control HF diet during 12-26 weeks, until they reach their optimal BW. The plasma basal triglycerides and cholesterol concentrations were decreased by the two diets but the difference was only significant for the DP diet. The plasma mean NEFA concentration increased regularly over the period with the HF diet, without significant difference between the two diets. No effect of diet or weight loss was observed on plasma carnitine, urea, creatinine, ALP, AST, ALT, potassium, TT4, FT4, IGF-I, glucose and insulin. Weight loss induced a decrease in fT4 plasma concentration (p < 0.001). The high protein diet allowed a safe weight loss.

Prediction of technological and organoleptic properties of beef Longissimus thoracis from near-infrared reflectance and transmission spectra.

Technological and organoleptic properties of beef cuts were predicted by near-infrared (NIR) spectroscopy. Spectra were collected on 189 beef Longissimus thoracis muscle samples using, transmission (NIRT) and reflectance with a probe. Quality assessment and NIR recordings were performed on sliced loin after 2 and 8 days ageing. Partial least squares regression yielded determination coefficients of cross-validation (R(2)(cv)) of 0.12-0.25 for the prediction of Warner-Bratzler Peak Shear Force in reflectance and 0.15-0.41 in transmission. Higher R(2)(cv) were obtained for L* parameter (0.83-0.85), a* (0.39-0.49) and b* (0.73-0.75) with reflectance. Predictions of drip loss and cooking loss were less accurate with a R(2)(cv) range of 0.38 to 0.54 and 0.25 to 0.47, respectively. The NIR spectra collected on fresh meat show good potential to predict CIE L* and b* parameters in reflectance mode.

The course of some bone remodelling plasma metabolites in healthy horses and in horses offered a calcium-deficient diet.

An inquiry was carried out to assess the concentrations of plasma metabolites related to bone remodelling in 21 saddle horses of Warmblood breed aged 4-26 years, five draught horses of Ardennes breed aged 4-10 years, and 10 Ardennes foals aged 9-11 months. They were fed according to normal feeding practice in Belgium. The changes in some bone remodelling plasma metabolite concentrations were studied when an unbalanced diet was offered and later corrected for four Warmblood horses. Bone formation was evaluated by bone alkaline phosphatase (BALP), total alkaline phosphatase (TALP) and osteocalcin (bone gla-protein, OC). Bone resorption was assessed by hydroxyproline (HYP). Total calcium, ionized calcium, phosphorus (P) and 25-hydroxyvitamin D3 [25-(OH)D] concentrations were more or less constant. The comparison of four bone remodelling factors between the Ardennes and Warmblood horses showed higher concentrations in the Ardennes breed. Bone marker concentrations decreased according to age. The correction of the unbalanced Ca : P diet induced inconsistent effects at plasma level. The interpretation of the different bone parameters appeared to be difficult if not associated with other parameters such as a complete anamnesis and clinical examination of the animal in addition to dietary evaluation.

Prediction of protein digestibility in dog food by a multi-enzymatic method: a useful technique to develop.

The multi-enzymatic method with constant pH described by Dufour-Etienne et al. (Rec. Méd. Vét. 168, 789-796, 1992) was tested using 17 industrial dry dog foods and two ingredients, sodium caseinate and beef meat, which were used as references. The quantity of sodium hydroxide added to the enzymatic solution was measured after incubation times of 2, 5 and 10 min and the best prediction of the apparent protein digestibility was obtained with an incubation time fixed at 2 min. The volume of sodium hydroxide 0.1 N constantly added to maintain the pH of the solution at 8 was correlated to the value of in vivo digestibility of the protein measured in the dog. The correlation coefficient obtained was 0.90 with a standard error of the regression of 1.9 for all samples. The correlation coefficients calculated for incubation times of 5 and 10 min were lower than that at 2 min; thus an incubation period of 2 min provided the highest correlation coefficient for this multi-enzymatic method at constant pH. However, considering the lack of samples with an apparent protein digestibility ranging between 85 and 95%, the slope of the regression line and the correlation coefficient were strongly influenced by the ingredients, such that when the correlation coefficient was calculated for 17 dog foods without the reference ingredients, a coefficient of 0.71 (+/- 1.9) was obtained. These tests of in vitro digestibility are valuable to predict the apparent digestibility of the protein in the dog, but, it is essential to confirm the results by an in vivo test.

Mechanisms of reduced and compensatory growth.

Growth is an integrated process, resulting from the response of cells dependent on the endocrine status and nutrient availability. During feed restriction, the production and secretion of growth hormone (GH) by the pituitary gland are enhanced, but the number of GH receptors decreases. Changes of GH binding proteins induce GH resistance and are followed by reduced insulin-like growth factor-I (IGF-I) secretion. On the other hand, high circulating levels of GH enhance the mobilization of fatty acids, which are used to support energy requirements. Thus, when feed restriction in growing animals is moderate, there is mainly protein but barely fat accretion. By contrast, a severe feed restriction enhances the release of catabolic hormones and stimulates, from muscle cells, the liberation of amino acids, which are used by hepatocytes for gluconeogenesis. During refeeding and compensatory growth, the secretion of insulin is sharply enhanced and plasma GH concentrations remain high. This situation probably allows more nutrients to be used for growth processes. The role of plasma IGF-I during compensatory growth is not clear and must be explained in connection with changes of its binding proteins. Thyroxin and 3,5,3'-triiodothyronine seem to have a permissive effect on growth. The simultaneous occurrence of puberty with refeeding can exert a synergistic effect on growth. Initially, compensatory growth is characterized by the deposition of very lean tissue, similar as during feed restriction. This lasts for some weeks. Then, protein synthesis decreases and high feed intake leads to increased fat deposition.

Feed restriction in young bulls alters the onset of puberty in relationship with plasma insulin-like growth factor-I (IGF-I) and IGF-binding proteins.

The objectives of this study were to evaluate the effect of feed restriction and re-alimentation on the onset of puberty and IGF status in peripubertal male calves and to compare the radioimmunoassay (RIA) and western ligand blotting (WLB) methods for bovine IGFBP-2. Twelve prepubertal 290 d-old Belgian Blue bulls (mean weight: +/- 290 kg) were randomly assigned in three groups: a control group (NG; n = 4) receiving a classic fattening diet to induce "normal" growth (1.48 kg/d), a feed restricted group (RG; n = 4) to obtain reduced growth (0.50 kg/d) and, a severely restricted group (SG; n = 4) to nearly stop growth (0.08 kg/d). The feed restriction period was maintained over a period of 114 d. After the period of differential feeding, all animals received the control feed regime over a period of 100 d. Blood samples were collected at fortnightly intervals. Circulating IGF-I was measured by RIA whereas plasma IGFBPs was evaluated by WLB; IGFBP-2 was additionally quantified by RIA procedure. At the beginning of the trial, IGF-I levels were low (<100 ng/ml) and similar in the three groups in accordance with prepubertal status. In the NG group, a progressive rise in IGF-I was observed from Day 42 to Day 142 whereas in the RG and SG groups, IGF-I levels did not change until the experimental restriction period ended. The delay of the rise in plasma IGF-I was longer for the SG group, IGF-I remained low until 2 wk after the end of the period of restricted feeding. Surprisingly, although differences were detected for IGF-I levels between the three groups, the IGFBP-2 and -3 data, evaluated by WLB could only discriminate between NG and SG group and not between NG and RG. However, by using a RIA method, an IGFBP-2 decrease was observed in the NG group coincident with increasing IGF-I levels. For both RG and SG groups, IGFBP-2 levels remained high throughout the feed restriction period whereas plasma IGFBP-2 levels declined upon feeding in both groups. During this feed restriction period, IGFBP-2 was significantly lower in NG than in RG or SG groups. Moreover, SG group animals had higher levels in plasma IGFBP-2 than RG animals. In conclusion, puberty is characterized by developmental changes in plasma IGF-I and IGFBPs that were altered by feed restriction. Moreover, RIA evaluation of plasma IGFBP-2 is able to better reflect group differences than WLB.

A homologous radioimmunoassay for quantification of insulin-like growth factor-binding protein-2 in blood from cattle.

Insulin-like growth factor-I and -II (IGF-I, IGF-II) circulate in biological fluids bound to six different IGF-binding proteins that regulate IGF bioactivity. The IGF-binding protein-2 is regulated by growth hormones, and its concentration depends on nutrition and physiological state. Specific antibodies directed against bovine IGF-binding protein-2 were produced, and IGF-binding protein-2 levels in bovine blood samples were quantified by radioimmunoassay. Parallel displacement curves showed strong cross-reactivity with bovine and ovine plasma, were low with porcine plasma, and no cross-reactivity with rat or chicken plasma. Addition of IGF-I or -II to a control pool of bovine plasma did not significantly alter control IGF-binding protein-2 values in a radioimmunoassay. Six nycthemeral periods, determined for three young bulls bled on two occasions, showed that IGF-binding protein-2 plasma levels were stable throughout the day; two or three samples were sufficient to characterize the animal. Cows treated with recombinant bovine somatotropin (bST) had significantly lower serum levels of IGF-binding protein-2 than did control cows. Furthermore, IGF-binding protein-2 levels were dramatically increased at the onset of lactation. This radioimmunoassay for bovine IGF-binding protein-2, which enables quantitative assessment of IGF-binding protein-2 concentration in cattle, confirmed that IGF-binding protein-2 concentrations are depressed by administration of bST, enhanced after calving, and showed absence of diurnal variation.

The influence of sugar-beet fibre, guar gum and inulin on nutrient digestibility, water consumption and plasma metabolites in healthy Beagle dogs.

The aim of the present study was to evaluate the effects of three fibres (sugar-beet fibre, guar gum and inulin) incorporated in the basal diet of healthy dogs at 7 per cent of dry matter (DM). Parameters examined included stool output, water consumption, nutrient digestibility and fasting and postprandial plasma metabolites. All fibres increased wet faecal output; an increase in faecal DM output being observed with sugar-beet fibre only. Sugar-beet fibre and inulin increased daily water consumption. Sugar-beet fibre and guar gum decreased DM digestibility. The three fibres diminished organic matter and crude protein digestibility while ether extract digestibility was decreased by guar gum and inulin. Guar gum induced lower postprandial insulin, alpha-amino-nitrogen and urea plasma concentrations. Guar gum also lowered fasting cholesterolaemia. Sugar-beet fibre and inulin showed no metabolic effects. These physiological properties suggest that guar gum would be a suitable ingredient for dietary therapy of chronic diseases such as diabetes mellitus or hyperlipidaemia in the dog.

Different periods of feed restriction before compensatory growth in Belgian Blue bulls: I. animal performance, nitrogen balance, meat characteristics, and fat composition.

Thirty double-muscled Belgian Blue bulls were maintained at a rate of gain of .5 kg/d during four periods of time, 115 (G2), 239 (G3), or 411 (G4) d (low growth period, LGP), before fattening (rapid growth period, RGP). Ten control animals (CG) were fed a diet rich in energy and protein. The G2, G3, and G4 were fed a diet low in energy and protein and the same diet as CG during RGP. Live weight was recorded biweekly, feed intake (FI) daily, and nitrogen balance at three times for each group. At the slaughterhouse, the 7, 8, and 9th ribs were removed to determine carcass composition, meat quality, and meat and fat composition. Compensatory growth reached a maximum 2 mo after refeeding and then decreased rapidly, leading to a sharp increase in the feed conversion ratio. Nitrogen balance was higher in compensating groups ( P < .05). Compensating animals had higher carcass connective and adipose tissue contents (P < .05) but lower meat fat content (P < .05). Cattle exhibiting compensatory growth had higher redness, yellowness, cooking losses, and drip losses, but had lower Warner-Bratzler peak shear force values. The saturated fatty acid content of the fat decreased with the duration of the LGP. During the first 2 mo after refeeding, compensatory growth in double-muscled bulls was ascribed to one or more of the following mechanisms: higher FI, lower maintenance requirements, or better efficiency of lean meat production. Compensatory growth at the expense of higher FI increased peripheral fat but decreased intramuscular fat deposition.

Different periods of feed restriction before compensatory growth in Belgian Blue bulls: II. Plasma metabolites and hormones.

Plasma metabolites and hormones were studied in 16 double-muscled Belgian Blue bulls maintained at low growth (.5 kg/d) for 114 (G2), 243 (G3), or 419 (G4) d (low growth period, LGP) before fattening (rapid growth period, RGP). Animals from the control group (CG) were fed a diet high in energy and protein. The animals from G2, G3, and G4 were fed a restricted amount of a diet low in energy and protein during LGP and the same diet as CG during RGP. Plasma glucose, alpha-amino nitrogen (AAN), NEFA, urea, creatinine, thyroxine (T4), 3,3',5'-triiodothyronine (T3), and IGF-I were measured in blood samples taken fortnightly. Plasma GH and insulin (I) profiles were measured in serial blood samples obtained at three times during growth. The RGP was characterized by an initial compensatory growth, by higher plasma glucose, AAN, and urea levels, and by lower plasma NEFA and creatinine levels. Plasma GH concentration decreased after refeeding. Plasma T4 increased linearly during refeeding, as opposed to T3, which showed a different profile in each group. Plasma IGF-I showed a curvilinear increase during RGP and reached a plateau after 3 mo in each compensating group. In G4, changes of plasma metabolites and hormones differed often distinctly from G2 or G3. During refeeding, higher nutrient supply improved the functionality of the somatotropic axis and increased the concentration of anabolic hormones, allowing rapid muscle deposition. However, animals underfed the longest period behaved differently from the other groups, possibly because they reached a more complete sexual maturity.