Influence of dietary protein level on body composition and energy expenditure in calorically restricted overweight cats

High‐protein (HP) diets help prevent loss of lean mass in calorie‐restricted (CR) cats. However, it is not entirely known whether these diets also induce changes of energy expenditure during periods of CR. To investigate this issue, sixteen overweight cats were fed either a high‐protein [(HP), 54.2% of metabolizable energy (ME)] or a moderate‐protein [(MP), 31.5% of ME] diet at 70% of their maintenance energy intakes for 8 weeks, and energy expenditure, energy intake, body weight and composition, and serum metabolites and hormones were measured. While both groups of cats lost weight at a similar rate, only cats eating the HP diet maintained lean mass during weight loss. Indirect respiration calorimetry measurements revealed that both total and resting energy expenditure (kcal/d) significantly decreased during weight loss for both treatment groups. However, only cats eating the MP diet exhibited significant decreases of total and resting energy expenditures after energy expenditure was normalized for body weight or lean mass. Results from this study suggest that in addition to sparing the loss of lean mass, feeding HP diets to overweight cats in restricted amounts may be beneficial for preventing or minimizing decreases of mass‐adjusted energy expenditure during weight loss.     

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth

The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.     

A first estimate of the amino acid requirement for milk production of the high-producing female mink (Mustela vison)

Thirty mink dams nursing litters of six kits were assigned to one of three dietary treatments [high protein (HP), medium protein (MP) and low protein (LP)], fed ad libitum for 4 week from parturition, to investigate the effects of protein supply on milk yield and milk composition in order to estimate the amino acid requirement of the lactating mink. Twelve dams were held in an intensive care unit and subjected to balance experiments and the kits were injected with deuterium oxide to determine water kinetics and milk yield. Eighteen dams were kept under normal farm conditions but with feed intake of dams and live weight gain of kits being determined and milk samples collected. The ME intake was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet, whereas the amino acid intake (g/day) was lowest (p < 0.05) in dams fed the LP diet. In the third and fourth weeks of lactation milk yield was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet. Chemical composition of milk was not affected (p > 0.05) by dietary treatment. However, protein content tended (p = 0.06) to be lower in dams fed the LP diet. Amino acid content (g/16 g N) of milk was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet. This resulted in the highest (p < 0.05) amino acid intake and highest (p < 0.001) live weights of kits nursed by dams fed the LP and MP diets, which may be explained by a combined effect of higher ME intake and reduced energetic costs for glucose production through less amino acids being used in gluconeogenesis. In conclusion, the improved performance of dams fed the LP diet suggested that their requirement of essential amino acids and non-specific N were covered, and the requirement of digestible amino acids of lactating mink (kg(0.75)) was, thereby, estimated by use of a factorial approach including the amino acid excretion in milk of LP dams.     

Effect of dietary linoleic acid concentration and vitamin E supplementation on cell desquamation and susceptibility to oxidative damage of pig jejunal mucosa

Sixty Large White × Great York pigs weighing approximately 60 kg were individually fed on six experimental diets. The experiment was organized in a 3 × 2 factorial arrangement design with three different fat sources and a basal or supplemented (200 mg/kg diet) level of α-tocopheryl acetate. All diets contained the same concentration of saturated fatty acids (15 ± 0.2 g/kg dry matter) but differed in the concentration of C18 : 2 (14 ± 0.5, 18 ± 0.4 and 21 ± 0.6 g/kg) and monounsaturated fatty acids (19 ± 0.2, 15 ± 1.2 and 10 ± 1.3 g/kg). No effect of dietary treatment was observed on weight gain and feed consumption. A histological study of the jejunal mucosa showed lower cell desquamation in groups containing a supplemental level of α-tocopheryl acetate (p=0.080). A higher cell desquamation was found in the groups fed diets containing the higher concentration of C18 : 2 (p=0.087). We also observed an interaction effect (p < 0.001) of dietary fat source and vitamin E supplementation on jejunal cell desquamation in which the effect of dietary vitamin E was lower when diets with a low concentration of C18 : 2 were administered. In vitro- induced oxidation of jejunal mucosa homogenates was lower in pigs fed diets supplemented with α-tocopheryl acetate (p < 0.002). The dietary concentration of C18 : 2 significantly affected oxidation of pig jejunal mucosa (p < 0.002).     

Effects of dietary protein content on renal parameters in normal cats

This study evaluates the effect of dietary protein content on renal parameters in 23 healthy spayed female cats. The objective was to determine if cats eating diets high in protein will have higher serum urea nitrogen (UN) and creatinine values without a detectable change in kidney function, as assessed by urinalysis. A single random cross-over design was used. Cats were fed a standard maintenance diet for at least 1 month prior to the dietary trial. They were fed in two phases. For the first phase, cats were randomly assigned to receive either a high protein [HP=46% metabolizable energy (ME)] or low protein (LP=26% ME) diet. For the second phase, cats were fed whichever diet they were not fed during the phase I period. Blood and urine samples were collected at 2-week intervals for the duration of the study (10 weeks). UN, albumin, alanine aminotransferase and urine specific gravity were significantly higher, and creatinine and phosphorus were significantly lower (P<0.05) when cats were fed the HP diet as compared to when they were fed the LP diet, although none of the mean values were found to be outside of the corresponding reference interval. Dietary intake can result in clinically significant changes in UN and statistically significantly changes in several other biochemical analytes, although all analytes are likely to remain within normal reference intervals. Therefore, an accurate dietary history is necessary to help determine if renal parameters are being influenced by diet in a particular patient.     

Interactions of amino acids and hormones regulate the balance between growth and milk protein synthesis in lactating rats fed diets differing in protein content

Insulin-like growth factor-I (IGF-I), growth hormone (GH), and prolactin (PRL) play important roles in milk protein synthesis, and their plasma concentrations were reported to be affected by dietary protein intake. To investigate the relationship between circulating amino acid (AA) and concentrations of these hormones, 18 Wistar rats aged 14 wk were assigned to a low (LP; 9% protein), standard (SP; 21% protein), or high-protein (HP; 35% protein) diet from parturition through day 15 of lactation. Plasma, liver, pituitary gland, skeletal muscle, and mammary gland samples were collected at the end of treatment. Circulating and hepatic IGF-I concentrations increased linearly with elevated dietary protein concentrations (P < 0.0001). Rats receiving the HP diet had higher circulating GH (P < 0.01) and pituitary PRL concentrations (P < 0.0001) but lower pituitary GH concentration (P < 0.0001) relative to those in rats receiving the LP and SP diets. Pearson correlation test performed on composed data across treatments showed that several circulating AAs were correlated with circulating and tissue concentrations of IGF-I, GH, and PRL. Multiple linear regression analyses identified Leu, Gln, Ala, Gly, and Arg as the main AAs associated with hormone responses (R² = 0.37 ~ 0.80; P < 0.05). Rats fed the LP and HP diets had greater Igf1 and Ghr gene expression in skeletal muscle than those fed the SP diets (P < 0.01). However, LP treatment decreased Prlr mRNA abundance in mammary glands as compared with the SP and HP treatments (P < 0.05). The HP diets increased AA transporter expression (P < 0.01) but decreased mammalian target of rapamycin (P < 0.05) and 70 kDa ribosomal protein S6 kinase 1 (P < 0.01) phosphorylation in mammary glands as compared with the LP and SP diets. The results of the present study suggested that several circulating AAs mediated the effects of dietary protein supply on concentrations of IGF-I, GH, and PRL, which in turn altered the metabolism status in peripheral tissues including the lactating mammary glands.     

Dietary protein concentration affects intestinal microbiota of adult cats: a study using DGGE and qPCR to evaluate differences in microbial populations in the feline gastrointestinal tract

The objective of this study was to identify qualitative and quantitative differences in microbial populations of adult cats fed diets containing different protein concentrations. Following a 4 week baseline period, eight healthy adult domestic short‐hair queens (>1‐year‐old) were randomly allotted to a moderate‐protein (MP; n = 4) or high‐protein (HP; n = 4) diet for 8 weeks. Fresh faecal samples were collected after baseline and 8 weeks on treatment and stored at ?80 °C. Following DNA extraction, samples were analyzed using denaturing gradient gel electrophoresis to distinguish qualitative changes between diets. Quantitative polymerase chain reaction was used to measure E. coli, Bifidobacterium, Clostridium perfringens, and Lactobacillus populations. Compared to baseline, cats fed MP had a bacterial similarity index of 66.7% as opposed to 40.6% similarity for those fed HP, exhibiting marked changes in intestinal bacteria of cats fed HP. Bifidobacterium populations were greater (p < 0.05) in cats fed MP versus HP (9.44 vs. 5.63 CFU/g). Clostridium perfringens populations were greater (p < 0.05) in cats fed HP than MP (12.39 vs. 10.83 CFU/g). In this experiment, a high‐protein diet resulted in a dramatic shift in microbial populations. Decreased Bifidobacterium population in cats fed HP may justify prebiotic supplementation for such diets.     

Effects of limited and excess protein intakes of pregnant gilts on carcass quality and cellular properties of skeletal muscle and subcutaneous adipose tissue in fattening pigs

The aim of this study was to investigate whether dietary protein intake of gilts during gestation below (50%) or above (250%) recommendations affects body composition, carcass and meat quality, and properties of skeletal muscle and subcutaneous adipose tissue (SCAT) in offspring at d 83 and 188 of age. German Landrace gilts were fed isoenergetic gestation diets (~13.7 MJ of ME/kg) containing a low (LP, 6.5%; n = 18), an adequate (AP, 12.1%; n = 20), or a high (HP, 30%; n = 16) protein content from mating until farrowing. Within 48 h of birth, offspring were cross-fostered to sows fed a standard diet. On d 83 of age, no effects of the LP diet on BW and body composition were detected, whereas HP pigs showed a slight growth delay (P = 0.06) associated with increased relative weights of small intestine (P < 0.01) and brain (P = 0.08), and reduced relative thymus weight (P < 0.01). On d 188 of age, BW was not different among the dietary groups. However, the carcass of LP pigs contained less (P = 0.01) lean and more (P = 0.07) fat compared with AP and HP pigs, which was only pronounced in pigs originating from large litters (P < 0.05). Like skeletal muscles (P = 0.06), the heart muscle weighed less (P = 0.02) in LP than AP pigs. Compared with AP pigs, LP pigs exhibited a fewer (P = 0.09) total number of myofibers in semitendinosus muscle plus LM both at d 83 and 188 of age, whereas total muscular DNA was less (P = 0.02) at d 188 only. The mRNA abundance of IGF2 measured on d 188 was reduced in SCAT (P = 0.03) and LM (P = 0.07) of LP compared with AP pigs. No changes in muscular fiber type frequency, capillary density, or creatine kinase activity, as well as SCAT adipocyte size and number, were observed at either stages of age. Meat quality characteristics remained unchanged at d 83, whereas Warner-Bratzler shear force value in LM was decreased (P = 0.03) in LP compared with AP pigs on d 188 of age. The results suggest that the maternal LP diet impairs prenatal myofiber formation, reduces the potential of postnatal lean growth related to reduced IGF2 mRNA expression and myonuclear accumulation, and consequently changes carcass quality toward reduced lean proportion and improved tenderness at market weight. In contrast, except for a slight transient growth delay, excess dietary protein during gestation seems to have little effect on the fetal programming of postnatal muscle and adipose tissue phenotype of the progeny.     

Influence of a high-protein diet on energy balance in obese cats allowed ad libitum access to food

The influence of a high-protein [HP, 47% of metabolizable energy (ME)] diet on energy balance was evaluated in obese cats allowed ad libitum access to food. Energy intake, body weight, body composition, energy expenditure, and concentrations of hormones and metabolites associated with carbohydrate and lipid metabolism (glucose, insulin, free fatty acids, triglycerides and leptin) were measured in cats after consuming either a moderate protein (MP, 27% of ME) or HP diet for 4 months. Indirect respiration calorimetry showed that resting and total energy expenditure (kJ/day) adjusted for either body weight or lean body mass was increased in cats consuming the HP in relation to MP diets. However, voluntary energy intake also was increased in the HP treatment and, thus, there was no difference in body weight between animals consuming the two diets. Body composition measurements using deuterium oxide dilution showed that dietary protein content did not alter amounts of either lean body mass or fat mass. No significant differences (p > 0.05) were observed between the two treatment groups for blood glucose, free fatty acid or leptin concentrations, although there was a trend (p = 0.054) towards an increase of serum insulin concentrations in the cats eating the HP diet. This study showed that short-term ad libitum feeding of an HP diet did not reduce food intake or promote weight loss in obese cats. However, energy expenditure was increased in the HP diet group and it is possible that this effect of HP might help promote weight loss when energy intake is restricted.     

The feeding of ad libitum dietary protein to organic growing-finishing pigs

The effects of three dietary protein levels on growth, meat, and carcass traits were studied in organic pigs fed a three-phase diet. Assuming lysine was the first limiting amino acid, feeds were formulated to ileal digestible (ID) lysine content, with the ID lysine:crude protein ratio set at a constant of 4%. Feeds were also formulated to an isocaloric rate (net energy: 9.4 MJ/kg during the first feeding phase, 9.25 MJ/kg during the second feeding phase and 9.1 MJ/kg during the finisher phase), with a high (HP), a medium (MP) or a low (LP) protein content ranging from 20% to 14% crude protein (CP). ID lysine content of the LP and MP feed was, respectively, 80% and 90% of the ID lysine content of the HP feed. The nutrient formulation of the HP feed was similar to nutrient levels commonly used in conventional Belgian pig farming. From 20 to 40 kg liveweight, the pigs showed better feed conversion ratios, with an increasing dietary protein concentration (r(2)=0.84). This effect was not observed in the second and third phases, although a significant effect of protein concentration on voluntary feed intake in the second phase did occur (P=0.018), probably as a compensation for the lower protein concentration in the LP diet. Analysis of the carcasses showed a lower meat percentage with lower protein concentration (P<0.05), whereas influences on meat quality were limited. It was concluded that whereas during the first phase of growth, higher protein concentration leads to better performance, from the second phase onwards (45 kg), at least with isocaloric diets, a decrease in protein content (corresponding to a 10% reduction in dietary ID lysine levels compared to conventional pig fattening) may be used in organic growing-finishing pig nutrition.     

Effects of high‐fat and high‐carbohydrate diets on fat and carbohydrate oxidation and plasma metabolites in healthy cats

High‐fat (HF) or high‐carbohydrate (HC) diets (30% fat, 18.9% carbohydrate; HF and 10% fat, 46.3% carbohydrate; HC) and lengths of adaptation were investigated in cats (Felis catus; 10 ± 2 months, 3.6 ± 0.3 kg). Cats randomly received each treatment for 14 days in a crossover design with a 14‐day washout period between each diet. Three 22‐h indirect calorimetry studies were conducted after acute (day 0), semichronic (day 4) and chronic (day 13) dietary exposure. Blood samples were collected after a 24‐h fast on days 1, 5 and 14. When cats consumed the HC and HF diet, oxidation of the restricted nutrient exceeded intake while oxidation of the nutrient in excess matched intake. Mean max energy expenditure (EE) of cats consuming the HF and HC diet were 107 and 102 kcal/kg^0.67/day and occurred at a mean of 4 and 12 h post‐feeding respectively. Maximal fat (0.90 g/h) and carbohydrate (carbohydrate; 1.42 g/h) oxidation were attained at 26 min and 10.4 h post‐feeding respectively. The changes observed in macronutrient oxidation and EE suggest that cats adapt whole‐body nutrient metabolism in response to changes in dietary macronutrient content, but may require longer than 14 day to adapt to a macronutrient that is present at a lower concentration in the diet.     

Interactions between mild nutrient imbalance and taste preferences in young ruminants

Thirty-two crossbred lambs (BW = 31.2 ± 4.7 kg; 16 females, 16 males) housed in individual pens were used to investigate the relationship between nutrient supply and taste preferences in ruminants. Experiment 1 determined whether an imbalanced CP supply would alter preferences for feeds containing flavors designed to elicit either umami (U) or a mixture (1/3:1/3:1/3) of umami, sweet, and bitter (M) tastes. Lambs were randomly allocated to either a low (LP; 10.9% CP) or a high (HP; 20.4% CP) CP diet for 21 d. Afterward, lambs were presented during 21 d with a choice of the same LP or HP diet unflavored (LPC or HPC, respectively) or flavored (0.1% as fed) with U (LPU or HPU, respectively) or M (LPM or HPM). Experiment 2 determined the influence of CP status on preference for dietary CP, bitter taste, and sweet taste elicited by sucrose or a noncaloric sweetener. In test 1, sixteen lambs previously fed LP or HP for 42 d in Exp. 1 could choose between the HP and LP diets. In test 2, the remaining 16 lambs from Exp. 1 were offered a choice between unflavored LP or HP diets or the same diets flavored (0.066% as fed) with a bitter flavor. In test 3, the 16 lambs from test 1 were offered a choice between an unflavored diet (LP or HP) and the same diet flavored with sucrose (0.2%) or a noncaloric sweetener (0.066%). In Exp. 1, when offered a choice, all lambs showed a preference (P < 0.05) for the unflavored diet except for LP lambs, who clearly preferred (P < 0.05) LPU (72% of total DMI) over LPC. However, preference for LPU progressively decreased (P < 0.05) as time of exposure to the choice increased. In Exp. 2 (test 1), lambs previously fed LP progressively increased (P < 0.05) total DMI when presented with LP and HP, whereas consumption was constant for lambs previously fed HP and offered a choice of LP and HP diets. At the onset of test 2, lambs fed LP progressively reduced (P < 0.05) preference for the bitter flavor from 53 to 34%. In test 3, lambs previously fed LP diets consumed less (P < 0.05) sweetener- than sucrose-supplemented diet, whereas lambs previously offered HP diets consumed more sweetener- than sucrose-supplemented diet. In summary, protein-restricted lambs were able to differentiate and increase consumption of U-flavored feeds. However, this increase disappeared over time. These results indicate that lambs are able to sense dietary CP content and modulate short-term consumption of flavored feeds based on their nutrient requirements.     

Effects of diets with different protein and DL-methionine levels on the growth performance and N-balance of growing minks

This study was performed to evaluate the effects of diets with different protein and dl-methionine (Met) levels on nitrogen (N) retention, nutrient digestibility, growth performance, and some blood parameters in growing minks. Eighty healthy male minks were selected and randomly divided into five groups with different types of diet. The dietary protein levels, expressed as percentage of dry matter (DM), were 36% (HP) and 28% (LP), corresponding to average 363g and 295g protein/kg DM, respectively. LP was supplemented with Met (0.3%, 0.6% and 0.9% DM); the codes were LP+M1, LP+M2 and LP+M3, respectively. From July to middle of September, the average daily gain and feed: gain ratio (F/G) of the minks that received the diet with 0.6% Met added to the low protein diet was better than feeding HP and other groups. Fecal N and Urinary N of group LP+M2 were the lowest one, in contrast, the daily retention of N was the highest one. Digestibility of DM and CP were not affected by different diets, but digestibility of fat declined with dietary protein level decreasing. Serum urea nitrogen (SUN) was affected by different protein and Met levels. Considering all factors the best performance could be observed offering LP+M2, the prime level of Met was 13.87 g/kg DM in dietary, and 258.5 g digestible protein kg(-1) DM was enough for mink in growing period. Furthermore, addition of Met in low protein diets for minks would be beneficial in terms of reduced feed expenses and lower nitrogen emissions to the environment.     

Effects of Dietary Protein Levels on Urinary Sediments of Early Weaned Tibetan Lambs

This research was aimed to study the effects of dietary protein levels on urinary sediments of early weaned Tibetan lambs. Ninety healthy two months old male Tibetan lambs with weaning weight (20.80±2.75) kg were chosen and randomly divided into three groups with thirty replicates per group and one lamb per replicate. The lambs in three groups were fed based diets with 10.8%(LP group), 12.0% (MP group) and 13.2%(HP group) crude protein, respectively,and the trial period lasted for 127 days. The results showed that:In HP group,the bladder and urethra of three lambs were damaged,and one lamb had bladder calculi,while there was no lamb had the above phenomenon in LP and MP groups,which meant that the relative low protein levels could reduce the incidence of urinary system diseases,so as to improve the health of lambs.The white blood cells and conductivity in LP group were volatile and there was no cast.The indexes of urine sediments in HP group were volatile,and the counts of white cell,red cell,crystals and yeast-like fungi were increasing with the increase of days.While the urine sediments in MP group were slight oscillation within the normal range,and there was no cast.Under the experimental condition,the dietary protein levels did had an impact on the urinary sediments in early weaned Tibetan lambs. When the dietary protein levels was 12.0%,the urinary sediments were best,and the urinary tissues were more complete,and conducive to production.     

日粮蛋白质水平对早期断奶藏羔羊尿沉渣的影响

试验旨在研究不同蛋白质水平日粮对早期断奶藏羔羊尿沉渣指标的影响。采用单因子随机试验设计,选取2月龄断奶、体重（20.80±2.75） kg的健康藏公羔羊90只,随机分为3组,每组30个重复,每个重复1只羊,分别饲喂蛋白质水平为10.8%（LP组）、12.0%（MP组）和13.2%（HP组）的日粮,试验期127 d。结果显示,HP组中有3只羔羊膀胱、输尿管组织出现损伤,且1只有膀胱结石,LP、MP组羔羊均未出现尿路疾病致死症状,表明较低的蛋白质水平可以降低后期泌尿系统疾病的发病率,从而改善羔羊的健康。LP组白细胞和电导率数量波动较大,无管型,HP组尿沉渣指标均波动较大,白细胞,红细胞,结晶,类酵母菌数量均呈上升趋势,MP组尿沉渣波动较小,均在正常范围内,且无管型。在本试验条件下,日粮蛋白质水平对早期断奶藏羔羊的尿沉渣指标有显著影响,且日粮蛋白质水平为12.0%时,尿沉渣指标最优,死亡率最低,泌尿组织较完整,机体最健康,有利于生产。     

Energy and protein metabolism in pregnant sows fed two levels of dietary protein

The present study was performed to quantify the energy and nutrient metabolism of pregnant sows fed high (HP) or low (LP) dietary protein [18.3 vs. 13.5% of dry matter (DM)]. A total of nine sows (four on HP and five on LP diet) were subjected to balance and respiration trials four times during their second pregnancy (approximately on days 30, 61, 80 and 104 of gestation). The digestibility of protein (83.0 vs. 79.9) (p < 0.01) and energy (84.9 vs. 83.7%) (p < 0.05) was higher for the HP diet. Daily intake of metabolizable energy (ME) and retained energy (RE) were similar for the two groups, with an average of 28.37 MJ ME and 3.94 MJ RE, respectively. Heat production (HE) measured according to the respiratory quotient (RQ) and carbon-nitrogen (CN) method was similar (464 vs. 454 kJ/kg 0.75/day, respectively). Sows fed HP retained more energy in protein (3.33 vs. 2.00 MJ/day) (p < 0.001) and tended to retain less energy in fat (1.59 vs. 2.50 MJ/day) than LP sows. Retained nitrogen (N) (22.3 vs. 13.4 g/day) (p < 0.001) and utilization of N (retained/digested) (45.2 vs. 38.1%) was higher for HP sows compared with LP sows. In late pregnancy, retained N, retained fat, HE and oxidation of carbohydrates increased, while oxidation of fat was reduced to zero. In conclusion, both diets provided adequate N for retention in maternal tissue and conception products. In spite of the lower utilization of N in LP sows, the N excretion was depressed by 5.6 g/day compared with HP sows, because of the lower N intake.     

Effect of dietary protein content on episodic growth hormone secretion and on heat production of male broiler chickens.

1. The effect of the crude protein content (200 and 150 g/kg) of isoenergetic diets on episodic growth hormone (GH) release and on heat production was investigated in male broiler chickens. 2. Decreasing the crude protein content of isoenergetic diets from 200 g/kg (HP diet) to 150 g/kg (LP diet) resulted in depressed body weight gain, impaired food conversion efficiency and increased abdominal fat deposition. 3. The pattern of growth hormone secretion was markedly affected by dietary treatment. Broiler chickens fed on the LP diet had higher overall mean, amplitude, baseline and peak frequency than the HP chickens. 4. The LP chickens produced more heat per unit of metabolic body weight than the HP chickens. 5. The hypothesis relating the pattern of GH secretion to protein conversion efficiency was corroborated.     

Rate of metabolic decarboxylation of leucine as assessed by a l[1-(13)C(1)]leucine breath test combined with indirect calorimetry of broiler chickens fed isocaloric diets with different protein:fat ratio

Research has shown that broiler chickens reared on a low-protein diet have a more efficient protein digestion. However, information on the fate of absorbed amino acids in relation to the dietary crude protein level in poultry is sparse. Therefore, this study aimed at developing a methodology for a 1-(13)C(1)-leucine breath test combined with indirect calorimetry, and to apply this technique using broiler diets known to induce differences in protein retention. From 14 days of age onwards, broiler chickens were reared on one of two isocaloric diets with substitutions between fat and protein [low-protein (LP) vs. high-protein (HP) diet: 130.4 vs. 269 g protein/kg; and 101.8 vs. 27.9 g fat/kg]. Every 4 or 5 days, three chickens per diet were placed in the respiratory cells for 48 h. The broilers were intubated with 40 mg 1-(13)C(1)-leucine/kg body weight, followed by breath sampling for 4 h at 15-min intervals and mass spectrometric analysis of the (13)C:(12)C ratio in the samples. The CO(2) level in the respiratory cell air was monitored and excreta samples were collected. The methodology to study l[1-(13)C(1)]leucine decarboxyation in chickens using a breath test combined with indirect calorimetry was accomplished. Results of the nitrogen balance test indicated that the LP broilers had an improved dietary protein retention compared with the HP animals. Moreover, LP chickens decarboxylated a significantly lower percentage of l[1-(13)C(1)]leucine, demonstrating several 'protein- or amino acid-sparing' mechanisms in animals reared on a diet with lower protein level, both at the digestive and at the postabsorptive level.     

Seasonal Changes in Testicular Cell Morphology in Domestic Male Cats (Felis catus)

The aim of this study was to asses the variation in the morphology of the seminal epithelium in relation to natural photoperiod in male cats. Tom cats (n = 240) were castrated every other week throughout the year. Each testis was fixed in Bouin's solution and cut into sections. The percentage of tubules with round spermatids (RS), elongated spermatids (ES), tailed spermatids (TS), mature spermatids (MS) and the number of Sertoli cells (SC) and Leydig cells (LC) were recorded in each sample. Testicles from males during short days (SHD) had a higher percentage of tubules with RS and ES compared to testicles from males during long days (LHD, 31.3 ± 0.6 vs 2.1 ± 0.6%, p < 0.001; 30.9 ± 0.7 vs 11.0 ± 0.7%, p < 0.001). Conversely, testicles from males during SHD had a lower percentage of tubules with TS and MS compared to testicles from males during LHD (24.5 ± 0.8 vs 29.7 ± 0.8%, p < 0.01; 13.1 ± 1.2 vs 57.0 ± 1.2%, p < 0.01). Furthermore, testicles from males during SHD had a higher number of SC and lower number of LC compared to testicles from males during LHD (11.4 ± 0.1 vs 8.0 ± 0.1%, p < 0.01; 19.2 ± 1.0 vs 38.0 ± 1.0%, p < 0.01). In conclusion, there are seasonal changes in testis cell morphology in the tom which may be related to seasonal sperm production.     

Dietary protein concentration correlates in a complex way with glucose metabolism and growth performance in pregnant rats

We studied the influence of dietary protein concentration (PC) on the adaptation mechanism of maternal glucose metabolism to gestation, and on maternal body weight (BW) gain using pregnant rats fed 4% (low protein, LP), 10% (medium protein, MP) or 20% (high protein, HP) dietary protein concentration. Feed (FI), energy (EI) and protein (PI) intakes were recorded. Plasma glucose, insulin and GH were determined, and insulin:glucose (insulin resistance) and insulin:GH ratios computed. Correlation and regression analyses were used to determine the physiological relationships between metabolic and ponderal variables. MP dams with greater FI and EI (12%), and lower PI (44%) than HP dams showed similar maternal and fetal growth performance because of the maintained energy efficiency (EE). LP dams, with similar FI and EI, and lower PI (81%) than HP dams, failed to catch up due to the low EE. PC exerted a non-linear influence on BW gain, insulin and GH, through EI and EE modifications. The EI linearly influenced hormone concentrations with the maximum and minimum hormone response in MP and LP dams, respectively. Insulin resistance increased as PC decreased, whereas the GH lipolytic effect appeared to predominate over insulin action. Circulating hormones and metabolites affected nutrient partitioning between dam and fetus, with the result that the competing demands for materno-fetal growth of HP and MP dams, but not the LP dams, were satisfied. A deeper knowledge of the nature of the materno-fetal energy relationships will enhance the manipulation of the growth performance of the fetus in several animal species.