Effect Of Feed Deprivation Research Articles

Effects of Feed Deprivation on the Biochemical Responses of Pangasianodon hypophthalmus

Effects of Feed Deprivation on the Biochemical Responses of Pangasianodon hypophthalmus

Effect of feed deprivation on immune-haematological responses and resistance of Labeo rohita (Hamilton, 1822) to Aeromonas hydrophila infection

Effect of feed deprivation on immune-haematological responses and resistance of Labeo rohita (Hamilton, 1822) to Aeromonas hydrophila infection

Weaning-associated feed deprivation stress causes microbiota disruptions in a novel mucin-containing in vitro model of the piglet colon (MPigut-IVM)

BackgroundRisk factors for the etiology of post-weaning diarrhea, a major problem in swine industry associated with enormous economic losses, remain to be fully elucidated. In concordance with the ethical concerns raised by animal experiments, we developed a new in vitro model of the weaning piglet colon (MPigut-IVM) including a mucin bead compartment to reproduce the mucus surface from the gut to which gut microbes can adhere.ResultsOur results indicated that the MPigut-IVM is able to establish a representative piglet archaeal and bacterial colon microbiota in terms of taxonomic composition and function. The MPigut-IVM was consequently used to investigate the potential effects of feed deprivation, a common consequence of weaning in piglets, on the microbiota. The lack of nutrients in the MPigut-IVM led to an increased abundance of Prevotellaceae and Escherichia-Shigella and a decrease in Bacteroidiaceae and confirms previous in vivo findings. On top of a strong increase in redox potential, the feed deprivation stress induced modifications of microbial metabolite production such as a decrease in acetate and an increase in proportional valerate, isovalerate and isobutyrate production.ConclusionsThe MPigut-IVM is able to simulate luminal and mucosal piglet microbiota and represent an innovative tool for comparative studies to investigate the impact of weaning stressors on piglet microbiota. Besides, weaning-associated feed deprivation in piglets provokes disruptions of MPigut-IVM microbiota composition and functionality and could be implicated in the onset of post-weaning dysbiosis in piglets.

Effects of feed deprivation on physical and blood parameters of horses.

The objective of this study was to evaluate the effect of feed restriction on some physical and blood parameters in horses kept outdoors under natural conditions. Twenty horses were deprived of food for 48 h. They were closely monitored and examined, and blood samples were taken at the beginning (0) of the experiment and 6, 12, 18, 24, 30, 36, 42 and 48 hours afterward. During the experimental period, the control group (12 animals) had free access to water and hay, while the restricted group had free access to water only. Data were submitted to two-way analysis of variance with repeated measures, and statistical significance was P ≤ 0.05. The horses tolerated feed restriction without complications. Feed restriction had no effect on body mass and body condition score, heart rate, respiratory rate, capillary filling time and body temperature. However, feed restriction decreased the intensity of gastrointestinal sounds (P<0.05) compared to the control horses. Feed restriction did not cause any changes in erythrocyte variables and gamma glutamyl transferase, creatinine, total protein, and albumin concentrations. During fasting, there was a reduction in the leukocyte response (P<0.05). Feed restriction significantly raised the levels of blood urea nitrogen (24 to 48 hours), aspartate aminotransferase (36 to 48 hours) and total cholesterol (42 to 48 hours). During 48 hours of fasting, there was a continuous increase in triglyceride concentration. Feed restriction for 48 h had a marked effect on the intensity of gastrointestinal sounds and was responsible for important metabolic changes in the healthy horses of our sample.

Effects of feed restriction on growth performance, lipid mobilization, and gene expression in rose spotted snapper (Lutjanus guttatus)

The effects of feed deprivation were evaluated for 1week and 2weeks in Lutjanus guttatus juveniles. A significant reduction in body mass was observed in both feed deprivation schemes, as well as in hepatosomatic, viscerosomatic and mesenteric fat indexes. The composition of fasted fish was characterized by a decrease in lipid content; the liver displayed an intense reduction of lipid reserves in both fasted groups, and increased expression of the lysosomal acid lipase. 1week after re-feeding, both experimental groups showed an increase in specific growth rate, feed intake and feed conversion ratio. A recovery in hepatic lipid reserves was observed, and the expression of the lysosomal acid lipase decreased, although lipid content in both groups was still significantly lower than in control groups. Hepatic expression of the growth hormone receptor decreased after fasting, and remained low even after the fish were fed, whereas the expression of insulin-like growth factor 1 and 2 increased after fasting and decreased in both groups when fish were fed again. Altogether, these results showed a partial compensatory growth response in L. guttatus juveniles after fasting, with enhanced growth rates and improved feed efficiency. Fish used stored lipid reserves as the main energy source, and the expression of growth-related and lipid mobilization marker genes in the liver showed similar patterns in both fasting schemes. Based on the results, we suggest as much as 1-week fasting intervals during grow-out programmes to reduce visceral fat and increase growth rate in this species.

Effect of feed deprivation on compensatory growth in juvenile rock bream Oplegnathus fasciatus

A feed-deprivation study was conducted for 9 weeks with four feeding regimes, estimating compensatory growth and proximate composition of rock bream Oplegnathus fasciatus (56.0 ± 0.9 g). Feeding regimes included continuous feeding (control), feed-deprivation for 1 week (S1) in week 3, for 2 weeks (S2, weeks 2–3), and for 3 weeks (S3, weeks 1–3). Following 3 weeks, fish were on a continuous feeding regime for the remaining period. Complete compensation was achieved in S1 and S2 after resuming feeding for 3 weeks and 6 weeks. Although specific growth rate, feeding rate and feed efficiency in S3 were higher than in the control during the feeding resumption period, S3 fish did not catch up the body weight of control fish by the end of the experiment. At the end of the feed-deprivation period, the ratio of lipid to lean body mass and the levels of protein, lipid, and energy in S1, S2 and S3 were lower than those in the control. After feeding resumption for 6 weeks, protein and lipid contents in S3 were significantly (P < 0.05) lower than those in the control. Rock bream with single-phase feed-deprivation for 1–2 weeks could exhibit full compensatory growth after feeding resumption for 3–6 weeks under our experimental conditions.

Effects of long-term feed deprivation on body weight loss, muscle composition, plasma metabolites, and intermediate metabolism of meagre (Argyrosomus regius) under different water temperatures.

The effect of feed deprivation at four water temperatures (17, 20, 23, 26°C) was investigated in meagre (Argyrosomus regius) of initial mean weight ± SD, 116.16 ± 4.74g, in triplicate groups. Fish were deprived of feed for a period of 60days and sampled on days 0, 14, 41, and 60, during which body weight, specific growth rate, somatic indices, muscle proximate composition, plasma metabolite levels (total lipids, proteins, cholesterol, triglycerides, glucose), and liver and muscle enzymatic activities [L-lactate dehydrogenase (L-LDH), citrate synthase (CS), malate dehydrogenase (MDH)] were evaluated. Long-term feed deprivation resulted in a significant decrease in body weight, condition factor (CF), hepatosomatic index (HSI), muscle lipids, and plasma metabolites (all except proteins) and increase in muscle moisture. Plasma glucose concentration decreased with time and became significantly lower at 41 and 60days. Glucose concentration and weight loss expressed a different response in the short term (14days) than in the long term (14 and 60days) of feed deprivation, suggesting a change in glucose metabolic profile. After 60days of feed deprivation, there was an increase in the L-LDH activity in the liver at all temperature levels, which reflects a rising glycolytic potential by activating the carbohydrate metabolism and an ATP-dependent demand. MDH activity increased in the liver and muscle, except at 17°C in the muscle, which indicates aerobic glycolysis and lipolysis. CS activity in the liver increased after the 60days, whereas that in the muscle decreased, indicating the muscle is less dependent on aerobic oxidation for energy reserves.

Effect of feed deprivation on selected parameters of lipid mobilisation and hepatic function in healthy Akhal Teke horses

Gastrointestinal and other systemic diseases of Equidae are often characterised by partial or complete inappetence. The catabolic processes may lead to lipid mobilisation and other metabolic disturbances. Evidence from earlier studies has revealed that during feed deprivation/inappetence, the conjugation of bilirubin is reduced causing a substantial rise of the total bilirubin and its unconjugated fraction. We hypothesised that during feed deprivation, the serum concentration of free fatty acids (FFA), triglycerides (TG), blood urea nitrogen (BUN), total bilirubin (tBIL), total bile acids (tBA) and activity of GGT and GLDH increases, while the concentration of insulin and direct bilirubin (dBIL) decreases. Observational experiment. Eleven horses were feed deprived for 96 h. Animals were closely monitored while blood samples were taken at the beginning, and then at 72, 84 and 96 h later. Variables of interest included serum FFA, TG, insulin, GGT, GLDH, total and direct BIL (t&dBIL), tBA and BUN. The data were analysed by descriptive statistics, paired t-test and one-way repeated measures ANOVA with post-hoc HSD test, and P≤0.05 was considered significant. Horses tolerated feed restriction without complications. During this time, the concentration of TG, FFA, BUN, dBIL and insulin significantly increased (P≤0.05), as well as the activity of serum GGT, while the concentration of tBIL, tBA and the activity of GLDH did not change significantly (P>0.05). Sample size, lack of serum volatile fatty acid, cortisol and blood glucose measurements may have limited the value of the study. Healthy Akhal Teke horses did not develop a catabolic crisis following 4 days of feed restriction and hyperlipaemia did not occur. Total BIL and tBA did not increase, thus were not useful indicators of inappetence in this group of horses.

Effects of feed deprivation on the AMPK signaling pathway in skeletal muscle of broiler chickens.

The 5'-adenosine monophosphate-activated protein kinase (AMPK) plays a key role in rapid metabolic adaptations to maintain energy homeostasis in poultry. It remains unclear if AMPK is involved in muscular energy metabolism in broiler chickens. Hence, in the present study, seven-day-old male broilers were equally divided into three groups: fed ad libitum (control); feed-deprived for 24h (S24); feed-deprived for 24h and then refed for 24h (S24R24). Compared to the control group, the plasma levels of glucose, insulin, T3 and triglycerides in the S24 group were significantly lower (P<0.05), whereas the uric acid levels were significantly higher (P<0.01). Except for glucose, refeeding for 24h reversed the fasting-induced alterations in plasma metabolite. Fasting decreased the liver kinase B1 (LKB1), AMPK alpha 2 subunit (AMPKα2), and fatty acid synthase (FAS) mRNA levels (P<0.05) in M. pectoralis major (PM). Feed deprivation did not affect the phosphorylated AKT, mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70S6K) in PM (P>0.05), but upregulated carnitine palmitoyltransferase 1 (CPT1) gene expression and increased phosphorylated LKB1 (0.05<P<0.1) and AMPKα (P<0.05) levels. AMPKα2, FAS, and CPT1 mRNA levels and the protein levels of phosphorylated AMPK and LKB1 of the PM muscle returned to control group levels after 24h refeeding. In M. biceps femoris (BF), the AMPKα2 and FAS mRNA levels were decreased by fasting compared to control (P<0.05), whereas CPT1 mRNA and phosphorylated LKB1 and AMPK protein levels were increased. Refeeding for 24h reversed the changes in AMPKα2 and CPT1 gene expression and phosphorylated AMPKα2 subunit. Fasting did not affect the AKT, mTOR and p70S6K in both PM and BF muscles (P>0.05). However, refeeding after 24h of fasting increased the phosphorylated mTOR level in BF muscle which was in parallel with increased plasma insulin concentration. It was likely that increased phospho-mTOR level in the BF muscle was due to the higher sensitivity of BF to insulin. Together, the results suggested that the AMPK signaling pathway might be involved in the energy metabolism alterations in the skeletal muscles of broiler chickens and was also dependent upon the muscle fiber type. Furthermore, the regulatory effects of AMPK on energy metabolism in muscles of broiler chickens might be mediated by the AMPK/FAS pathway.

Feeding strategies and energy to protein ratio on tambaqui performance and physiology

The objective of this work was to evaluate the effect of feed deprivation and refeeding with diets containing different energy to protein ratios (E/P) on the performance and physiology of juvenile tambaqui (Colossoma macropomum). A 4x2 factorial arrangement with three replicates was used, with four E/P ratios (11.5, 10.5, 9.5, and 8.5 kcal g-1 digestible energy per protein) and two feeding regimens (with and without deprivation), during 60 days. Fish from the food-deprived group were fasted for 14 days and refed from the fifteenth to the sixtieth day, whereas the remaining fish were fed for 60 days. At the end of the experimental period, weight of fish subjected to food deprivation was lower than that of those continuously fed; however, this condition did not influence the physiological parameters analyzed. Tambaqui fed 11.5 kcal g-1 achieved lower final weight than those fed with the other diets, in both regimens. Among the physiological parameters, only plasma protein presented significant increase in fish fed 8.5 kcal g-1, in both feeding regimens, probably due to the higher dietary protein concentration. These results indicate that fish show a partial compensatory growth, and that 10.5 kcal g-1 can be recommended for the diet of juvenile tambaqui.

Effect of feed deprivation and lairage time on carcass and meat quality traits on pigs under minimal stressful conditions

Fasting pigs at the farm prior to transport and keeping pigs in lairage before slaughter can affect carcass, gastrointestinal tract content and meat quality. The aim of the present study was to determine the effect of the on-farm fasting periods and lairage on the killing-out, carcass and meat quality. Seventy-two pigs were submitted to a 2×2 experimental design, with two on-farm fasting periods (0 or 12h) and two lairage times (0 or 12h) while handling was performed under minimal stressful ante mortem conditions. Feed intake was monitored individually, and carcass and meat quality traits were studied. On-farm fasting time increased life body weight losses during the on-farm fast period (P<0.001) and cold killing-out (P=0.01). On-farm fasting time also tended to increase skin lesions (P=0.082) and pH measured at 45min in the Semimembranosus muscle (P=0.0753). Lairage also increased body weight losses (P<0.001) and killing-out (P=0.003), and did not affect any of the meat quality traits. The following meat quality classes were also defined: (i) pale, soft and exudative, (ii) red, soft and exudative, (iii) pale, firm and exudative, (iv) red, firm and non-exudative, and (v) dark firm and dry. Their incidence was studied: no incidence of dark, firm and dry pork was observed, and loins from pigs fasted up to 12h were mainly classified as red, soft and exudative. In the present study, long feed deprivation (24–26h) did not negatively affect carcass traits and reduced the incidence of exudative meat without increasing the occurrence of dark firm and dry pork.

Effects of plane of nutrition and feed deprivation on insulin responses in dairy cattle during late gestation

Nonlactating Holstein cows (n=12) in late pregnancy were used to determine effects of plane of nutrition followed by feed deprivation on metabolic responses to insulin. Beginning 48 d before expected parturition, cows were fed to either a high plane (HP) or a low plane (LP) of nutrition (162 and 90% of calculated energy requirements, respectively). Cows were subjected to an intravenous glucose tolerance test [GTT; 0.25g of dextrose/kg of body weight (BW)] on d 14 of treatment and a hyperinsulinemic-euglycemic clamp (HEC; 1μg/kg of BW/h) on d 15. Following 24h of feed removal, cows were subjected to a second GTT on d 17 and a second HEC on d 18 after 48h of feed removal. During the feeding period, plasma nonesterified fatty acid (NEFA) concentrations were higher for cows fed the LP diet compared with those fed the HP diet (163.6 vs. 73.1μEq/L), whereas plasma insulin was higher for cows fed the HP diet during the feeding period (11.1 vs. 5.2μIU/mL). Glucose areas under the curve during both GTT were higher for cows fed the LP diet than for those fed the HP diet (4,213 vs. 3,750mg/dL × 60min) and was higher during the GTT in the feed-deprived state (4,878 vs. 3,085mg/dL × 60min) than in the GTT during the fed state, suggesting slower clearance of glucose during negative energy balance either pre-or post-feed deprivation. This corresponded with a higher dextrose infusion rate during the fed-state HEC than during the feed-deprived-state HEC (203.3 vs. 90.1 mL/h). Plasma NEFA decreased at a faster rate following GTT during feed deprivation compared with that during the fed state (8.7 vs. 2.9%/min). Suppression of NEFA was highest for cows fed the HP diet during the GTT conducted during feed deprivation, and lowest for cows fed the HP diet during the fed-state GTT (68.6 vs. 50.3% decrease from basal). Plasma insulin responses to GTT were affected by feed deprivation such that cows had a much lower insulin response to GTT by 24h after feed removal (995 vs. 3,957μIU/mL × 60min). During the fed-state HEC, circulating concentrations of NEFA were 21% below basal for cows fed the HP diet and 62% below basal for cows fed the LP diet; during feed deprivation, NEFA were 79 and 59% below basal for the HP and LP diets, respectively (diet × HEC). Cows that are fed below energy requirements or are feed deprived have slower clearance of glucose and greater NEFA responses to glucose challenge. Additionally, feed deprivation had a large effect on insulin secretion. Overall, effects of feed deprivation were larger than effects of plane of nutrition.

Effects of feed deprivation on behavioral reactivity and physiological status in Holstein cattle1

The present study evaluated whether feed deprivation can increase reactivity to stressful events, such as those that can occur at slaughter. Therefore, effects of 30 h of feed deprivation on behavior, including reactions to psychological stressors, and physiological status in cattle were determined. Sixteen Holstein cows (Exp. 1) and 32 Holstein heifers (Exp. 2) were either fed (FE) or 30-h feed deprived (FD). Throughout the first day of feed deprivation and during evening feed distribution to control animals, FD heifers and cows were more active than controls (P < 0.05). In Exp. 1, during a feeding test, in response to a sudden air blast arising from the bucket from which the cow was feeding, FD cows showed a longer latency to return to feed (P = 0.0002), spent less time in the bucket air blast zone (P = 0.008) and less time motionless (P = 0.03), and tended to withdraw over a longer distance (P = 0.07) than FE cows. In Exp. 2, during a reactivity test, FD heifers spent more (P = 0.0001) time motionless in response to social isolation than FE heifers. In Exp. 2, one-half of the FE and FD heifers were subjected to an additional physical and psychological stressor just before the reactivity test by driving them for 5 min through a labyrinth. Within heifers subjected to the additional stressor, FD heifers were less accepting of being detained (P = 0.05) and stroked (P = 0.003) by a familiar stockperson in a corner of the test arena. Compared with FE animals, FD heifers and FD cows had greater plasma cortisol concentrations (P < 0.05). Feed-deprived cows also had reduced β-hydroxybutyrate concentrations (P = 0.02) compared with FE cows. Thus, in cattle, FD influenced some of the classical indicators of energy metabolism and exacerbated reactivity to sudden events. In addition, when additional stressors were applied, FD cattle were more reluctant to accept handling. Results indicate that a multifactorial origin of stressors during the slaughter period may synergistically increase psychological stress of cattle.

Effects of feed deprivation on Standardbred horses fed a forage‐only diet and a 50:50 forage‐oats diet

A higher forage allowance to athletic horses might be an alternative to increase health and the gut fluid reservoir. However, more forage might increase bodyweight (bwt) and could therefore be a limitation during competition. To investigate the effect of a forage-only diet (FD) compared to a 50:50 (dry matter basis) forage:oats diet (OD) on bwt, plasma protein concentration and some metabolic plasma parameters during 12 h of feed deprivation. Twelve adult Standardbred horses in training were used. The 2 diets were fed in 2 experimental periods of 3 weeks each in a crossover design. The last day of each period the horses were fasted for 12 h. The horses were weighed and their water intake measured every day during the trial and every hour during the 12 h feed deprivation. During feed deprivation total plasma protein (TPP), insulin, nonesterified fatty acids (NEFA), urea, glucose and acetate concentrations were analysed. Bwt and water intake was higher on FD compared to OD. Bwt loss was higher during feed deprivation on FD compared to OD. TPP was lower before and during the last 8 h of feed deprivation on FD compared to OD. Plasma insulin was lower on FD than on OD at feeding and for 5 h during feed deprivation. Plasma NEFA and urea increased on both diets during feed deprivation. Plasma glucose was not affected by diet or feed deprivation. High energy forage diets could be an alternative to high grain diets for athletic horses. The small increase in bwt on FD diminished with feed deprivation and the low TPP concentration indicate a greater potential to use an internal fluid compartment to maintain plasma volume.

EFEITO DO JEJUM NO INTERVALO ENTRE O NASCIMENTO E O ALOJAMENTO SOBRE O DESEMPENHO DE FRANGOS DE CORTE PROVENIENTES DE MATRIZES DE DIFERENTES IDADES

Este estudo foi conduzido para avaliar o efeito do jejum entre o nascimento e o alojamento sobre o consumo de ração, ganho de peso, conversão alimentar e viabilidade criatória até 42 dias de idade; perda de peso e consumo de ração no período que suceder ao nascimento, em frangos de corte provenientes de matrizes de diferentes idades. Foram utilizados 480 pintainhos de corte, machos, em um delineamento inteiramente casualizado, em esquema fatorial 2 x 3 com os fatores idades de matriz (30 e 60 semanas) e períodos de jejum (0, 24 e 48 horas pós-eclosão). A idade da matriz não influenciou a perda de peso dos pintainhos entre o nascimento e o alojamento, variável esta afetada apenas pelo período de jejum a qual as aves foram submetidas. Pintainhos oriundos de matizes de 60 semanas de idade consumiram maior quantidade de ração nas 72 horas pós-eclosão. A idade da matriz influenciou também o consumo de ração e o ganho de peso aos 7 e 21dias de idade, sendo que pintainhos oriundos de matrizes mais velhas tiveram maior consumo e ganho de peso. No entanto, aos 42 dias, mesmo que as aves tenham sido submetidas a períodos de jejum pós-natal, não houve diferença no desempenho. Pintainhos oriundos de matrizes de 30 semanas tiveram melhor conversão alimentar nesta idade.

The Effect of Feed Deprivation on Tissue Invasion by Salmonella enteritidis

A tissue culture procedure was utilized to compare tissue cell invasion by Salmonella enteritidis from molted and full feed hens. Three identical trials were performed in which 80-wk-old active laying hens were divided into 2 groups of 6 birds each. The molted hen group was subjected to a 14-d feed withdrawal, and the full-fed hen group was administered a standard layer ration. After feed treatment, crop, ileum, cecum, and ovary (small and large yellow follicles removed) were collected, rinsed in PBS, and placed into 50 mL of RPMI medium. The ends of intestine and crop tissues were tied to allow attachment of Salmonella only to the lumen surface. The RPMI medium containing 107 to 108 cfu of novobiocin and nalidixic acid-resistant phage type 13 Salmonella enteritidis was injected into the lumen of the intestine and crop tissues. Additionally, ovaries were incubated in 50 mL of RPMI medium containing 106 to 107 cfu of the Salmonella enteritidis. Tissues were incubated with Salmonella at 37°C for 2 h, after which tissues were placed in 50 mL of fresh RPMI medium containing 500 μg/mL of gentamicin and incubated for 5 h at 37°C to remove any Salmonella that had not penetrated tissues. Tissues were rinsed, stomached in 10 mL of PBS, serially diluted, and plated onto brilliant green agar containing novobiocin and nalidixic acid for Salmonella enumeration. Salmonella invasion of ovaries was reduced in tissues from molted hens in trials 1 and 2 as compared with full-fed controls (>1.2 log reduction) but not in trial 3. Salmonella invasion of ceca from molted hens was numerically increased in trials 1 and 2 and significantly increased in trial 3 as compared with controls (>0.8 log increase). No significant differences in Salmonella invasion were detected for crops and ileum. These data suggest that molting may affect invasion of tissues by Salmonella enteritidis.

Effects of feed deprivation and transport on preslaughter blood metabolites, early postmortem muscle metabolites, and meat quality

In practice, poultry have their feed with drawn several hours before being collected and put on transport to the slaughter plant. With the exhaustion of their internal energy stores, the chickens may lack energy to cope with the conditions to which they are subjected. Meat quality is affected by the energy stored in the muscle at time of slaughter and its rate of decrease postmortem. Of 320 broiler chickens, half were subjected to 5 h feed deprivation whereas the others had access to feed until transport. In both groups, half the chickens were transported for 1.5 h, and the rest were transported within 5 min to the on-site slaughter facility. Twenty chickens were equipped with an ultrafiltration-collection device for monitoring glucose and lactate profiles. After slaughter, liver pH was measured. Stimulation of muscle metabolism was minimized by avoiding plucking. Breast muscle samples were taken at 0, 1, 2, 4, and 6 h and analyzed for pH and metabolite concentrations, and meat quality was measured at 96 h. Although liver glycogen was depleted in feed-deprived chickens, feed deprivation and transport for short periods were not found to affect blood glucose or lactate levels nor glycogen levels in the muscle at slaughter. Muscle carbohydrate metabolism was found to come to a complete halt after 6 h, which was not caused by exhaustion of the glycogen store but by the muscle's ability to generate adenosine triphosphate (ATP) after 4 h. At this time, rigor mortis had set in and deboning could be done without risk of cold shortening.

Effects of feed deprivation and electrical, gas, and captive needle stunning on early postmortem muscle metabolism and subsequent meat quality

The general method for stunning poultry before slaughter is by immersion of a chicken's head into an electrified waterbath. This method results in carcass and meat quality deficiencies. The major problems are hemorrhages and a delay in onset of rigor mortis, which increases the risk of cold shortening with early deboning. In two experiments, this study examines the early postmortem metabolism in the breast muscle and its effect on ultimate meat quality. The first experiment describes the effects of 5 h feed deprivation on the availability of glycogen from the liver and the breast muscle, of waterbath and head-only electrical stunning on pH and metabolite levels up to 6 h in unprocessed muscle, and the consequences on meat quality. The second experiment compares the same measurements after waterbath and head-only electrical stunning, CO2/O2/N2 and Ar/CO2 gases, and captive needle stunning. Metabolic degradation halted after 6 h without processing or after 4 h under conventional conditions after waterbath and CO2/O2/N2 stunning. With other stunning methods, this occurrence is at a faster rate, largely depending on muscle activity. Muscle glycogen does not need to be exhausted for energy generation to cease. If glycogen is a limiting factor, as found with head-only stunning, pH drops too rapidly and affects water-holding capacity and color. Hemorrhage scores were higher with electrical stunning than with other stunning methods. Gas stunning affected color and, to a lesser extent, water-holding capacity. Captive needle stunning scored between gas and electrical stunning on most measurements.

Growth performance, body composition and plasma thyroid hormone status of channel catfish (Ictalurus punctatus) in response to short-term feed deprivation and refeeding

A 6-week feeding trial was conducted to investigate the effects of short-term feed deprivation on inducing compensatory growth and changes in thyroid hormone levels of channel catfish. Feeding treatments consisted of the following four regimes of 2-week duration: satiate feeding (control), no feed for 3 days then feeding to apparent satiation for the next 11 days, no feed for 5 days then feeding to apparent satiation for 9 days, and no feed for 7 days then feeding to apparent satiation for 7 days. These regimes were repeated three times over the 6-week trial in which 25 channel catfish fingerlings, initially averaging 15 g each, were stocked into each of 12, 38-l glass aquaria supplied with supplemental aeration and flow-through water. Depriving fish of feed had a pronounced effect in that fish lost weight in as little as 3 days. Returning the fish to a satiate feeding regime caused a resumption of growth, equal to control growth only in the case of the 3-day deprived treatment, but all periods of feed deprivation failed to induce a period of catch-up growth adequate to compensate for previously lost weight. Feed efficiency also was not improved by the periods of feed deprivation, and restricting feed in excess of 3 days lowered feed efficiency. Fish condition indices were not altered at the termination of the trial. Muscle lipid, muscle protein and liver protein also were not different among feeding regimes. Liver lipid was elevated in fish deprived of feed for more than 3 days every 2 weeks. Plasma thyroxine (T4) and triiodothyronine (T3) were equally depressed by 3 days from the onset of feed deprivation. Both hormones rose significantly within 24 h of realimentation, with the greatest increase observed in animals subjected to the briefest feed deprivation. These results support a role for thyroid hormones in the promotion of growth in channel catfish. Whereas feed deprivation appears to rapidly reduce activity of the hypothalamo-pituitary-thyroid axis, the high correlation observed between T4 and T3 in all treatments suggests that peripheral deiodinating systems are capable of rapidly generating T3 from T4 upon realimentation. More rapid recovery of thyroid hormone production following realimentation may minimize the effects of feed deprivation on growth and feed efficiency of fish subjected to the 3-day deprivation treatment when compared to longer periods.

The effect of feed deprivation and subsequent refeeding on the bone characteristics of aged hens

In an attempt to improve skeletal integrity of older caged laying hens, birds were held without feed for 4 to 8 d and then refed. Feed deprivation caused an immediate loss in breaking force of the tibia (P < 0.05). Although bone strength increased during subsequent refeeding, values did not return to prefast levels (P < 0.05). Feed withdrawal did cause a reduction in modulus of elasticity of the tibia (P < 0.05), which is a potential benefit for bones that are more resilient to damage; this characteristic was maintained through 30 d of feeding. Histological examination of the tibia hinted at some bone remodelling during refeeding following withdrawal, although the magnitude of these changes was of limited biological significance. These data suggest that simple feed withdrawal for 4 or 8 d is insufficient to bring about a meaningful improvement in skeletal integrity of the older caged laying hen.