Explore the vast range of titles available.

Feed conversion efficiency (FCE) is an important determinant of profitability in catfish production. Understanding factors affecting FCE at a physiological level could lead to improvement of FCE at production scale. The effect of sex, family, and size grading within family on juvenile channel catfish (Ictalurus punctatus) growth, feed consumption, feed conversion, visceral fat accumulation, and weight loss during feed deprivation was determined. In Trial 1, fingerlings from five channel catfish families were graded by weight into small, large, and random mixed‐size groups, fed for 8 weeks, subjected to 2 weeks of feed deprivation, and then euthanized to determine sex. Family had a significant effect on fish growth, feed consumption, FCE, and percent weight loss during feed deprivation. Large fish had faster growth, better FCE, and lower percent weight gain than small fish from the same family. Mixed‐sized fish were generally intermediate for all measured traits. In Trial 2, all‐male, all‐female, and mixed‐sex groups of channel catfish fingerlings were subjected to the same feeding regime and then euthanized to confirm sex and weigh visceral fat. Males had a higher percent weight gain, better feed conversion, and less visceral fat than females; mixed‐sex fish were generally intermediate between all‐male and all‐female groups. FCE was positively correlated with visceral fat percentage in the all‐female treatment (i.e., fatter fish had poor feed conversion), but not in the all‐male treatment. Feed conversion and weight loss during feed deprivation were generally not correlated in either trial. This is the first report that male channel catfish convert feed more efficiently than females. Future studies should investigate the relationship between fat and feed conversion in channel catfish.

The aim of the present work was to investigate the influence of fasting and refeeding on body condition, gut physiology and microbiota in reared O. mykiss. Ninety-six fish were randomly allotted among three groups subjected to different feeding plan: C (control, fed for 5 weeks); R (restricted ration over 3 weeks followed by 2 weeks feeding); F (fasted over 3 weeks followed by 2 weeks feeding) in a well’s fresh water flow-through rearing plan. Sampling occurred at 0, 1, 2, 4, 7, 14 days during the refeeding period. At day 0 and throughout the feeding period until day 14, the weight of the fish was significantly affected by the feeding restriction. Feed deprivation reduced significantly the viscerosomatic and hepatosomatic indexes. Brush border membrane enzymes’ specific activity was modulated by feeding regimes until day 7, to level in all experimental groups at day 14. At the end of the restricted/fasted period, the microbiota of the C group was made up of 70% of Actinobacteria, 24% of Proteobacteria, 4.2% of Firmicutes and < 1% of Bacteroides, while the restricted and fasted group were characterized by a strong reduction of Actinobacteria, and a significant increase in Bacteroidetes and Firmicutes. The feed deprivation determined a dysbiosis, allowing the development of different commensal or pathogenic bacteria. In conclusion, the effects of 2 weeks of feed deprivation, excluding those related to body weight, are gradually mitigated by refeeding, which allows the restoration of digestive functions and a healthy intestinal microbiota.

Background Conventional broilers are currently one of the most efficient protein converters. Although decades of progress in genetic selection and feed formulation have lead to high standards of efficient broiler production, still a lot of variability is found between farms and between successive flocks. The aim of this study was to investigate risk- and/or protective factors for poor health and performance in conventional broiler-farms in Europe by developing eight multivariable linear mixed models. Three different models were used to investigate mortality (overall, first week, after first week), three models for performance variables (growth, feed conversion, European production index) and two models were related to slaughterhouse data (i.e. dead on arrival and condemnation rate). Results Several factors related to management and housing were significantly associated with health and performance of broilers. The following factors were associated with increased mortality: floor quality, neonatal septicemia, ventilation type and other professional activities of the farmer. The factors associated with performance were chick sex, coccidiosis infections, necrotic enteritis, dysbacteriosis, light intensity adaptations, ventilation type, comparing daily flock results with previous flock results by farmer, daily check of feed and water system and type of feed. For dead on arrival three risk factors were identified i.e. daily growth, type of light adaptation and type of drinkers system. For condemnation rate seven risk factors were found, i.e. type of drinking system, daily growth, feed withdrawal time, type of ventilation, house size, septicemia after seven days and type of feed. Conclusions These results imply that a multifactorial approach is required with adaptations involving both improvements in management, housing, health programs and an increasing level of professionalism of the farmer in order to improve broiler performance and health.

Pre-slaughter handling practices, such as fasting, transport, mixing and human interventions affect the welfare of pigs and carcase and meat quality individually and cumulatively. Behavioural and physiological studies conducted during the pre-slaughter period revealed that producer-controlled factors at the farm, such as housing system, previous handling experience, genetics, gender, nutrition and slaughter weight can have an impact on pigs' ease of handling and sensitivity to stress, which result in loss of profits for the pork chain due to transport losses, reduced carcase value due to lesions and bruises and meat quality defects. Research has shown that pigs originating from enriched housing conditions, not over-selected for lean deposition and trained to be handled are easier to handle and more resilient to the effects of physical stress prior to slaughter. However, the effects on meat quality are not clear. The production of entire males and immunocastrates can be a valid alternative to surgical castration, provided specific practices are applied to limit aggressiveness in mixed group situations and the risk of bruised carcases. Recommendations for the transport and handling of heavier slaughter pigs must be adapted to improve ease of handling and reduce transport losses, aggressiveness and fatigue-related meat quality defects. The response of pigs to pre-slaughter physical stress and feed deprivation can be affected by ractopamine dietary supplementation, feed composition and feeding regime. The objective of this paper is to overview the effects of on-farm producer-controlled factors on pigs' response to pre-slaughter handling and meat quality, and environmental, social and economic sustainability. HIGHLIGHTS On-farm factors impact pig losses On-farm factors impact ease of handling On-farm factors impact food safety; effects on meat quality are unclear

The effects of intermittent starvation on the growth, precocity, digestive enzyme activity, feeding, and body chemical composition of the juvenile Chinese mitten crab Eriocheir sinensis were investigated in two independent experiments. Crabs were reared individually during Experiment I and cultured in aggregate during Experiment II. Five treatments were tested in both experiments. Crabs in the control group (Group C) were fed continuously and, in Groups S3, S6, S10, and S15, were starved and then re-fed for 3, 6, 10, and 15 days, respectively. The precocity rate of Group C was significantly higher than that of the other groups. In Experiment I, the final mean body weight and the mean specific growth rate in dry matter of Groups C and S3 were significantly higher than those of the other groups. In Experiment II, the mean specific growth rate in body weight in Group C was similar to that of Groups S3, S6, and S10 but significantly higher than that of Group S15. Crabs in Groups S3, S6, and S10 compensated for starvation-induced growth depression after being re-fed, and compensatory growth was achieved via both higher feeding rate and improved feed efficiency. There was no significant difference in trypsin and alkaline phosphatase activity, while steapsin and amylase activity were significantly affected by the starvation period. There was no significant difference in dry matter, ash, and protein content among Groups C, S3, S6, and S10 in Experiment I. The results demonstrated that proper intermittent starvation was sufficient for reducing the precocity rate of cultured juvenile E. sinensis , and it is recommended that juvenile crabs be subjected to intermittent fasting for 6 to 10 days to maintain precocity rates at acceptable levels without inhibiting growth and yield.

Transport conditions have the potential to alter the physiological responses of animals to the psychological or physical stress of transport. Transportation may introduce multiple physical and psychological stressors to unweaned calves and adult cattle, including noise, overcrowding, food and water deprivation, extreme temperatures, commingling with unfamiliar animals, handling by unfamiliar humans, and being placed in a novel environment upon arrival. Apart from these factors, the type of road and even driving skill may affect the welfare of animals. One of the concerns regarding cattle transport is that the handling and marketing of animals prior to a journey may lengthen the period of feed withdrawal. Furthermore, feed withdrawal can impact animal welfare through hunger and metabolic stress. Transportation is also associated with a decrease in animal performance as well as an increase in the incidence of bovine respiratory disease. It is well established that the transportation of cattle is a stressor that causes a quantifiable response; however, excessive stress during transport resulting in physiological or pathological changes can be reduced with best management practices. The objective of this review was to analyse the available scientific literature pertaining to the transport by road of cattle, including unweaned calves.

Leptin is a cytokine that regulates appetite and energy expenditure, where in fishes is primarily produced in the liver and acts to mobilize carbohydrates. In most fishes there is one leptin receptor (LepRA1), however, paralogs have been documented in a few species. Here we revealed a second leptin receptor (LepRA2) in rainbow trout that has a 77% amino acid sequence identity to trout LepRA1 and 93% to salmon LepRA2. Phylogenetic analyses show the salmonid specific genome duplication event as the probable origin of the second LepR in trout. A tissue distribution showed tissue specific expression of these receptors, with lepra1 levels highest in the ovaries, nearly 50-fold higher than lepra2. Interestingly, lepra2 mRNA was most highly expressed in the liver while hepatic lepra1 was virtually undetectable. To evaluate the effects of these receptors under catabolic conditions, we exposed rainbow trout to a two-week period of feed deprivation. Body indices declined in the feed restricted group at one and two weeks and plasma leptin was lower in fasted fish at one week. Hepatic lepra2 mRNA increased 1.5-fold by one week and remained elevated at two weeks of fasting, while expression of lepra1 remained low. By contrast, muscle lepra1 increased 2- and 3-fold at one and two weeks of fasting, respectively, while adipose lepra1 was lower in fasted fish. lepra2 transcript levels were not affected in muscle and fat. These data show lepra1 and lepra2 are differentially expressed across tissues and during feed deprivation, suggesting paralog- and tissue-specific functions for these receptors.

Starvation and refeeding is an efficient method to excel the quality of the harvesting yields and reduce feeding costs. The purpose of this study was to investigate the effects of low-, moderate-, and severe-intensity starvation on compensatory growth and economic efficiency of Pacific white shrimp Litopenaeus vannamei. Five feeding strategies were designed: feeding every day (C); starving for 1 day followed by 4-day refeeding (T1); starving for 2 days followed by 8-day refeeding (T2); starving for 4 days followed by 16-day refeeding (T3); and starving for 8 days followed by 32-day refeeding (T4). All treatments were fed for a total of 32 days during a 40-day experiment. Low and moderate starvation did not significantly affect growth indices including weight, length, specific growth rate (SGR), feed conversion ratio (FCR), and biomass in T1, T2, and T3 compared with C (p > 0.05), while T4 exhibited lower (p < 0.05) growth rate. Moreover, no significant differences were observed in survival, protein efficiency ratio (PER), and net protein utilization (NPU) among the control and other experimental treatments. Nevertheless, a higher protein and lipid content was observed in T1, T2, and T3 in comparison with C. The economic conversion ratio (ECR) and feeding cost reduction were similar and suggested that T1 showed the highest economic efficiency (p < 0.05). These results revealed that low- and moderate-intensity starvation significantly improved the compensatory growth, survival, protein utilization efficiency, and body composition of L. vannamei, while the lowest economic efficiency can be attributed to severe starvation and refeeding intervals.

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.

The intestine performs the critical roles of nutrient acquisition, tolerance of innocuous and beneficial microorganisms, while retaining the ability to respond appropriately to undesirable microbes or microbial products and preventing their translocation to more sterile body compartments. Various components contribute to antimicrobial defenses in the intestine. The mucus layer(s), antimicrobial peptides and IgA provide the first line of defense, and seek to trap and facilitate the removal of invading microbes. If breached, invading microbes next encounter a single layer of epithelial cells and, below this, the lamina propria with its associated immune cells. The gut immune system has developmental stages, and studies from different species demonstrate that innate capability develops earlier than acquired. In addition, various factors may influence the developmental process; for example, the composition and activity of the gut microbiota, antimicrobials, maternally derived antibodies, host genetics, and various stressors (e.g. feed deprivation). Therefore, it is clear that particularly younger (meat-producing) animals are reliant on innate immune responses (as well as passive immunity) for a considerable period of their productive life, and thus focusing on modulating appropriate innate responses should be an intervention priority. The gut microbiota is probably the most influential factor for immune development and capability. Interventions (e.g. probiotics, prebiotics, antibodies, etc.) that appropriately modulate the composition or activity of the intestinal microbiota can play an important role in shaping the desired functionality of the innate (and acquired) response. In addition, innate immune mediators, such as toll-like receptor agonists, cytokines, etc., may provide more specific ways to suitably modulate the response. A better understanding of mucosal immunology, signaling pathways, and processes, etc., will provide even more precise methods in the future to boost innate immune capability and minimize any associated (e.g. nutrient) costs. This will provide the livestock industry with more effective options to promote robust and efficient productivity.