Restricted Feeding Regime Research Articles

ENERGY BALANCE UNDER RESTRICTED FEEDING IN RUMINANTS

Forty-eight adult local desert non-pregnant and non-lactating females, age 4-5 yrs.; Barki sheep (n= 16 and average body weight 34.53 ±1.56 kg), Balady goats (n= 16 and average body weight 31.11 ± 1.63 kg), and Shami goats (n=16 and average body weight 28.08±0.92 kg) were used to study effects of long-term restricted feeding regime on body weight changes and balance of energy and protein. Animals of each species were allocated to two levels of feed intake; control feeding treatment (CON) where animals fed a diet at a level of feeding to meet approximately the metabolizable energy for maintenance requirement (MEm), while those on the other dietary treatment was fed almost 50% of these quantities on a BW basis, termed as the restricted treatment (restricted; RES). Alfalfa hay and concentrate feed mixture (50:50% as DM basis) were given based on requirement recommendations. The results could be summarized as follows: 1-Comparison between Balady goats (BG) and Sheep (SH): The ADG was not affected (P<0.05) by animal species (BG vs. SH), however, it was affected (P<0.01) by feed intake level where the RES animal group showed a negative ADG (-65.6 g/d) compared with the CON group that achieved positive ADG (36.4 g/d). Both of SH and BG had similar negative energy balance (EB) values (67.0 vs. 61.4 KJ/ kg0.75/d, for BG and SH respectively). Nitrogen balance (NB) was greater (P<0.01) for SH (107.64 mg/kg0.75/d ) vs. BG (89.47 mg/kg0.75/d) and was greater (P<0.01) for animals fed on CON intake (251.47 vs. 208.55 mg/kg0.75/d, respectively) than those fed on RES intake (-36.18 vs. -29.62 mg/kg0.75/d, respectively), which gave a negative NB. 2.Comparison between Balady goats (BG)and Shami goats (SG): The ADG was not affected (P< 0.05) by animal species (BG vs. SG) being corresponding values 45.1 and 40.6 g/d respectively. However, ADG was affected (P< 0.001) by feed intake level where the RES animal group showed a negative ADG (-55.6 g/d) compared with the CON group that achieved positive ADG (30.1 g/d). Under CON intake, EB was an insignificant decrease in SG compared to BG. However, under RES intake both BG and SG had a negative energy balance (kJ/kg0.75/day) and it was lower (P<0.01) in SG than that in BG. Animals fed on the CON intake level had a greater (P<0.01) value for EB compared to those fed on RES intake and the latter gave a negative balance. Nitrogen balance (NB, mg/kg0.75/day) was a trend to be greater (P<0.10) for SG vs. BG. Also, animals under the CON intake level captured more nitrogen than their counterparts, which lost a large amount of nitrogen. Also, the retention N was increased (P<0.01) in SG than BG under the CON intake level, however, all breeds were lost N under the RES intake level especially in SG (-76.37) followed by BG (-29.62). It could be concluded that with hot conditions, sheep may have an advantage in a decreased Metabolizable energy for maintenance (MEm) requirement and reduction in heat production of a magnitude adequate to maintain body weight. There is a similar rate of using the energy between sheep and goats with moderate or limited nutrition planes. It is clear that Balady goats are better than Shami goats in their ability to reduce the energy expenditure via reducing the rate of metabolism when they were fed on restricted intake.

An in vivo evaluation of the effects of feed restriction regimens on wooden breast using ultrasound images as a predictive tool

ABSTRACT 1. Gradual feed restriction was applied to broilers in order to reduce growth rate and, as a consequence, gradually impacts wooden breast myopathy occurrence. Ultrasound (US) images of breast muscle in live birds were correlated with breast fillets presenting wooden breast characteristics (WB). 2. A total of 1800 Cobb × Cobb 500 slow-feathering male chicks were fed one of the six feed restriction treatments with 12 replicates of 25 birds each, in a completely randomised design. Birds were fed ad libitum or were pair-fed to 50%, 60%, 70%, 80% or 90% of normal ad libitum intakes from 8 to 49 d to provide a gradual reduction in growth rate. Ultrasound images were obtained weekly from all birds and, in parallel, one bird per pen was weekly slaughtered and the major breast muscle was weighed and WB graded as 0 (normal), 1 (mild hardening in the upper), 2 (moderate hardening in the upper and/or lower), 3 (severe hardening) and 4 (severe hardening with haemorrhagic lesions and yellow fluid). Blood was taken for analysis of enzymes related to muscle cell breakdown. 3. Feed restriction applied at 50%, 60%, 70%, 80% and 90% of the ad libitum feed intake (FI) resulted in decreased body weight gain (BWG; P ≤ 0.05). 4. From 21 to 49 d, the increasing feed restriction led to linear increases (P ≤ 0.05) in WB scores, fibre density as well as breast depth and breast echogenicity. Creatine kinase, lactate dehydrogenase and aspartate aminotransferase concentration decreased linearly when broilers were feed restricted (P ≤ 0.05). 5. Wooden breast was positively correlated with echogenicity at 21 d (r = 0.510), 28 (r = 0.531), 35 (r = 0.470), 42 (r = 0.430) and 49 d (r = 0.548) (P ≤ 0.001). The use of breast echogenicity can be an additional tool to early detect alterations related to wooden breast.

Partial and total replacement of fish oil with fatty acid ethyl esters in the starter diets of rainbow trout (Oncorhynchus mykiss)

Fatty acid ethyl esters (FAEE) are a potential alternative to fish oil as a source of polyunsaturated fatty acids in fish feeds. This investigation examined the growth performance, lipid composition, and intestinal and liver histology of rainbow trout (Oncorhynchus mykiss) fed experimental starter diets with graded levels of FAEE and fish oil. Five experimental diets were formulated with 20% total lipid content and 0%, 25%, 50%, 75%, and 100% replacement of Alaskan Pollock oil with FAEE oil, and they were formulated with analogous fatty acid levels. The five diets used defatted fish meal as the primary protein source, and a sixth diet was included that used full-fat fish meal and extracted fish oil. Triplicate groups of rainbow trout (144 ± 20 mg initial weight) were fed experimental diets for 62 days on a restricted feeding regime (4–5.5% biomass/day). The group fed the full-fat fish meal diet had faster growth and a lower feed conversion ratio than the defatted fish meal diet groups after 31 and 62 days of feeding. The growth rate and feed conversion ratios of fish were significantly different between the FAEE-containing diet groups in the first 31 days of feeding, but were not significant from 32 to 62 days of feeding. Fatty acid analysis showed similarity between the fatty acid profiles in experimental diets and in fish muscle and liver tissues at the end of the experiment (all groups mean weight ~3.6 g/fish). Satiation feed intake for a single day was measured at 31 days of feeding, and feed intake was higher in the 100% FAEE diet than the control (8.3 ± 1.1% vs 6.4 ± 0.3% daily satiation ratio). This result suggests that FAEE has a positive effect on voluntary feed intake. Histological analysis of posterior intestine enterocytes and hepatocytes showed a significant reduction in lipid vacuole size in the 100% FAEE group, relative to the defatted and full-fat fish meal control groups. These results suggest that rainbow trout had utilized diet with ≥50% FAEE less efficiently in the first feeding phase, likely due to reduced fatty acid absorption, but that these trends were diminished as fish grew to a larger size.

Effects of cyclical short-term food deprivation and refeeding on compensatory growth and gene expression of SOD, GPX and HSP70 in Schizothorax wangchiachii

The present study evaluated the effects of cyclical short-term food deprivation and refeeding on growth performance, body composition, and gene expression of SOD, GPX and HSP70 in Schizothorax wangchiachii.The experimental design included four feeding protocols for eight weeks: feeding every day of the week (control), starvation for one day and refeeding for six days per week (S1F6 treatment), starvation for two days and refeeding for five days per week (S2F5 treatment), and starvation for three days and refeeding for four days per week (S3F4 treatment). The results showed that no significant difference in final body weight, specific growth rate and feed conversion efficiency were observed among the treatments (P > 0.05).The feeding rate significantly increased with the duration of food deprivation per week compared to the control (P < 0.05). The expression levels of HSP70 showed no significant differences in the gill, liver and spleen of S.wangchiachii subjected to different feed restriction regimes(P > 0.05), but in the kidney, the expression levels of HSP70 were significantly downregulated in S1F6 and S2F5 compared to the control(P < 0.05). The expression levels of SOD and GPX in the examined tissues were not affected by the different feed restriction regimes(P > 0.05). In conclusion, full compensatory growth was observed in S.wangchiachii under eight cycles of food deprivation and refeeding. Hyperphagia was the main mechanism of compensatory growth of S.wangchiachii.

Impact of restricting feed and probiotic supplementation on growth performance, mortality and carcass traits of meat-type quails.

The objective of this study was to evaluate the effects of quantitative feed restriction, along with dietary supplementation with a probiotic blend (Protexin) as a natural growth promoter, on the performance, water consumption, mortality rate and carcass traits of meat-type quails. A total of 250 1-day unsexed quails were randomly allocated to five equal groups in a completely randomized design. The first group (A) fed a basal diet without any restriction (24hr/day); the second group (B1) fed the basal diet for 20hr/day; the third group (B2) fed the basal diet enriched with probiotic (0.1g/kg diet) for 20hr/day; the fourth group (C1) fed the basal diet for 16hr/day; and the fifth group (C2) fed the basal diet enriched with probiotic (0.1g/kg diet) for 16hr/day. Birds were fed ad-libitum from 0-14days of age, and then the feed restriction regimes started from 14 till 28days of age. Results showed that quails in the control-group consumed more feed and water than the other treatment groups (p<.01), however their body weights did not differ (p>.05) compared with the other treated groups. The best feed conversion values were achieved in quails supplemented with probiotic blend (B2 and C2) in comparison with the other groups (p<.01). Feeding probiotic had a positive effect on bird health which reduced the mortality rate. Further, mortality rate was significantly reduced (p<.05) by feed restriction, with or without probiotic supplementation. No carcass parameters were significantly affected (p>.05) by treatments. Our results show that quail could be reared under a feed restriction system, for 4-8hr daily, along with dietary supplementation of probiotic as growth promoter for better growth performance.

Reproductive Performance of Japanese Quail Hens (Coturnixcoturnix japonica) Fed with Feed Restriction Regimes during Growth Period

Reproductive performance of quail hens (Coturnixcoturnix japonica) at sexual maturity was evaluated following two feeding restriction programs (100%, 90% and 80% of ad libitum) and energy metabolism (EM) of ration: 2900 Kcal/kg and 2800 Kcal/kg) between 2 weeks and 5 weeks of age with five replicates of 10 chicks per replicate. Body weight and feed conversion were measured weekly during feed restriction. After experimental feeding treatment, age at first egg, BW, egg weight, development of reproductive organ on sexual maturity were evaluated of one hen’s quail per treatment. The results of the experiment indicated that the restricted feeding until 80% of ad libitum was consequently (p 0.01) delayed sexual maturity and influence the development of the reproductive organ. However, it did not show significant influence on the body weight of the first-laid egg and initial egg production. Restricted feeding at 90% of ad libitum and EM ration 2900 Kcal/kg showed the best results for quail feed management during growth.

Ghrelin receptor in agouti-related peptide neurones regulates metabolic adaptation to calorie restriction.

Ghrelin is a gut hormone that signals to the hypothalamus to stimulate growth hormone release, increase food intake and promote fat deposition. The ghrelin receptor, also known as growth hormone secretagogue receptor (GHS-R), is highly expressed in the brain, with the highest expression in agouti-related peptide (AgRP) neurones in the hypothalamus. Compelling evidence indicates that ghrelin serves as a survival hormone with respect to maintaining blood glucose and body weight during nutritional deficiencies. Recent studies have demonstrated that AgRP neurones are involved in metabolic and behavioural adaptation to an energy deficit to improve survival. In the present study, we used a neuronal subtype-specific GHS-R knockout mouse (AgRP-Cre;Ghsrf/f ) to investigate the role of GHS-R in hypothalamic AgRP neurones in metabolic and behavioural adaptation to hypocaloric restricted feeding. We subjected the mice to a restricted feeding regimen of 40% mild calorie restriction (CR), with one-quarter of food allotment given in the beginning of the light cycle and three-quarters given at the beginning of the dark cycle, to mimic normal mouse intake pattern. The CR-fed AgRP-Cre;Ghsrf/f mice exhibited reductions in body weight, fat mass and blood glucose. Metabolic profiling of these CR-fed AgRP-Cre;Ghsrf/f mice showed a trend toward reduced basal metabolic rate, significantly reduced core body temperature and a decreased expression of thermogenic genes in brown adipose tissue. This suggests a metabolic reset to a lower threshold. Significantly increased physical activity, a trend toward increased food anticipatory behaviour and altered fuel preferences were also observed in these mice. In addition, these CR-fed AgRP-Cre;Ghsrf/f mice exhibited a decreased counter-regulatory response, showing impaired hepatic glucose production. Lastly, hypothalamic gene expression in AgRP-Cre;Ghsrf/f mice revealed increased AgRP expression and a decreased expression of genes in β-oxidation pathways. In summary, our data suggest that GHS-R in AgRP neurones is a key component of the neurocircuitry involved in metabolic adaptation to calorie restriction.

Implementation of different feeding regimes and flashing light in broiler chicks

A 3 × 2 factorial arrangement was implemented to determine the performance of 450 Cobb broilers subjected to different feeding regimes with and without lighting programs. The chicks were divided into 3 groups according to the feeding regime (ad libitum, restricted, or intermittent), and each group was reared under one of two lighting programs (100% continuous light or 50% continuous light and 50% flashing light). The results showed that the broilers under the ad libitum and intermittent feeding regimes had superior body weight (BW) and average daily gain (ADG) values and the lowest feed conversion ratio (FCR) at 3 and 6 wk of age. Broilers exposed to flashing light and an intermittent feeding regime had the highest BW and ADG values and the lowest FCR. Birds exposed to intermittent feeding had the highest dressed carcass weight and the lowest heart weight. Broilers reared with flashing light had higher tenderness and juiciness values than the other groups. Broilers subjected to a restricted feeding regime and flashing light had the lowest abdominal fat values of all the groups. Tenderness and juiciness were significantly higher in broilers subjected to the ad libitum feeding regime × flashing light and the intermittent feeding regime × flashing light. Broilers fed an intermittent regime had the lowest spleen %, heterophil, heterophil to lymphocyte (H/L) ratio and body temperature values of all the groups, and broilers reared under the intermittent regime × flashing light had the lowest spleen %, H/L ratio and body temperature values. Non-significant differences in all health aspects (shank length, keel bone length, foot pad burns, breast blisters score, hock discoloration, and mortality) were observed among the experimental groups. In conclusion, intermittent and restricted feeding regimes and a flashing lighting program improved the FCR and did not produce any adverse effects on performance or physiological parameters. The results of this work show that intermittent feeding and flashing lighting programs are more beneficial to broiler management.

Effects of level of intake of a 50% concentrate pelleted diet on metabolizability by mature Katahdin wethers

Ten adult Katahdin sheep wethers (74.3 ± 2.03 kg initial BW), approximately 3 yr of age, were used in a crossover experiment to study effects of a restricted feeding regime on digestibility, metabolizability, and heat energy. A 50% concentrate pelleted diet was fed near the ME requirement for maintenance (Control; DM intake = 44.4 g/kg BW0.75) and at 55% of this level (Restricted; DM intake = 24.4 g/kg BW0.75). Periods were 4 wk in length, with 3 wk for adaptation, measures in the final week when animals were situated in metabolism cages, and 2 days for gas exchange quantification via a head-box respiration calorimetry system. Apparent total tract digestibilities of DM (68.9 and 76.1%; SEM = 1.08), OM (78.3 and 83.3%; SEM = 1.57), CP (74.6 and 80.7%; SEM = 1.68), NDF (50.9 and 61.9%; SEM = 3.23), and gross energy (77.9 and 83.0%; SEM = 1.59) were greater (P < 0.05) for Restricted than for Control. Expressed in MJ/day, energy in urine (1.03 and 0.67; SEM = 0.294) and ruminally emitted methane (1.03 and 0.77; SEM = 0.076) were greater for Control vs. Restricted (P < 0.05), but as a percentage of gross energy were at least numerically greater for Restricted (urine: 5.63 and 6.48%, SEM = 2.218 and P = 0.594; methane: 5.46 and 7.16% for Control and Restricted, respectively, SEM = 0.579 and P = 0.030). As a consequence, ME intake as a percentage of gross energy intake did not differ (P = 0.354) between treatments (66.8 and 69.4% for Control and Restricted, respectively; SEM = 2.89). The treatment difference in heat energy (11.05 and 9.29 MJ/day; SEM = 0.563) was less than in ME intake (12.67 and 7.30 MJ/day for Control and Restricted, respectively; SEM = 0.508); thus, recovered energy differed from 0 (P < 0.05) and was greater for Control vs. Restricted (1.62 and −1.99 MJ/day; SEM = 0.661). In conclusion, restricted feed intake had marked influence on digestibility, although energy losses in urine and methane energy compensated so that metabolizability did not differ between treatments. With a diet of this nature a similar ME concentration could be assumed for studies with hair sheep fed near the standard maintenance requirement and restricted in intake.

English

An experiment was conducted in a completely randomized design to study the effect of physical feed restriction on broilers’ performance during the starter period. Two hundred and forty one-day-old unsexed (Hubbard) broiler chicks were randomly distributed in six treatments; there were five replicates with eight chicks per a replicate. Treatment A: fed ad libitum (control). Restricted groups were restricted at selected percentages of the ad libitum intake of the full fed controls. The percentages were: B= 90%, C= 80%, D= 70%, E= 60% and F= 50%. Feed restriction was applied from 8-28 days of age. The experiment lasted for six weeks. Control birds showed significantly (p<0.05) higher body weight and carcass cuts weight than restricted ones. Feed conversion ratio was not affected by feed restriction regimen applied in the present study. Restricted birds failed to compensate for the loss in weight due to prolonged feed restriction period. Key words: Broiler chicks, performance, physical feed restriction, starter period.

Effects of different feeding frequencies on growth, cataract development and histopathology of lumpfish (Cyclopterus lumpus L.)

Three duplicate groups of individually tagged lumpfish (mean initial weight: 22.3 ± 2.5 g) were fed either daily (7DW); four days per week (4DW) or three days per week (3DW) at a feeding rate of 2% body weight day−1 for a period of 126 days. There were significant differences in growth rates between the groups with the 7DW fish having the highest growth rates. Cataract prevalence was 53% lower in the 3DW group compared to the 7DW group. Histological examination showed that in some individuals in all three groups there was moderate expansion of the lamina propria in the mid and hind gut regions of the intestine with tissue most likely to represent fibrous tissue with scattered leucocytes. The severity of inflammation appeared to increase the more frequent the fish were fed with the 7DW fish having the highest inflammation score in these tissues. Feeding fish daily also resulted in higher levels of liver vacuolisation and chronic inflammation of the lamina propria in the mid and hind gut region of the intestines. Results from the present study show that restricted feeding regimes can be used to control growth and improve gut and eye health in lumpfish.

Genotype by environment interaction for feed efficiency trait of the juvenile Pacific white shrimp Litopenaeus vannamei held in individuals vs. in groups

To understand the influence the individual-rearing design will exert on selective breeding programs for feed efficiency trait of L. vannamei, this study assessed the extent of genotype by environment (G × E) interaction for feed efficiency of 15 full-sib families reared in individuals vs. in groups. Feed efficiency ratio (FER), average daily weight gain (ADG) and daily feed intake (DFI) were measured on individuals of the families in individual-rearing condition and on groups of individuals of the same families in group-rearing condition, respectively, with a restricted feeding regime. As the experimental design, each family was divided into three groups in both rearing conditions, and a total of 90 group records were used for G × E analysis. In this study, increased FER and ADG denoted as least squared means were observed in group-rearing condition compared to individual-rearing condition. Genetic variance was much higher than G × E and environmental variances for both FER and ADG, but G × E variance was higher than genetic and environmental variances for DFI. Genetic correlations between the two conditions were 0.786 and 0.909 for FER and ADG, respectively, which indicates a mild G × E interaction effect for FER and an insignificant G × E interaction effect for ADG. These results suggest that for family selection the decisions based on individual-rearing design might be applicable for production situation where shrimp are held in social groups and individual-rearing design is feasible in breeding programs for feed efficiency of L. vannamei.

The effect of different feeding rates and restriction on the growth performance of Clarias gariepinus.

This study seeks to investigate the effect of restricted feeding regimes at different rate on growth performance of Clarias gariepinus using static and flow through system. Fingerlings were divided into six batches for each systems with the first and second batch fed at 5% body weight (BW) every day and every other day respectively, the third and fourth batch were fed 10% BW every day and every other day respectively while the fifth and sixth batch were fed 15% BW every day and every other day respectively. Result obtained shows that fish fed every other day exhibited compensatory growth at 5% BW in the static system while in the flow through system fish grow better at all feeding rates when fed every other day. Increasing feeding rate however beyond 10% BW did not improve growth when fed every day or every other day in the static system due to poor water quality. This therefore implies that catfish farming can make more profit feeding African catfish at 5% body weight every other day in the static system and up to 15% body weight (every other day) in flow through system, hence taking advantage of the compensatory growth response phenomenon.

Chicory and red clover silage in diets to finishing pigs\u2014influence on performance, time budgets and social interactions

Ley crops can be preserved as silage and can serve as a locally produced feedstuff/enrichment for pigs. It is important to determine the potential for using ley crops grown on-farm in pig production and to evaluate dietary inclusion of different roughage types on pig performance and behaviour. This study examined the influence of access to chicory or red clover silage, in combination with a restricted feeding regime, on pig performance, time budgets and social behaviour. In total, 72 finishing pigs were evenly allocated to three treatments: chicory silage, red clover silage and a control. Pigs in the control treatment were fed 100% commercial liquid feed according to the standards for growing/finishing pigs, while pigs in the chicory and red clover treatments were fed 80% commercial diet (energy basis) and whole-crop chicory or red clover silage ad libitum. Pigs in the chicory silage and red clover silage treatments grew 15 and 10% slower, respectively, than pigs in the control treatment; however, the slower growth rate was not as pronounced as the reduction of energy allowance in the commercial feed. Further, the pigs fed red clover silage had lower feed conversion ratio (based on the commercial cereal-based feed) than pigs fed chicory silage or the control diet, indicating that the red clover silage contributed some energy and nutrients to the finishing pigs. Moreover, pigs fed chicory or red clover silage were more active than control pigs and performed more feed-directed behaviours and less behaviours directed towards other pigs and pen fitting.

Regulation of compensatory growth by molecular mechanism in Labeo rohita juveniles under different feeding regimes

A study was carried out to assess the regulation of compensatory growth under different restriction feeding regimes in Labeo rohita juveniles by the interaction of various feed intake and growth regulating genes. A 60 day feeding trial was conducted with five treatment groups, Control (3% body weight, bw), T1 (alternate days), T2 (0.5% bw), T3 (1% bw) and T4 (2% bw) and feeding was done for first 30 days of the trial. For next 30 days, all the treatment groups were fed at a rate of 3% bw as in the control group. There was significant (p < 0.05) difference in the weight gain among the treatment groups with lowest FCR and highest PER was found in T2 group. Ghrelin gene mRNA levels were upregulated during first 30th days of the trial with highest expression levels in the T2 group. The expression levels of leptin gene mRNA were found significantly different (p < 0.05) among the treatments, which was down-regulated during initial 30 days and upregulated as the experiment progress towards 60th day. The IGF-1 mRNA expression levels were upregulated more in liver compared to the muscle tissue. The results of the study suggest that increased ghrelin levels and decreased leptin levels lead to hyperphagia during the onset of refeeding, which further triggers the compensatory growth in L. rohita. The present study describes the molecular mechanism behind the compensatory growth following a different feed restriction regime in L. rohita which is regulated due to the interaction of different energy homeostasis and growth regulating genes.

Effect of long-term food restriction on reproductive performances in female yellowtail, Seriola quinqueradiata

In aquaculture of species with a large body size, such as tuna and yellowtail, a major profitability concern is that broodstock management for egg collection incurs high feeding costs and labor. In order to reduce feeding costs, development of restricted feeding techniques without affecting the reproductive performance may be useful. To gain a better understanding of the potential significance of capital energy in reproduction of large fish with income breeding patterns, we examined the effects of long-term restricted feeding prior to the onset of oocyte development on reproductive performance in female yellowtail (Seriola quinqueradiata). A control group was fed to satiety, while experimental groups were restricted to 50 and 25% of the ration administered to the control group from July to December. The females subjected to restricted feeding had lower ovary weight and smaller ovarian follicles than did the control females in February. Moreover, plasma 17β-estradiol levels in food-restricted females were significantly lower than those in normally fed females in January and February. Furthermore, we found that food-restricted females had lower pituitary gene expression levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone) in January. These results suggest that severe food restriction during the immature phase delays initiation of oocyte development via an alteration in pituitary gonadotropin production in yellowtail females. Once food intake was sufficient after switching to the satiation feeding regime, however, oocyte development rapidly advanced, resulting in the production of fully functional eggs. Overall, these findings demonstrate that the yellowtail displays a mixed strategy of capital-breeding patterns at the onset of sexual maturation, but stronger income-breeding patterns with its progression in reproduction with energy acquired during the vitellogenic phase. Additionally, food deprivation over 6months by 50% of the amount of food required for satiation during the immature phase did not change reproductive performance in female yellowtail, although the females in the 25% feeding group showed a lower percentage of normally hatching eggs. Therefore, a 50% restricted feeding regime before the onset of sexual maturation is acceptable for reducing feeding costs in broodstock management without affecting reproductive performance.

Effect of timing of restricted feeding on sexual maturation in female yellowtail, Seriola quinqueradiata

In aquaculture of species with a large body size such as tuna and yellowtail, a major problem still is that broodstock management for egg collection requires high feeding cost and labor. In order to reduce feeding costs, development of restricted feeding techniques without affecting the reproductive performance may be useful. To gain a better understanding of reproductive responses to food supply, we examined the effect of restricted feeding during the previtellogenic and vitellogenic phases on sexual maturation in female yellowtail, Seriola quinqueradiata. Restricted feeding during the vitellogenic phase tended to reduce ovary weight relative to normally fed controls at the end of the experiment. Histological observations revealed that both restricted feeding regimes do not affect the percentage of atretic follicles as compared to the control group. Nevertheless, the mean diameter of the most advanced follicles of the females subjected to restricted feeding during the vitellogenic phase was significantly smaller to normally fed controls. These results suggest that reduced food intake during the vitellogenic phase is likely to delay oocyte growth, and lead to low ovarian weight. Endocrine analyses showed that restricted feeding during the vitellogenic phase reduced plasma 17β-estradiol levels, but not plasma and pituitary gene expression levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone) at the end of the experiment. Transcripts for ovarian steroidogenesis-related genes, such as P450 side-chain cleavage (cyp11a1) and 3β-hydroxysteroid dehydrogenase (hsd3b) after food restriction during the vitellogenic phase tended to be high. Therefore, the effects of restricted feeding on reproduction would not be mediated by alterations in circulating gonadotropin levels, but rather through direct effects on the ovarian steroid production in yellowtail females.

Feed restriction regime in a rabbit line selected for growth rate alters oocyte maturation manifested by alteration in MSY2 gene expression.

Young rabbit females selected for growth rate may have nutritional needs, which may not be met with the common practice of feed restriction during rearing in commercial rabbit production. The aim of this study was to analyse whether two different feeding programmes: ad libitum or restricted (130g/day) feeding, applied in young rabbit females for 1month at the end of rearing, could modulate the origin of ovulation process and the quality of the oocytes. At 16weeks of age, 34 females were randomly assigned to restricted or ad libitum feeding, maintaining these conditions for a month. Then, in an initial experiment, transcriptional profiling of hypothalamus-hypophysis tissue was performed to assess failure to ovulate. In the second experiment, the gene expression analysis of some candidate genes related to oocytes quality was performed. Our results demonstrated that neither of the two feeding programmes modified the transcription of hypothalamus-hypophysis tissue, while the only differences in MSYR expression were found in in vivo mature oocytes ready for successful fertilization. Specifically, MSYR was over-expressed in oocytes from females fed ad libitum. MSYR is one of the most abundant proteins in the oocyte and has proven to be a key regulator of maternal RNA transcription and translation. This finding suggests that MSYR gene is a promising gene in our understanding of the relationship between high growth rate and reproductive performance decline.

Response of slow-growing chickens to feed restriction and effects on growth performance, blood constituents and immune markers

An experiment was conducted to study the response of a slow growing chickens breed “Sinai” to feed restriction (FR) and the effects on growth performance, blood constituents and immune markers using a total number of 60 unsexed 7-d-old chicks. Chickens were housed in battery brooders during d 1 to 35 of age and randomly distributed keeping similar initial body weight, in two FR treatment groups. During 0-6 d of age, chickens were fed ad libitum, a mash commercial diet. During d 7-14 of age, chickens were fed either 100 or 80 % of the daily amount of feed consumed by the control group during the previous day. From d 15 to d 35, chickens were fed ad libitum diets a mash commercial diet. At the end of the experiment, body weight gain on the FR regimen was significantly lower than that of the control group, but feed intake and feed conversion ratio (FCR) were not affected. In addition, red blood cells parameters and white blood cells traits were not negatively affected. However, hemagglutination inhibition titter for New castle disease virus, monocyte and total cholesterol were significantly decreased by FR regimen, but blood plasma albumin and immunoglobulin A significantly increased. In conclusion, slow growing chickens could tolerate 27.2 % FR during the 2nd week of age without significant differences in feed intake and FCR for the whole period, and general health status and metabolic profiles indicating a compensatory growth during 15-35 d of age although growth was in favour to the unrestricted group.

Prophylactic use of a standardized botanical extract for the prevention of naturally occurring diarrhea in newborn Holstein calves

The objectives of this study were to evaluate the prophylactic use of SB-300 (Jaguar Animal Health, San Francisco, CA), a standardized botanical extract isolated from the bark latex of Croton lechleri, on reducing fecal water losses and diarrhea events in Holstein bull calves individually housed under a restricted whole-milk feeding regimen (6 L/d) from 1 to 25 d of life. Fluid therapy administration due to dehydration, average weight gain, and the fecal microbiome were also evaluated. Bull calves used in this study were born from normal parturition, fed 4 L of pooled pasteurized colostrum by esophageal feeder, and moved to a research facility at Cornell University (Ithaca, NY). A double-blinded randomized clinical trial was designed to allocate a total of 40 newborn calves into 1 of 2 treatment groups: calves receiving (twice daily) a solution containing 500 mg of SB-300 added to the whole milk for the first 15 d of life (SB-300, n = 20) or a control group receiving sterile water added to whole milk for the same period (CTR, n = 20). Treatment solutions had a total volume of 10 mL per treatment. Data regarding fecal dry matter were collected to precisely measure water content in fecal samples and to define diarrhea events; the SB-300 group had significantly increased fecal dry matter during the study period. Additionally, significantly fewer events of diarrhea were observed for calves in the SB-300 group (16.9%) compared with calves in the CTR group (46.5%). Dehydration status was evaluated and treated accordingly; calves with moderate dehydration were offered oral electrolytes, and calves with severe dehydration were rescued with intravenous fluid therapy. Calves in the SB-300 group had fewer intravenous fluid therapies administered during the study period (1.6%) compared with the CTR group (3.1%). Overall fluid therapy administered (oral electrolytes plus intravenous fluids) was significantly higher for the CTR group (9.2%) compared with the SB-300 group (6.1%) during the study period. No differences in milk consumption, calf starter intake, or weight gain were observed between treatment groups. A single time increase in Bifidobacterium was observed on d 20 of life for the SB-300 group; otherwise, no differences in fecal microbiome profile were detected between treatment groups. These results suggest that 500 mg of SB-300 added to the milk for 15 d can reduce the incidence of diarrhea and reduce severe dehydration in milk-fed calves.