Rams with poor feed efficiency are highly responsive to an exogenous adrenocorticotropin hormone (ACTH) challenge

An animal's response to a stressor is to increase metabolic rate, and thus energy consumption through the activation of the hypothalamic-pituitary-adrenal axis. Changes to energy use by an animal are likely to influence the efficiency with which it is utilised. In this study, we tested the hypothesis that less efficient sheep are more responsive to exogenous administration of adrenocorticotropin hormone. This was done by firstly determining the appropriate dose (0.4, 1.6 or 6.4microg/kg LW) and peak serum cortisol response time (45min) to exogenous administration of adrenocorticotropin hormone in a pilot study (n=3 sheep). Following this, adrenocorticotropin hormone (2.0microg/kg LW) stimulated cortisol levels were measured in a larger group of sheep (n=50) of known feed efficiency (feed conversion ratio and residual feed intake values). Less efficient sheep (more positive residual feed intake values) were found to have a greater (P<0.001) increase in cortisol concentration in comparison to more efficient animals. Those sheep which had higher levels of cortisol also had a greater proportion (P<0.001) of fat tissue. These data clearly demonstrated that efficiency of energy use, when measured as residual feed intake, is significantly related to an animal's stress response. These findings have important implications for understanding the physiological mechanisms underpinning efficiency of energy use, and may be useful in successfully identifying animals which are superior in terms of feed efficiency.     

Lactation efficiency as a result of body composition dynamics and feed intake in sows

Through genetic selection and improvement of environment, litter size of sows increases. Increased energy requirement during lactation, increases the risk of excessive mobilization from body stores, with detrimental effects on reproductive performance. Feed intake capacity tends to decrease due to selection towards leaner pigs with a lower feed conversion ratio. However, to facilitate sows to wean large litters extra feed intake, or even better, a higher feed efficiency during lactation would be favourable. The objective of the present study was to describe the dynamics of body composition of sows and piglets during lactation, and to relate these traits to a newly introduced trait called “lactation efficiency”. Energy metabolism of lactating sows was described, based on on-farm observations of weight and backfat of sows before parturition and at weaning, weight of piglets at birth and at weaning and feed intake of sows during lactation. “Lactation efficiency” was defined as energy efficiency of sows, and calculated for individual sows at two different farms. The average lactation efficiency was 68% and 65% for both farms; meaning that 68 and 65% of the metabolisable energy through feed intake or mobilization from body stores, above maintenance of the sow (input), was used for piglet growth and piglet maintenance (output). The association between lactation efficiency and other reproductive traits was studied by estimating the correlations within farms. Sows with a higher lactation efficiency showed lower feed intake (r = − 0.27 and r = − 0.35 for both farms respectively) and smaller fat losses (r = − 0.34 and r = − 0.29, respectively). The energy output of efficient sows was slightly higher (r = 0.23 and r = 0.30). The more efficient sows were the better mothers, as mortality of their piglets was lower (r = − 0.12 and r = − 0.16), piglet growth rate was higher (r = 0.16 and r = 0.23), and at weaning their litters were less variable (r = − 0.08; only available at one farm). Results were remarkably similar for the two farms, despite different feeding strategies. Extra input, by means of feed intake or mobilization from body stores generated extra output by means of litter weight at weaning. This experiment demonstrated that an accurate recording of energy metabolism and relevant reproduction traits with little intervention is possible on commercial farms.     

A review of feed efficiency in swine: biology and application

Feed efficiency represents the cumulative efficiency with which the pig utilizes dietary nutrients for maintenance, lean gain and lipid accretion. It is closely linked with energy metabolism, as the oxidation of carbon-containing components in the feed drive all metabolic processes. While much is known about nutrient utilization and tissue metabolism, blending these subjects into a discussion on feed efficiency has proven to be difficult. For example, while increasing dietary energy concentration will almost certainly increase feed efficiency, the correlation between dietary energy concentration and feed efficiency is surprisingly low. This is likely due to the plethora of non-dietary factors that impact feed efficiency, such as the environment and health as well as individual variation in maintenance requirements, body composition and body weight.Nonetheless, a deeper understanding of feed efficiency is critical at many levels. To individual farms, it impacts profitability. To the pork industry, it represents its competitive position against other protein sources. To food economists, it means less demand on global feed resources. There are environmental and other societal implications as well.Interestingly, feed efficiency is not always reported simply as a ratio of body weight gain to feed consumed. This review will explain why this arithmetic calculation, as simple as it initially seems, and as universally applied as it is in science and commerce, can often be misleading due to errors inherent in recording of both weight gain and feed intake.This review discusses the importance of feed efficiency, the manner in which it can be measured and reported, its basis in biology and approaches to its improvement. It concludes with a summary of findings and recommendations for future efforts.     

Assessing the accuracy of modelling weight gain of cattle using feed efficiency data

Different methods of estimating weight gain were compared for accuracy and utility, using the amount of error variation from fitting the residual feed intake (RFI) model. Data were collected on 1481 cattle of temperate and tropically adapted breeds, feedlot-finished for the domestic (liveweight 400 kg), Korean (520 kg), or Japanese (steers only; 600 kg) markets. Cattle were tested in 36 groups over 4 years. The aim was to estimate weight gain over the period feed intake was measured, which was at least 49 days and averaged 63 days, including time for animals to adapt to the automatic feeding system. The different estimates were derived from linear and quadratic regressions of weight over time fitted to: F1) all weighings in the feedlot and F2) all weighings in the feedlot excluding atypical records in the first few weeks following feedlot entry. More complex linear and quadratic models were also fitted to weighings when feed intake was being measured, using the amount of feed eaten on the day of weighing, and previous days, to adjust for gut fill. Finally, a random regression model including general trends in the growth of each animal and short term measurement error was fitted to dataset F2 to estimate weight gain for the period feed intake was measured.The RFI equation: feed intake=intercept(s)+β_w*mean(weight^0.73)+β_g*weight gain+error (i.e. RFI) was fitted using the different weight gain estimates. Based on mean squared errors from fitting this equation, longer measurement periods generally resulted in more accurate estimates of weight gain. The increased accuracy from using all weight measurements in the feedlot outweighed the loss from not measuring over the desired time interval—i.e. the period for which feed intake was measured.     

Relationship between body measurements,metabolic hormones,metabolites and residual feed intake in performancetested pedigree beef bulls

The objective of this study was to examine the relationship between easily measured, potential physiological and physical indicators of feed efficiency including metabolic hormones, metabolites, ultrasonic muscle and fat measures with performance and efficiency traits in performance tested pedigree beef bulls (n = 302; initial bodyweight 493 (SD = 64) kg). Animals were offered a high energy concentrate ad libitum plus 1.5 kg fresh weight grass hay daily and individual feed intake was measured for 70 days. Blood samples were collected by coccygeal venipuncture at the start and end of the performance test period and analysed for plasma concentrations of IGF-I, insulin, leptin and various metabolites. Similarly, ultrasonic muscle and fat depths were measured at the start and end of the test period. Residual feed intake (RFI) was computed for each animal as the residuals from a multiple regression model regressing dry matter intake (DMI) on average daily gain (ADG) and mid-test BW^0.75 (MWT). Overall ADG, DMI, feed:gain (F:G) and RFI were 1.91 (SD = 0.29), 10.10 (SD = 1.31), 5.37 (SD = 0.84) and 0.00 (SD = 0.78), respectively. Residual feed intake was strongly correlated with DMI (r = 0.67) and moderately correlated with F:G (r = 0.40). Moderate positive correlations ranging from 0.3 to 0.6 were estimated between ultrasonic measures of final fat and muscle depth and their respective gains over the test period with DMI, ADG and RFI. There was no evidence of a strong association between any of the plasma analytes measured and RFI at either sampling times. However, end of test insulin was negatively correlated (r = − 0.14) with RFI. Final IGF-I concentration was negatively associated with DMI (r = − 0.14) and F:G (r = − 0.15). End of test circulating leptin concentration was positively correlated with DMI (r = 0.14) and F:G (r = 0.15). Plasma glucose concentration at the end of test was negatively related to DMI (r = − 0.21) and F:G (r = − 0.21). A positive relationship was observed between end of test plasma urea concentration and DMI (r = 0.30). Overall, the correlation coefficient estimates between the potential blood markers and measures of intake, performance and efficiency were weak and generally not different from zero. This suggests that it is unlikely that measurement of these metabolic indicators, per se, will be useful in the early identification of feed efficient animals.     

提高猪饲料效率的测定与选择

为提高猪饲料效率的选择,本试验测定一些与猪饲料效率相关的生产性状并进行遗传评估。方法：测定60头军牧1号白猪后备公猪的采食量、体增重、背膘厚等生产性状,用猪剩余采食量（RFI）和饲料转化率（FCR）作为评价饲料效率的两个指标,并对其遗传参数进行评估。结果：测定期内军牧1号公猪群体FCR均值为2．61,RFI的标准差为77．52。RFI与FCR的遗传力分别是0．35、0．33,RFI与ADFI（日采食量）、ADG（日增重）、BF（背膘厚）的遗传相关分别是0．89、0．12、-0．05,FCR与ADFI、ADG、BF的遗传相关分别是0．55、-0．65、-0．11。结论：军牧1号白猪品种内饲料效率存在较大的遗传差异,由于RFI与ADG遗传相关很低,因此用RFI作为选择性状可有效提高猪的饲料效率。     

On the relationships between glucocorticoids and feed efficiency in beef cattle

Improvement in the utilization of feed in livestock is an important target of breeding and nutritional programs. Recent evidence indicates a potential association between feed efficiency and fecal cortisol metabolites, which could eventually be used as an indirect assessment of this trait. This evidence is more comprehensively evaluated in here with samples for plasma cortisol (PC; ng/ml) and fecal cortisol metabolites (FCM; ng/ml) collected more often during the entire finishing phase in beef steers. Individual daily feed intake of 112 steers fed a high-moisture corn-based and haylage diet was measured over 168 d. Body weight, blood and fecal samples were collected every 14 d and ultrasound measures of backfat thickness and longissimus muscle area were taken every 28 d. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F:G) and residual feed intake (RFI). At the end of the feedlot phase, steers were ranked according to RFI and samples were analyzed for PC and FCM from the 32 steers with greatest and 32 steers with lowest feed efficiency. In addition, a sub-group of 12 steers from each of these two groups with divergent feed efficiency were subjected to hourly blood sampling for 24 h. Less efficient steers had greater DMI, F:G and consumed 1.5 kg/d more DMI (P<0.05) than steers with improved feed efficiency. No differences (P>0.10) in PC over the 12 biweekly sampling periods between steers with divergent feed efficiency were observed. However, a trend toward significance between 19:00 and 02:00 h over the hourly sampling evaluation was noticed, with the sub-group of more feed efficient steers presenting higher levels of PC in this period of the day (P=0.08). On the other hand, FCM levels displayed a distinct pattern between RFI groups over the biweekly sampling period, with more efficient cattle presenting greater levels of these metabolites (P<0.05). This study reinforces the positive association between improved feed efficiency and FCM levels over the finishing phase; and the lack of association between feed efficiency and PC when single samples are collected every two weeks through a single jugular venipuncture performed after handling the cattle for sampling. Further studies to develop sampling protocols for assessing FCM as an indicator trait for feed efficiency are warranted, as well as, studies to understand the role of endogenous glucocorticoids in the performance of the bovine.     

Feed intake,digestibility, body weight and carcass parameters of Afar rams fed tef (Eragrostis tef) straw supplemented with graded levels of concentrate mix

The experiment was conducted at Alamata Agricultural Research Center, Ethiopia using 20 Afar rams with an initial body weight (BW) of 18.2 ± 1.76 (mean ± SD) kg. The objectives were to study the effect of supplementation with concentrate mix consisting of wheat bran (WB), noug seed cake (NSC) and sesame seed cake (SSC) at the ratio of 2:1:1 on dry matter (DM) basis, respectively on feed intake, digestibility, BW gain and carcass parameters of Afar rams fed tef (Eragrostis tef) straw basal diet. The experiment was arranged with four treatments and five replications in a randomized complete block design. The treatments included feeding sole tef straw (T1, control), and daily supplementation with the concentrate mix offered at 150 (T2, low), 250 (T3, medium) and 350 (T4, high) g DM per head. Total DM intake, crude protein (CP) digestibility, daily BW gain (P < 0.001), DM and organic matter (OM) digestibility, and carcass parameters (P < 0.05) were higher in the supplemented than in the control treatment. Intake of tef straw reduced as the level of supplementation increased, whereas the contrary was true for CP intake. Performance in carcass parameters was better for the medium compared to the low level of concentrate mix supplementation. Moreover, the medium level of supplementation did not substitute tef straw intake. Therefore, it is concluded that the medium level of concentrate mix supplement maintained the utilization of the roughage feed and resulted in better carcass parameters.     

Performance and ruminal protozoa in lambs with chromium supplementation

The effects of chromium picolinate (CrPic) oral supplementation on the performance and ruminal protozoa population in sheep was investigated. Twenty-four male lambs were treated with four different levels of CrPic: placebo, 0.250, 0.375 and 0.500 mg of chromium/animal/day during 84 days. The base ration was Panicum maximum cv Massai hay and concentrate. Feed intake was measured three times a week. Lambs were weighed every 2 weeks. Ruminal content was sampled five times during the trial to quantify ruminal protozoa. No difference (p > 0.05) between treatments was recorded for any parameter measured: initial and final mean body weight, dry matter intake, daily gain and total body weight gain. There was a negative linear relationship between Cr supplementation and protozoa count (p = 0.0013) with no additional decrease when CrPic supplemental levels were higher than 0.375 mg/day. Therefore, Cr supplementation must be carried out carefully and more studies need to address stressed animals or possible toxic effects of Cr in the animal itself or to the ruminal protozoa population.     

日粮中添加调味剂对围产期奶牛采食量、产后体重和体况评分的影响

选用32头干奶后期荷斯坦牛,按照年龄、体重、胎次和上个周期产奶量相同或相近的原则,随机分成4个处理组,研究在日粮中添加草香味调味剂、焦糖味调味剂和果香味调味剂（添加比例100g/t TMR日粮）,对奶牛采食量、产后体重恢复和体况评分的影响。结果表明,在日粮中添加调味剂对围产期奶牛产前和产后的干物质采食量有提高的趋势,其中产前日粮添加调味剂A（草香味）和调味剂B（焦糖味）可以显著提高奶牛的干物质采食量（P〈0.05）;在日粮中添加调味剂对围产期奶牛产后体重的恢复有促进作用,其中添加调味剂B（焦糖味）组奶牛在产后28天和42天的测定值显示,可以显著影响围产期奶牛产后的体重恢复（P〈0.05）;在日粮中添加调味剂对围产期奶牛产后体况的恢复有促进作用,其中在奶牛产后14天的测定值显示,添加调味剂B（焦糖味）可以显著改善奶牛的体况（P〈0.05）;在产后28天,添加调味剂B（焦糖味）和调味剂C（果香味）可以显著改善奶牛的体况（P〈0.05）;在产后42天,添加调味剂A（草香味）、调味剂B（焦糖味）和调味剂C（果香味）都可以显著改善奶牛的体况（P〈0.05）。即在围产期奶牛日粮中添加不同风味的调味剂,都可以提高奶牛的干物质采食量,促进奶牛产后体重和体况的恢复,其中焦糖味调味剂的效果最为明显。     

Effect of selection for growth on normal and reduced protein diets on weight gain, feed intake, feed efficiency and body composition in mice

Mice selected for weight gain from 3 to 9 weeks of age on a normal (N) protein diet containing 19.3% protein and a reduced (R) protein diet with 5.1% protein were reared on both diets in generations 7 and 9. The lines NH, NC, NL, RH, RC and RL (H, high; C, control; L, low) were tested for weight gain on diet N and R and for feed intake and feed efficiency on diet N in generation 7. In generation 9, the lines were tested for body composition traits (fat, protein and water percentage) at 3, 6, 9 and 12 weeks of age on both diets. A significant (p < 0.0001) genotype × environment interaction for growth rate was observed in generation 7. Weight gain at both the protein levels was best improved by selection at the protein level itself. Furthermore, the ranking of the lines on diet N was similar for weight gain, feed intake and feed efficiency. In generation 9 at 9 weeks of age, the ranking of the lines for fat percentage was equal to the ranking for weight gain in generation 7 on both test‐diets. The association between weight gain and protein or water percentage was less pronounced, particularly on diet R. These results suggest that the largest genetic improvement in growth rate is obtained when the protein content of the feed is the same in selection and production. However, when selection is carried out in one environment while the animals have to perform under conditions with varying nutrient protein contents, selection in an inferior environment may be advantageous.     

绍兴鸭剩余采食量与部分生产性能及蛋品质的相关性分析

本实验旨在探讨绍兴鸭剩余采食量(RFI)与生产性能及蛋品质之间的关系。测定300只绍兴鸭410~470日龄的采食量、体重、平均蛋重、蛋品质,计算出剩余采食量与料蛋比,并分析剩余采食量与生产性能及蛋品质的相关性。结果显示:绍兴鸭平均采食量、平均蛋重、体重、体增重、料蛋比、剩余采食量分别为198.8 g/d、73.0 g、1500.9 g、2.5 g/d、2.7、3.5 g/d;低剩余采食量组的剩余采食量、采食量以及料蛋比极显著低于高剩余采食量组;相关性分析表明,剩余采食量与采食量和料蛋比呈极显著正相关(P<0.01);采食量与平均蛋重、体重呈极显著正相关(P<0.01),与料蛋比呈极显著负相关(P<0.01),与体增重呈显著正相关性(P<0.05);蛋品质分析结果表明,高剩余采食量组仅蛋黄色泽水平显著高于低剩余采食量组;相关性分析表明,剩余采食量与蛋品质各指标间均无显著相关性。本试验结果表明,以剩余采食量为蛋鸭选育指标是可行的,且选育低剩余采食量的鸭子能显著降低采食量,提高饲料效率,且不改变产蛋重及蛋品质。     

玉米秸处理方法与替换干草水平对绵羊瘤胃发酵与采食量的影响

选用12只安装有永久性瘤胃瘘管、十二指肠近端瘘管的内蒙古半细毛羯羊。在1 1M饲喂水平下,研究不同处理的玉米秸对生长肥育羊瘤胃发酵和采食量的影响,试验结果表明:不同处理的玉米秸替换干草的水平,对瘤胃pH值无显著影响(P>0 05)。与未处理组(C组)比较,兴牧宝处理组(XT)组NH3 N浓度较低,而氨化处理组(AT组)的较高(P<0 05)。XT组和AT组的微生物蛋白(MCP)产量均明显高于C组(P<0 05),分别提高了33 67%和25 68%。随着玉米秸替换干草水平的增加,NH3 N浓度、MCP的合成及乙酸、丙酸和丁酸的浓度均显著降低(P<0 05)。XT组的丙酸浓度高于C组和AT组(P<0 05)。XT组、AT组采食量分别提高了4 90%和3 75%。玉米秸替换干草的适宜比例为30%～60%(占日粮干物质比例的21%～42%)。     

Adiponectin and leptin are related to fat mass in horses

Plasma concentrations of adiponectin and leptin were measured in 23 mature Standardbred mares (age: 10 ± 3 years) and 12 weanling fillies (10 Quarter Horse/Belgian crossbreds and two Quarter Horses; aged: 4 ± 3 months) to test the hypothesis that adipocytokines are proportional to adiposity in horses. Rump fat thickness was measured using B-mode ultrasound and percent body fat (% fat) calculated using a published formula for the estimation of fatness in horses. Plasma adiponectin and leptin were determined using radioimmunoassay. In the absence of purified equine adiponectin or leptin, results were expressed as human equivalents (HE) of immunoreactive (ir) adipocytokines.Plasma ir-leptin HE concentration was positively correlated (r = 0.543; P < 0.001) with percent body fat and (r = 0.556; P < 0.001) to fat mass in all horses. The plasma ir-leptin HE concentration was lower (P = 0.03) in weanlings (1.90 ± 0.34 ng/mL HE) than in mature mares (3.47 ± 0.50 ng/mL HE). The ratio of ir-adiponectin HE to ir-leptin HE was negatively correlated (r = −0.621; P < 0.001) to percent fat and (r = −631; P < 0.001) to fat mass in all horses. The ratio of ir-adiponectin HE to ir-leptin HE was higher (P < 0.001) in weanlings (3.04 ± 0.51) than mature mares (1.03 ± 0.13). These data suggest that leptin is proportional while adiponectin is inversely proportional to adiposity in horses.     

Effect of breed on body composition and comparison between various methods to estimate body composition in dogs

The objectives of this clinical study were firstly, to assess the effects of breed/genetic group on body composition in dogs using Dual-X-ray absorptiometry (DEXA) as the reference method and secondly, to check, in clinical field conditions, if methods easy to apply in veterinary practice [bioelectrical impedance (BIA), morphometric equations, body condition score and body mass index] can give similar body composition results to DEXA results, using canine breeds with very different genetic and morphologic backgrounds. 19 dogs from 6 breeds with different genetic origin were used. Results showed that breed differences exist regarding body composition in dogs. Body condition score and morphometric equation should be developed by breed or by groups of breeds for an accurate estimation of body composition of the various breeds of dogs with a different genetic background or morphology. Any of the other tested methodologies (BIA or morphometric equations) gave results in agreement with DEXA value, when dogs with different genetic background and morphologic characteristics are used, but BIA, eventually in combination with morphometric measurements, could be a method to develop to estimate fat-free mass in dogs of different breeds.     

Effects of a high-protein, low-energy diet in finishing lambs: 2. Weight change, organ mass, body composition, carcass traits, fatty acid composition of lean and adipose tissue, and taste panel evaluation

An experiment was conducted to evaluate the effects of a high protein – low energy diet on body composition of feedlot lambs The objective was to assess the capability of such a diet to reduce body fat while preserving lean body mass. Three dietary regimens were compared: a typical feedlot diet (CON), barley straw at libitum (STR), and barley straw supplemented with fish meal (SFM). The latter two diets caused an energy deficit in the experimental animals. Significant treatment effects on mass of metabolic organs, body composition, and carcass data were observed. Conventional analysis of sensory data and fatty acid profiles of adipose and muscle tissue identified few significant dietary effects, yet discriminant analysis clearly separated all treatment groups. It was concluded that protein supplementation of ruminants in the catabolic state does not conserve protein mass. Given the high cost of protein supplementation, the post hoc modification of body composition of feedlot lambs is not a viable option. It is suggested that the production of feedlot lambs with a desirable degree of fatness should employ a feeding strategy dynamically adapted to the changes in protein – energy balance required by the growing ruminant.     

Feed preference and feeding behaviours in grower broilers fed diets containing wheat naturally contaminated with fusarium mycotoxins

1. Two trials were conducted to determine the effect of feeding diets contaminated with fusarium mycotoxins (primarily deoxynivalenol (DON)) on broiler chicken feed preference, feeding behaviour and growth performance.

2. A total of 120 male Ross 308 chicks (4 birds/cage, 30 cages) were fed a common corn-based starter diet from 1 to 20 d of age. At 21 d, 15 cages were randomly assigned to the feed preference trial or a feeding behaviour trial. Three wheat-based experimental diets (0.14, 2.27 and 5.84 mg/kg DON) were prepared with a clean wheat and a naturally contaminated wheat. Broilers were ad libitum fed the experimental diets during 21–27 d.

3. In the preference trial, each cage’s feeder was split into two equal-sized compartments so birds were provided a choice of two diets (control vs. low, control vs. high and low vs. high DON). In the feeding behaviour trial, diets were randomly assigned to 15 cages (5 cages/diet). Feeding and drinking behaviour was recorded for 1 h before and after the dark period and 1-h period at 9 h after the light was turned on (middle of day). Growth performance was assessed at 27 d.

4. In the preference trial, broilers preferred the control diet over low (93.0 vs. 66.1 g/d, P < 0.01) and high (104.4 vs. 50.4 g/d, P < 0.01) DON diets. At all three timepoints, where behaviour was recorded, birds offered the DON diets spent more time at the feeder compared to birds provided control diets (P < 0.05). Control birds had lower feed to gain ratio (1.65) than birds fed low (1.82) and high (1.94) DON diets (P < 0.01).

5. It is clear that broilers are sensitive to the presence of fusarium mycotoxins and that moderate levels of DON negatively affect feed preference and growth performance when fed during the grower period.     

Effects of season and body condition on appetite, body mass and body composition in ad libitum fed pony mares

Changes in appetite, body mass (BM), body condition score (BCS), direct (ultrasonographic) and indirect (deuterium oxide dilution technique) measures of body fat were monitored in Welsh Mountain pony mares (n = 11, 5–19 years of age) offered ad libitum access to a complete diet (gross energy 16.9 ± 0.07 MJ/kg dry matter) for 12 weeks during summer (n = 6; 246 ± 20 kg) and winter (n = 5; 219 ± 21 kg). At the outset, each group comprised two thin (BCS 1–3/9), moderate (BCS 4–6/9) and obese (BCS 7–9/9) animals.For ponies that were non-obese at the outset, BM was gained more rapidly (P = 0.001) in summer (0.8 ± 0.1 kg/day) than winter (0.6 ± 0.0 kg/day). This was associated with a seasonal increase in dry matter intake (DMI) which became maximal (summer, 4.6 ± 0.3% BM as DMI/day; winter, 3.5 ± 0.1% BM as DMI/day) during the second month. The appetite of the obese ponies was half that reported for non-obese animals in the summer and BM remained constant irrespective of season.Body ‘fatness’ increased progressively for non-obese but not obese ponies. Body fat content was exponentially associated with increasing BCS but BCSs >6 were not useful indicators of actual body fat. Endogenous circannual mechanisms to suppress winter weight gain were insufficient to prevent the development of obesity in ad libitum fed ponies.     

Reduction in channel catfish hepatic growth hormone receptor expression in response to food deprivation and exogenous cortisol

The objective of this study was to assess the effects of food deprivation and exogenous cortisol administration on somatic growth of channel catfish, Ictalurus punctatus, and examine the resultant changes in circulating insulin-like growth factor-I (IGF-I) concentrations and growth hormone receptor (GHR) gene expression. Integral to this objective, we report the isolation, sequence, and characterization of channel catfish GHR. Sequence analysis and characterization results indicate sequence identity and tissue distribution similar to GHRs in other teleost fish and several functional characteristics conserved in known vertebrate GHRs. The effects of food deprivation and dietary exogenous cortisol administration were assessed as part of a 4-week study. Growth was significantly reduced after 4 weeks in cortisol-fed fish compared to fed-control fish, and fasting resulted in weight loss. At the end of the 4-week study, both IGF-I plasma concentrations and hepatic GHR mRNA abundance were significantly reduced in fasted and cortisol-fed catfish. Levels of hepatic GHR mRNA were positively correlated to circulating IGF-I levels. These results suggest that a reduction in hepatic GHR gene expression might serve as a mechanism for the reduction of circulating IGF-I and growth in channel catfish during periods of food deprivation and stress.     

Feed intake,digestibility and body weight change in Farta sheep fed hay supplemented with rice bran and/or noug seed (<Emphasis Type="Italic">Guizotia abyssinica</Emphasis>) meal

The study was conducted to determine the effect of supplementation with rice bran (RB) and /or noug seed (Guizotia abyssinica) meal (NSM) on feed intake, digestibility, and body weight (BW) change in hay based feeding of Farta sheep. Twenty five yearling Farta rams with a mean initial BW of 19.23 ± 0.28 kg were used in randomized complete block design arranged into five blocks of five animals. The five dietary treatments that consisted of hay alone (T₁), hay + RB (T₂), hay + mixture of RB and NSM at a ratio of 1:2 (T₃), hay + mixture of RB and NSM at a ratio of 2:1 (T₄) and hay + NSM (T₅) were randomly assigned to each sheep within a block. The supplements were daily offered at 300 g dry matter (DM) head⁻¹ in two equal parts at 800 and 1600 h. Supplementation improved the total DM and acid detergent fiber (ADF) intake (P < 0.05), organic matter (OM) intake (P < 0.01), crude protein (CP) intake (P < 0.001). The apparent digestibility of DM in T₅ was higher (P < 0.05) than in T₁ and T₂ and that of T₄ was also higher (P < 0.05) than in T₁. The apparent digestibility of CP in T₅ and T₄ were higher (P < 0.001) than in T₁ and T₂ and that of T₃ and T₂ were also higher (P < 0.001) than for T₁. The BW gain of experimental sheep was improved (P < 0.01) by supplementation with NSC (T₅) and/or its mixtures with RB (T₃ and T₄). The results of the study showed that supplementation with either of both mixtures of NSM and RB at 43% of total DM intake promoted better feed intake, digestibility and BW gain in Farta sheep.