Impact of a high-fibre diet on genetic parameters of production traits in growing pigs

The use of diets with increased fibre content from alternative feedstuffs less digestible for pigs is a solution considered to limit the impact of increased feed costs on pig production. This study aimed at determining the impact of an alternative diet on genetic parameters for growth, feed efficiency, carcass composition and meat quality traits. A total of 783 Large White pigs were fed a high-fibre (HF) diet and 880 of their sibs were fed a conventional (CO) cereal-based diet. Individual daily feed intake, average daily gain, feed conversion ratio and residual feed intake were recorded as well as lean meat percentage (LMP), carcass yield (CY) and meat quality traits. Pigs fed the CO diet had better performances for growth and feed efficiency than pigs fed the HF diet. They also had lower LMP and higher CY. In addition, pigs fed the CO diet had lower loin percentage and ham percentage and higher backfat percentage. No differences were observed in meat quality traits between diets, except for a* and b* values. For all traits, the genetic variances and heritability were not different between diets. Genetic correlations for traits between diets ranged between 0.80 ± 0.13 and 0.99 ± not estimable, and none were significantly different from 0.99, except for LMP. Thus, traits in both diets were considered as mainly affected by similar sets of genes in the two diets. A genetic correlation lower than 0.80 would justify redesigning the breeding scheme; however, some genetic correlations did not differ significantly from 0.80 either. Therefore, larger populations are needed for a more definitive answer regarding the design of the breeding scheme. To further evaluate selection strategies, a production index was computed within diets for the 29 sires with estimated breeding value reliability higher than 0.35. The rank correlation between indices estimated in the CO and in the HF diet was 0.72. Altogether, we concluded that limited interaction between feed and genetics could be evidenced, and based on these results there is no need to change pig selection schemes to adapt to the future increased use of alternative feedstuffs in production farms.     

Dietary protein requirement of juvenile triangular bream Megalobrama terminalis (Richardson, 1846)

A 10‐week feeding trial was conducted to determine the dietary protein requirement of juvenile triangular bream (Megalobrama terminalis). Five semi‐purified diets (white fishmeal as a protein source) were formulated with five crude protein (CP) levels (26.30%, 32.94%, 38.33%, 44.18% and 50.09%; diets P1–P5). Each diet was fed to triplicate groups (20 per fish replicate, initially weighing 1.30 ± 0.02 g). The following parameters were measured to evaluate the effects of different CP levels: weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), daily feed intake (DFI), viscerosomatic index (VSI), hepatosomatic index (HSI), intraperitoneal fat ratio (IPF), lipid retention (LR), liver glycogen content and plasma triglyceride level. The results of the feeding trial showed that WG, SGR and FE were significantly enhanced by an increasing dietary protein level of up to 44.18%, but there were no significant differences in protein levels from 44.18% to 50.09%. The PER and DFI showed a decreasing trend with increasing dietary CP levels. The VSI and HSI were not significantly affected by the different treatments, whereas the IPF increased significantly with decreasing CP levels. The highest LR value, liver glycogen value and triglyceride level in plasma were observed in fish fed the lowest CP diet (P1). Based on the WG and FE, this study suggests an optimum dietary protein level for M. terminalis of 44.18%.     

Effects of feeding low fishmeal diets with increasing soybean meal levels on growth,gut histology and plasma biochemistry of sea bass

The aquaculture industry depends upon the development of sustainable protein sources to replace fishmeal (FM) in aquafeeds and the products derived from soybeans are some of the most studied plant feedstuffs. A key area of investigation for continuing to improve modern aquafeeds includes the evaluation of varying proportions and combinations of plant ingredients to identify mixtures that are more efficiently utilized by the fish. This study investigated the effects of increasing soybean meal (SBM) by replacing a mix of plant ingredients in low FM (20%) diets on growth, blood biochemistry profile and gut histology on European sea bass. Five isonitrogenous and isolipidic experimental diets were formulated: four diets containing increasing SBM levels (0, 10, 20 and 30%; 0SBM, 10SBM, 20SBM and 30SBM, respectively) with a low content of FM (20%) and one control diet (0% SBM; 35% FM). Diets containing SBM brought to comparable performance and protein utilization, while 0SBM had negative impact on feed conversion rate and protein utilization. Blood parameters suggested an optimal nutritional status under all feeding treatments, even though slightly decreased values were reported at increasing dietary SBM. Histology examination did not show any changes indicative of soy-induced enteritis. We can conclude that for European sea bass: (i) different blends of plant protein did not affect feed intake despite the 20% FM dietary level; (ii) the inclusion of SBM maintains optimal growth and feed utilization in low FM diets; (iii) blood biochemistry profile showed a good nutritional status under all feeding regimes; (iv) no evidence of soy-induced enteritis was reported in any group fed low FM diets. For formulation of practical diets in on-growing of European sea bass, SBM up to 30% can be successfully incorporated into feeds containing low FM inclusion.     

四种植物蛋白对中华绒螯蟹幼蟹生长性能、氨基酸沉积率和抗氧化酶活性的影响

为了筛选适宜于养殖中华绒螯蟹幼蟹的饲料植物蛋白源,探究不同植物蛋白源饲料对幼蟹生长性能、氨基酸沉积率和抗氧化性能等方面的影响,以50%的鱼粉配制基础饲料（记为FM）,分别采用30.5%发酵豆粕、32.5%豆粕、28%棉粕和39%菜粕替代基础饲料中鱼粉总量的50%,配制成4种等氮等能的饲料（分别记为FSBM、SBM、CSM和RSM）,投喂初始体重为（0.249±0.003）g的中华绒螯蟹幼蟹8周。结果表明:（1）与FM组相比,FSBM、SBM和CSM组的增重率、特定生长率、饲料系数、蛋白质效率和蛋白质沉积率均没有显著性差异;RSM组的增重率与FM组相比差异不显著（P>0.05）,但显著低于SBM组（P < 0.05）,而其饲料系数则显著高于FM、FSBM及SBM组（P < 0.05）,蛋白质效率显著低于其他各组（P < 0.05）,蛋白质沉积率显著低于SBM和CSM组（P < 0.05）。（2）不同植物蛋白组的总必需氨基酸沉积率和FM组相比差异不显著（P>0.05）,而RSM组总必需氨基酸沉积率显著低于FSBM和CSM组（P < 0.05）。（3）与FM组相比,不同植物蛋白组蟹的血清和肝胰腺中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-PX）活性和肝胰腺丙二醛（MDA）含量并没有显著的影响,而RSM组血清丙二醛（MDA）含量显著的高于其他各组（P < 0.05）。结果表明,在幼蟹饲料中,豆粕、发酵豆粕和棉粕替代基础配方中鱼粉的50%后并未对幼蟹的生长性能、氨基酸沉积率及抗氧化能力造成负面的影响,发酵豆粕、豆粕和棉粕可以作为替代鱼粉的适宜蛋白源,且添加水平约在30%左右。菜粕替代后降低了饲料的利用和氨基酸沉积效率,这可能是由于菜粕的蛋白质消化率低、含有相应的抗营养因子和添加水平过高所致,建议使用前应适当进行脱毒处理,并与或和其他植物蛋白配伍使用。     

The effects of feeding time and time-restricted feeding on the fattening traits of White Roman geese

This study comprises two trials that investigated the effects of feeding time and time-restricted feeding on the fattening traits and plasma metabolite levels of White Roman geese. In Trial I, 24 geese aged 8 weeks of each sex were allowed free access to a fattening diet for 1 h either in the morning (morning-feeding group) or afternoon (afternoon-feeding group). At 12 weeks of age, blood samples were collected hourly for 4 h, beginning 1 h after feeding to determine the plasma levels of glucose, triacylglycerols and uric acid. The results showed a lower (P<0.05) daily feed intake (DFI) and daily gain (DG) and higher (P<0.05) feed efficiency (FE) for the morning-feeding group compared with those of the afternoon-feeding group. In addition, the postprandial plasma levels of glucose, triacylglycerols and uric acid did not differ (P>0.05) between groups. In Trial II, 12 geese aged 8 weeks of each sex were randomly assigned to either the ad libitum feeding group (control group) or time-restricted feeding group (restricted group). The geese in the control group were fed a fattening diet ad libitum, whereas those in the restricted group were allowed access to the diet for 2 h every morning. All geese were killed at 13 weeks of age and their carcass traits were evaluated. The results showed a lower DFI and DG and higher FE for the restricted group compared with those of the control group (P<0.05). In addition, the restricted group exhibited lower visceral and abdominal fat and higher empty digestive tract and liver weights than those of the control group (P<0.05). The results showed that time-restricted feeding in the morning resulted in superior DG and FE compared with feeding in the afternoon. Moreover, time-restricted feeding implemented in the morning during the fattening period reduced DFI and increased FE in geese compared with ad libitum feeding.     

Haemato-immunological and growth response of mirror carp (Cyprinus carpio) fed a tropical earthworm meal in experimental diets

An investigation was conducted to evaluate the effect of feeding a tropical earthworm meal (Perionyx escavatus) on the haemato-immunological response and growth performance of mirror carp (Cyprinus carpio). Fish were fed diets for a total of 88 days, fishmeal served as the main protein source in the control diet. Two remaining diets consisted of fishmeal fixed at 33.65% provision of protein and the remaining 66.35% protein was provided by soybean meal (SBM diet) or P. excavatus meal (EW diet). Compared to control and SBM fed fish (7.69 ± 0.28 and 5.92 ± 0.31 g/dl, respectively), a significant increase in haemoglobin was measured in EW fed fish (9.57 ± 0.24 g/dl). Consequently significant elevations were also observed in mean corpuscular haemoglobin (MCH; 79.13 ± 4.59 pg) and mean corpuscular haemoglobin concentration (MCHC; 22.69 ± 0.54 pg) in EW fed fish. On the contrary, compared to control and SBM fed carp total leukocyte levels (2.72 ± 0.17 and 3.10 ± 0.17 × 10(4)/mm(3), respectively) were significantly decreased in the EW group (2.15 ± 0.14 × 10(4)/mm(3)). Moreover at day 14 and 21 post immunisation with bacterin isolated from Aeromonas hydrophila fish fed the EW diet displayed a significant reduction in respiratory burst activity (RBA) compared to control and SBM fed fish. After 60 days of feeding, fish fed EW diet showed a significant elevation in final body weight compared to fish fed a fishmeal based diet (control treatment) and fish fed a soybean meal based diet. Similar improvements were observed in feed utilisation efficiency. The present study shows that feeding P. excavatus meal to mirror carp decreases some aspects of the innate immune response, but at the same time gives rise to significant enhancement of growth and feed utilisation efficiency.     

Effects of balancing crystalline amino acids in diets containing heat-damaged soybean meal or distillers dried grains with solubles fed to weanling pigs

Two experiments were conducted to investigate if adjustments in diet formulations either based on total analysed amino acids or standardized ileal digestible (SID) amino acids may be used to eliminate negative effects of including heat-damaged soybean meal (SBM) or heat-damaged corn distillers dried grains with solubles (DDGS) in diets fed to weanling pigs. In Experiment 1, four corn–SBM diets were formulated. Diet 1 contained non-autoclaved SBM (315 g/kg), and this diet was formulated on the basis of analysed amino acid concentrations and using SID values from the AminoDat® 4.0 database. Diet 2 was similar to Diet 1 in terms of ingredient composition, except that the non-autoclaved SBM was replaced by autoclaved SBM at 1 : 1 (weight basis). Diet 3 was formulated using autoclaved SBM and amino acid inclusions in the diet were adjusted on the basis of analysed total amino acid concentrations in the autoclaved SBM and published SID values for non-autoclaved SBM (AminoDat® 4.0). Diet 4 also contained autoclaved SBM, but the formulation of this diet was adjusted on the basis of analysed amino acids in the autoclaved SBM and SID values that were adjusted according to the degree of heat damage in this source of SBM. Pigs (160; initial BW: 10.4 kg) were allotted to the four treatments with eight replicate pens per treatment in a randomized complete block design. Diets were fed to pigs for 21 days. The gain to feed ratio (G : F) was greater (P<0.05) for pigs fed Diet 1 compared with pigs fed the other diets and pigs fed Diet 4 had greater (P<0.05) G : F than pigs fed Diet 2. In Experiment 2, 144 pigs (initial BW: 9.9 kg) were allotted to four diets with eight replicate pens per diet. The four diets contained corn, SBM (85 g/kg) and DDGS (220 g/kg), and were formulated using the concepts described for Experiment 1, except that heat-damaged DDGS, but not heat-damaged SBM, was used in the diets. Pigs fed Diet 1 had greater (P<0.05) G : F than pigs fed Diet 2, but no differences were observed for G : F among pigs fed diets containing autoclaved DDGS. Results demonstrate that the negative effects of heat damage of SBM or DDGS may be ameliorated if the reduced concentration and digestibility of amino acids in heat-damaged SBM or DDGS is taken into account in diet formulation. Further research is needed to improve the prediction of the ileal digestibility of amino acids in heat-processed ingredients used in practical diet formulations.     

Use of alternative protein sources for fishmeal replacement in the diet of largemouth bass (Micropterus salmoides). Part I: effects of poultry by-product meal and soybean meal on growth,feed utilization,and health

Five isonitrogenous and isocaloric diets [containing 54, 30, 15, 10, and 5% fishmeal crude-protein (CP), dry matter (DM) basis] were prepared by replacing fishmeal with poultry by-product meal plus soybean meal to feed juvenile largemouth bass (LMB, with an initial mean body weight of 4.9 g) for 8 weeks. All diets contained 54% CP and 13% lipids. There were four tanks of fish per treatment group (15 fish/tank). The fish were fed twice daily with the same feed intake (g/fish) in all the dietary groups. Results indicated that the inclusion of 15% fishmeal protein in the diet is sufficient for LMB growth. However, some of the fish that were fed diets containing ≤ 15% fishmeal CP had black skin syndrome (characterized by skin darkening and retinal degeneration, as well as intestinal and liver atrophies and structural abnormalities). The concentrations of taurine, methionine, threonine and histidine in serum were reduced (P < 0.05) in fish fed the diets containing 5, 10 and 15% fishmeal CP, compared with the 30 and 54% fishmeal CP diets. Interestingly, the concentrations of tyrosine and tryptophan in serum were higher in fish fed diets with ≤ 15% fishmeal CP than those in the 54% fishmeal CP group. These results indicated that 15% fishmeal CP in the diet containing poultry by-product meal and soybean meal was sufficient for the maximum growth and feed efficiency in LMB but inadequate for their intestinal, skin, eye, and liver health. A reduction in dietary methionine and taurine content and the possible presence of antinutritional factors in the fishmeal replacements diets containing high inclusion levels of soybean meal may contribute to black skin syndrome in LMB. We recommend that the diets of juvenile LMB contain 30% fishmeal CP (DM basis).

     

Influence of incrementally substituting dietary soya bean meal for rapeseed meal on nutrient digestibility, nitrogen excretion, growth performance and ammonia emissions from growing-finishing pigs

A completely randomised design experiment was performed to examine the effects of replacing different levels of soya bean meal (SBM) with rapeseed meal (RSM) on the growth performance, carcass characteristics, apparent nutrient digestibility, nitrogen (N) balance and manure ammonia emissions of growing-finishing pigs. Pigs (n = 336; mean live weight 42.1 kg) were assigned to one of four dietary treatments containing per kg diet: 210 g SBM; 140 g SBM and 70 g RSM; 70 g SBM and 140 g RSM; and 210 g RSM. All diets were formulated on an ileal digestible amino acid, net energy and available phosphorus basis. There was no significant treatment effect on average daily gain, feed intake, feed conversion ratio and carcass characteristics. There was a linear decrease in gross energy digestibility (p < 0.01) as RSM increased at the expense of SBM in the diet. There was a linear decrease in urinary N excretion (p < 0.01), N digestibility (p < 0.05), total N excretion (p < 0.05) and N retention (p < 0.05) with increasing levels of RSM. There was no effect of dietary treatment on manure ammonia emissions. The results of this study indicate that RSM can be used as a direct replacement for SBM with no associated depression in performance, when formulated on an ileal digestible amino acid and net energy basis. Consumption of diets containing incremental levels of RSM linearly decreased urinary N and total N excretion, reflecting the associated decrease in crude protein concentrations.     

Growth performance, digestibility and faecal coliform bacteria in weaned piglets fed a cereal-based diet including either chicory (Cichorium intybus L) or ribwort (Plantago lanceolata L) forage

Twenty-five weaned 35-day-old piglets were used in a 35-day growth experiment to evaluate the effect of inclusion of chicory and ribwort forage in a cereal-based diet on growth performance, feed intake, digestibility and shedding of faecal coliform bacteria. A total of seven experimental diets were formulated, a cereal-based basal diet (B), and six diets with inclusion of 40, 80 and 160 g/kg chicory (C40, C80 and C160) or ribwort (R40, R80 and R160). Piglets had ad libitum access to feed and water throughout the experiment. Three and five weeks post-weaning faeces samples for determination of digestibility were collected once a day for five subsequent days. Additional faeces samples for determination of coliform counts were collected at days 1, 16 and 35 post-weaning. Piglets fed diet R160 had the lowest average daily feed intake (DFI) and daily weight gain (DWG), and differed (P < 0.05) from piglets fed diets B, R40 and R80. There were no differences in DFI and DWG between the chicory diets and diet B. Inclusion of chicory or ribwort had a minor negative impact on the coefficient of total tract apparent digestibility (CTTAD) of dry matter, organic matter and crude protein, whereas inclusion of both chicory and ribwort resulted in higher CTTAD of non-starch polysaccharides and neutral detergent fibre (NDF). The CTTAD of arabinose were higher for diets C160 and R160 than for diet B (P < 0.05), and the CTTAD of uronic acid was higher for diets C40, C80, C160, R80 and R160 than for diet B (P < 0.05). Age affected the CTTAD for all parameters (P < 0.05) except for NDF, with higher values at 5 than at 3 weeks post-weaning. The coliform counts decreased with increasing age (P < 0.05), but was not affected by treatment. The results indicate that inclusion of up to 160 g/kg of chicory do not negatively affect performance, whereas high inclusion of ribwort have a negative impact on feed consumption and consequently on growth rate. Both herbs have a higher digestibility of fibre compared to cereal fibre. Chicory and ribwort are both promising as feedstuffs to weaned piglets, but the low palatability of ribwort limits the inclusion level.     

Genetic Analysis of Brown Adipose Tissue, Obesity and Growth in Mice

The hypothesis developed from single-gene mutant obese rodents that brown adipose tissue (BAT), through its thermogenic ability, is an important factor in the development of obesity, was tested in a randombred population of mice in which degree of adiposity is polygenically determined. Additive direct genetic parameters for measures of body size, lean, fatness and BAT at 6 wk of age were estimated under control and high-fat postweaning dietary regimens. Heritabilities were generally similar for the two diets. However, the lipid-free dry (LFD) component of BAT had a heritability estimate of 0.70 ± 0.26 on the control diet, but only 0.09 ± 0.20 on the high-fat diet. For all traits, genotype by diet interactions indicated that additive direct genetic rankings were not significantly different for the two diets. Based on estimates of genetic parameters in the control diet, selection for 6-wk body weight or 3- to 6-wk gain is expected to increase body size and adiposity. Selection for BAT weight is predicted to result in large, lean individuals. However, selection for the LFD content of BAT, generally believed to be a better indicator of thermogenic ability, is predicted to increase fatness as well as body size. Selection for LFD as a proportion of 6-wk body weight reduced the expected correlated response in fatness. It was concluded that BAT does not play a major role in determining the correlated response in obesity that is often found in populations selected for large body size.     

Growth performance and gut function of piglets weaned at four weeks of age and fed protease-treated soya-bean meal

Two experiments were carried out to investigate the effects of the protease-treatment of soya-bean meal (SBM) on its composition and nutritive value when fed to piglets weaned at 4 weeks of age in cereal-based diets. In experiment 1, two proteases, active at either alkaline (protease P1) or acid pH (protease P2), were compared with alkali or acid treatment alone. In experiment 2, treatment with protease P2 at acid pH was compared with untreated-SBM, acid-treated SBM, a soya protein concentrate or skim milk powder+fishmeal. Protease treatment increased SBM alpha amino nitrogen concentrations and reduced in vitro SBM antigenicity. Protease P1 reduced in vitro antigenicity to a greater extent than protease P2. However, protease P1 hydrolysed SBM polypeptides non-specifically whereas protease P2 preferentially hydrolysed a high molecular weight polypeptide. In experiment 1, piglets (12 diet⁻¹) fed alkali-treated SBM gained more weight than piglets fed acid-treated SBM in the first 7 days after weaning. Protease P1 did not improve live-weight gain compared with alkali-treatment whereas protease P2 did improve live-weight gain compared with acid treatment. In experiment 2, piglets (24 diet⁻¹) fed protease P2-treated SBM or skim milk powder+fishmeal gained significantly more weight over the first 7 days post-weaning than piglets fed untreated SBM. In neither experiment were there significant differences between diets in piglet serum anti-SBM specific antibodies. There were no consistent changes in small intestine enzyme specific activities in response to the diets fed. Histopathological examination of the small intestine of piglets in experiment 2 revealed no evidence of enteric disease. Neither were there any differences between diets in villus height or crypt depth.     

Effects of diets differing in protein source and technical treatment on digestibility,performance and visceral and biochemical parameters of fattening pigs

The aim of the experiment on 100 cross-bred barrows was to compare commercial diets for fattening pigs based on either soya bean meal (SBM) imported from non-European countries with diets based on a mixture of locally produced rape seed meal, distillers’ dried grains with solubles and soya beans as main protein sources. In addition, these both types of diets were processed by two different technical feed treatments, i.e. coarse grinding without hydrothermal treatment or fine grinding and pelleting. With only few exceptions, nutrients of the diet without SBM were more digestible (p < 0.05) resulting in a higher metabolisable energy (ME) content. Fine grinding and pelleting increased also the ME content and the nutrient digestibility with the exception of crude fibre. Higher feed intake of animals that fed diets without SBM (p < 0.01) resulted in higher average daily gain (p < 0.01). However feeding this diet, the higher digestibility was not reflected in a decreased feed-to-gain ratio (FGR), but fine grinding and pelleting reduced FGR (p < 0.001). A higher pH value and a lower DM content of caecal chymus were detected in animals that received coarsely ground feed (p < 0.05). Animals that fed finely ground and pelleted feed had higher slaughter and relative liver weights and higher blood cholesterol concentrations (p = 0.040). The urea concentrations of blood were lower (p = 0.019) after feeding diets without SBM. In conclusion, SBM imported from non-European countries can be replaced by alternative local protein sources without compromising digestibility or performances of animals. Although fine grinding and thermal treatment particularly seemed to be advantageous for digestibility and performance, the possible risk of development of stomach lesions should be considered.     

Quantifying the genetic parameters of feed efficiency in juvenile Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

Background

Improving feed efficiency in fish is crucial at the economic, social and environmental levels with respect to developing a more sustainable aquaculture. The important contribution of genetic improvement to achieve this goal has been hampered by the lack of accurate basic information on the genetic parameters of feed efficiency in fish. We used video assessment of feed intake on individual fish reared in groups to estimate the genetic parameters of six growth traits, feed intake, feed conversion ratio (FCR) and residual feed intake in 40 pedigreed families of the GIFT strain of Nile tilapia, Oreochromis niloticus. Feed intake and growth were measured on juvenile fish (22.4 g mean body weight) during 13 consecutive meals, representing 7 days of measurements. We used these data to estimate the FCR response to different selection criteria to assess the potential of genetics as a means of increasing FCR in tilapia.

Results

Our results demonstrate genetic control for FCR in tilapia, with a heritability estimate of 0.32?±?0.11. Response to selection estimates showed FCR could be efficiently improved by selective breeding. Due to low genetic correlations, selection for growth traits would not improve FCR. However, weight loss at fasting has a high genetic correlation with FCR (0.80?±?0.25) and a moderate heritability (0.23), and could be an easy to measure and efficient criterion to improve FCR by selective breeding in tilapia.

Conclusion

At this age, FCR is genetically determined in Nile tilapia. A selective breeding program could be possible and could help enabling the development of a more sustainable aquaculture production.

     

Efficacy of virginiamycin and a commercially-available lactobacillus probiotic in swine diets

Eight feeding trials using 708 cross-bred pigs were conducted to evaluate the addition of virginiamycin and a commercially-available lactobacillus fermention product (probiotic) to starter, grower and finisher diets based on maize and soya bean meal. Virginiamycin was added at a level of 11 mg/kg of diet, and lactobacillus probiotic at 1 g/kg in starter diets and 500 mg/kg in grower and finisher diets. In the combined analysis of four starter trials, pigs fed on diets containing virginiamycin tended to eat more and grow faster than pigs fed on the control diet, but feed efficiency was not different. Furthermore, daily gain, daily feed intake and feed efficiency were not improved by the addition of lactobacillus probiotic to starter diets. In the combined analysis of a starter—grower—finisher and a grower—finisher trial, virginiamycin supplementation did not alter overall pig performance compared with control. Pigs fed on a positive control diet containing chlortetracycline, penicillin and sulfamethazine had a nonsignificantly greater daily gain and feed intake.Daily gain for the lactobacillus probiotic-fed pigs was lower (P < 0.05) than that of the negative controls, but daily feed intake and feed efficiency were not significantly different. In three growing—finishing trials in which virginiamycin and lactobacillus probiotic were compared in a 2 × 2 factorial arrangement of treatments, daily gain and feed intakes were greater (P < 0.01) for pigs given virginiamycin. The lactobacillus probiotic did not improve daily gain, feed intake or feed efficiency. Overall, no interaction between virginiamycin and lactobacillus probiotic occurred.     

Fine grinding or expanding of feed as pre-treatment for pelleting in dependence on dietary rapeseed expeller proportion: Nutritional consequences for broilers

Although commercial broiler feed is usually differently conditioned before pelleting, the nutritional consequences of fine grinding or expanding as pre-pelleting treatments are poorly defined so far. Therefore, the effects of these two pre-treatments on nutrient digestibility, broiler performance and digestive tract of broilers were tested. In order to investigate possible interactions between pre-treatments and diet composition two diets differing in rapeseed expeller proportion were tested in a two by two factorial design. Thus, four diets were designed including two diets containing 6% rapeseed expeller (RSE) which were pre-treated by fine grinding (6%FgP) or expanding (6%ExP), and two corresponding diets containing 12% RSE (12%FgP and 12%ExP). For the experiments, 864 male broilers were used. There was a significant diet-by-technical feed treatment (TFT) interaction in case of the digestibility of all considered crude nutrients (p < 0.05). Diet 6%ExP showed higher crude protein digestibility compared to other feeds (p < 0.001). The highest digestibility of organic matter, ether extract, crude fibre and N-free extractives achieved diet 12%FgP. Diets 6%ExP and 12%FgP showed higher N-corrected metabolisable energy content (p < 0.001). TFT affected daily feed intake (DFI) and body weight (BW) gain in a diet-dependent manner (p < 0.001). Feeding of 6%FgP enhanced DFI and BW gain compared to other feeds but 6%ExP reduced both parameters (p < 0.001). Weights of proventriculi and gizzards of animals fed 6%ExP were increased compared with 6%FgP (p < 0.01). In contrast, proventricular length in animals fed 6%FgP was increased compared with diet 6%ExP (p = 0.042). Moreover, animals fed 6%FgP had wider proventriculi than animals fed 12%FgP (p = 0.023). Feed 6%ExP increased proventricular weight compared to 12%ExP (p = 0.001). With regard to the strong relationships between diet and TFT no specific processing method can be recommended according to considered nutritional aspects. A marked prevention of proventricular dilatation due to pellet feeding could not be realised by various used TFT or feed formulations. Used amounts of RSE had no obvious adverse effects on considered nutritional aspects.     

Genetic parameters for performance,feed efficiency,and carcass traits in Senepol heifers

Improving feed efficiency is a key breeding goal in the beef cattle industry. In this study, we estimated the genetic parameters for feed efficiency and carcass traits in Senepol cattle raised in tropical regions. Various indicators of feed efficiency [gain to feed ratio (G:F), feed conversion ratio (FCR), residual weight gain (RG), residual intake and body weight gain (RIG), and residual feed intake (RFI)] as well as growth [final BW, average daily gain (ADG), and DM intake (DMI)], and carcass [rib-eye area (REA), backfat thickness (BF), intramuscular fat score, and carcass conformation score] traits were included in the study. After data editing, records from 1 393 heifers obtained between 2009 and 2018 were used for the analyses. We fitted an animal model that included contemporary group (animals from the same farm that were evaluated in the same test season) as the fixed effect, and a linear effect of animal age at the beginning of the test as a covariate; in addition to random direct additive genetic and residual effects. The (co)variance components were estimated by Bayesian inference in uni- and bivariate analyses. Our results showed that feed efficiency indicators derived from residual variables such as RG, RIG, and RFI can be improved through genetic selection (h² = 0.14 ± 0.06, 0.13 ± 0.06, and 0.20 ± 0.08, respectively). Variables calculated as ratios such as G:F and FCR were more influenced by environmental factors (h² = 0.08 ± 0.05 and 0.09 ± 0.05), and were, therefore, less suitable for use in breeding programs. The traits with the greatest and impact on genetic progress in feed efficiency were ADG, REA, and BF. The traits with the greatest and least impact on growth and carcass traits were RG and RFI, respectively. Selection for feed efficiency will result in distinct overall effects on the growth and carcass traits of Senepol heifers. Direct selection for lower RFI may reduce DMI and increase carcass fatness at the finishing stage, but it might also result in reduced growth and muscle deposition. Residual BW gain is associated with the highest weight gain and zero impact on REA and BF, however, it is linked to higher feed consumption. Thus, the most suitable feed efficiency indicator was RIG, as it promoted the greatest decrease in feed intake concomitant with faster growth, with a similar impact on carcass traits when compared to the other feed efficiency indicators.     

Plant products affect growth and digestive efficiency of cultured Florida pompano (Trachinotus carolinus) fed compounded diets

Costs of compounded diets containing fish meal as a primary protein source can be expected to rise as fish meal prices increase in response to static supply and growing demand. Alternatives to fish meal are needed to reduce production costs in many aquaculture enterprises. Some plant proteins are potential replacements for fish meal because of their amino acid composition, lower cost and wide availability. In this study, we measured utilization of soybean meal (SBM) and soy protein concentrate (SPC) by Florida pompano fed compounded diets, to determine the efficacy of these products as fish meal replacements. We also calculated apparent digestibility coefficients (ADCs) for canola meal (CM), corn gluten meal (CGM), and distillers dried grains with solubles (DDGS), following typical methods for digestibility trials. Juvenile Florida pompano were fed fish-meal-free diets containing graded levels of SBM and SPC, and weight gain was compared to a control diet that contained SBM, SPC, and fish meal. Fish fed diets that contained 25-30 percent SBM in combination with 43-39 percent SPC had weight gain equivalent to fish fed the control diet with fish meal, while weight gain of fish fed other soy combinations was significantly less than that of the control group. Apparent crude protein digestibility of CGM was significantly higher than that of DDGS but not significantly different from CM. Apparent energy digestibility of DDGS was significantly lower than CGM but significantly higher than CM. Findings suggested that composition of the reference diet used in a digestibility trial affects the values of calculated ADCs, in addition to the chemical and physical attributes of the test ingredient.     

Mendelian sampling terms as a selective advantage in optimum breeding schemes with restrictions on the rate of inbreeding

Quadratic indices are a general approach for the joint management of genetic gain and inbreeding in artificial selection programmes. They provide the optimal contributions that selection candidates should have to obtain the maximum gain when the rate of inbreeding is constrained to a predefined value. This study shows that, when using quadratic indices, the selective advantage is a function of the Mendelian sampling terms. That is, at all times, contributions of selected candidates are allocated according to the best available information about their Mendelian sampling terms (i.e. about their superiority over their parental average) and not on their breeding values. By contrast, under standard truncation selection, both estimated breeding values and Mendelian sampling terms play a major role in determining contributions. A measure of the effectiveness of using genetic variation to achieve genetic gain is presented and benchmark values of 0.92 for quadratic optimisation and 0.5 for truncation selection are found for a rate of inbreeding of 0.01 and a heritability of 0.25.