Effects of different rearing systems on muscle and meat quality traits of slow- and medium-growing male chickens

1. This experiment was conducted to evaluate the effect of production system on the meat quality of slow- and medium-growing chickens. A total of 1075 1-d-old male chicks were equally divided into 6 experimental groups, represented by three strains (SG: TETRA-H, MG1: TETRA HB Color, MG2: Shaver Farm) and were reared in a poultry house in floor pens (12 males/m²).

2. On d 49, 150 healthy birds (50/genotype) were placed in a free-range family farm while the rest of the birds remained indoors. All birds were fed ad libitum and consumed the same diet. On d 70, 20 birds of each experimental group were slaughtered and muscle samples were taken from the left breast and thigh muscles.

3. Thigh muscle of SG males kept on free range was darker (L* = 75.12 vs. 78.33) with lower frying loss (45.9% vs. 55.9%) compared with the indoor group. Similar results were obtained from the MG1 group. Free-range MG2 males had lighter thigh meat (L* = 50.7 vs. 57.8) and lower frying loss compared to the indoor group.

4. In general, the indoor treatment had a lower impact on breast meat than the outdoor system. Regardless of the rearing system, genotypic differences were more pronounced in thigh than in breast muscle.

     

Effect of intermittent feeding,structural components and phytase on performance and behaviour of broiler chickens

1. Two experiments were conducted to study the effect of intermittent feeding on performance and the efficacy of an exogenous phytase, and to assess whether intermittent feeding changed the activity pattern of broiler chickens.

2. Broiler chickens were given, either ad libitum or intermittently, a phosphorus deficient pelleted diet containing either coarsely or finely ground oat hulls and either no enzyme or a phytase added from 10 d of age, in a 2 × 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 1-h feeding bouts/d and one 2-h feeding bout/d from d 14.

3. Performance, characteristics of the anterior digestive tract and phosphorus retention were assessed in experiment 1, while in experiment 2, birds were observed during 4-h periods to quantify different behaviours.

4. Intermittent feeding and phytase improved performance, but intermittent feeding did not improve the efficacy of the enzyme added. Ad libitum fed broiler chickens ate and drank on average twice per hour, and spent close to three-quarters of their time resting. Apart from an increased standing and feed searching activity for intermittently fed birds compared to ad libitum fed birds during the last hour before feed was presented, no differences in activity was detected.

5. It was concluded that broiler chickens quickly adapt to intermittent feeding without reduction in final body weight and with improvements in feed efficiency, but without improving the efficacy of dietary phytase. Only small changes occur in the behaviour of intermittently fed birds compared to ad libitum fed birds.     

The use of conditioned place preference to determine broiler preferences for quantitative or qualitative dietary restriction

1. Calcium propionate (CAP) may improve the welfare of feed restricted broiler breeders by improving their satiety when included within the feed ration. However, the evidence for this is mixed.

2. This study used a closed economy conditioned place preference (CPP) task and aimed to identify whether broilers (as a model for broiler breeders) preferred an environment associated with quantitative food restriction (QFR) or an environment associated with a diet quality-adjusted by the inclusion of CAP. Birds taught to associate different environments with QFR and ad libitum (AL) access to feed were used to validate the methodology.

3. The two treatment groups were (1) QFR/AL (n?=?12) in which birds alternated every 2?d between QFR and ad libitum access to food, and (2) QFR/CAP (n?=?12) in which birds alternated every 2?d between QFR and QFR?+?calcium propionate (increased from 3–9% over the study period). Birds were taught to associate one diet option with vertical stripes and the other with horizontal black and white stripes. Each bird was tested twice for a CPP (once per diet).

4. QFR/AL birds showed a significant preference for the pen associated with ad libitum access to feed, but only when tested hungry (i.e. fed QFR on day of testing). QFR/CAP birds did not show a preference under either hunger state.

5. Reasons for the failure of QFR/CAP birds to show a preference are unclear but could include a lack of preference or failure to learn the task.

6. The existence of state-dependent effects indicates that care is needed in the design of future CPP studies and that the effect of calcium propionate and level of hunger on ability to learn a CPP needs further investigation.     

Early and 24 h post-mortem changes in breast muscle quality traits of two turkey genotypes and their reciprocal crosses raised under semi-confined conditions

1. An experiment was conducted to determine the effect of reciprocal crossing of turkeys on early and 24 h post-mortem changes in quality traits of their breast muscles.

2. The turkeys of slow-growing (SG) and fast-growing (FG) lines as well as SF (SG × FG) and FS crosses (FG × SG) were reared with access to free range.

3. After slaughter turkey breast muscles were examined in the following terms: 5 min, 45 min, 2 h and 24 h post-mortem, for: temperature, pH, glycogen content (G), lactate content (L) and electrical conductivity (EC). Quality attributes of the breast meat were evaluated based on chemical composition, water holding capacity (WHC), cooking loss (%), shear force (N) and colour (L*, a*, b*).

4. Despite differences in the rate of post-mortem changes, the genotype of turkeys had no significant effect upon many quality traits assessed 24 h post-mortem. Meat of lighter birds (SG and SF) was characterised by a lower fat content but a similar protein content compared to meat of FS and FG turkeys. In addition, meat of males from these groups was darker. Meat from the breast muscles of heavier birds (FS and FG) was harder.

5. Significant negative maternal effects were determined for temperature of meat of both male and female turkeys, for pH₂ and EC₂₄ of males as well as for L₂, L₂₄ and cooking loss of female meat. Positive heterosis was confirmed only for pH₂ of female meat and for G₂ of male meat.

6. In summary, the direction of fast- and slow-growing turkey crossing may affect the quality of their meat. However, meat of both types of hybrids reared under semi-confined conditions (with the possibility of using free range) was characterised by appropriate quality parameters.

     

Performance,carcass and technological meat quality of pigs in indoor and outdoor production systems

Abstract

This study aimed to compare different production systems, i.e., the combined effect of outdoor and indoor rearing of pigs and organic diets fed ad libitum or restrictively. Furthermore, the suitability of two breed crosses for outdoor rearing was studied. The effects on performance, carcass and technological quality traits were investigated. During two years, 240 pigs of Duroc x Large White (D*LW) and Swedish Landrace x Large White (L*LW) were allocated to three production systems: 1) Pigs kept outdoors, fed an organic diluted diet (20% alfalfa roughage) ad libitum; 2) Pigs kept outdoors, strategically fed a diluted organic diet up to a live weight of approximately 80 kg and thereafter an undiluted organic diet ad libitum; 3) Pigs kept indoors, fed an undiluted organic diet restrictively. For outdoor pigs, strategic feeding increased daily weight gain and backfat thickness, compared with feeding a diluted diet throughout (p≤0.01). L*LW pigs in both outdoor systems grew slower than in the indoor system (p≤0.001), whereas for D*LW pigs only outdoor pigs fed the diluted diet had a slower growth rate. Outdoor pigs had lower dressing percentage than indoor pigs. Glycogen content and L* values in M. longissimus dorsi were higher, whereas b* values were lower in meat from pigs in the indoor system. D*LW pigs had higher water-holding capacity (lower drip, thawing and cooking losses), lower shear force and higher intramuscular fat content compared with L*LW pigs.     

Sensorial quality and bone strength of female and male broiler chickens are influenced by weight and growth rate

1. An experiment was conducted with 98 male and 98 female broiler chickens (Ross 308) to study the effect of growth rate, induced by different dietary means, sex and live weight (1500?g and 2000?g) at slaughter on production parameters, bone strength and sensorial characteristics of the breast meat.

2. The birds were divided into four groups and individually fed a standard commercial diet, a high energy diet or low energy diet from d?11 to slaughter at between d 28 and 39. Three groups were fed ad libitum and a further group was fed a restricted amount of the high energy feed. Half of the birds in each group were slaughtered at approximately 1500?g and the other half at 2000?g live weight.

3. The diets resulted in different growth rates. The chickens fed the high energy and the commercial diet had the highest growth rate at both live weights at slaughter. The restricted fed chickens had lower bone strength than the chickens fed the low energy diet.

4. Breast meat from male broilers was juicer, more tender and less hard than breast meat from females. Chickens slaughtered at 2000?g live weight were juicer than those slaughtered at 1500?g. Chickens given the high energy feed ad libitum and restricted had different growth rates, but the sensory parameter related to texture showed no difference.

5. It was concluded that an increased slaughter weight might improve meat quality due to improved juiciness.     

Early and 24 h post-mortem thigh (ilio tibialis) muscle metabolism and meat quality in two genetic types of turkeys and their reciprocal crosses,raised under semi-confined conditions

1. The experiment was conducted in order to determine the effect of the direction of turkey crossing on quality traits of their thigh muscle.

2. In total, 1358 turkeys of slow- (SG) and fast-growing (FG) lines as well as SF crosses (SG × FG) and FS crosses (FG × SG) were reared with access to free range to 21 weeks of age in the case of males and 15 weeks of age in the case of hens.

3. After slaughter of 15 males and 15 hens from each genetic line, their thigh muscles were examined and the following traits were measured after 5-min, 45-min, 2-h and 24-h post-mortem: temperature, pH, glycogen content (G), lactate content (L) and electrical conductivity (EC). Quality attributes were evaluated based on chemical composition, water holding capacity, cooking loss (%) and colour.

4. The rate of post-mortem changes in temperature, G, L and pH in muscles differed among the 4 lines of turkeys, with the highest metabolic rate determined for muscles of SG turkeys, followed by muscles of SF, FS and FG birds. A more beneficial muscle water holding capacity of both sexes of turkeys and better results of cooking loss in male muscles were found in SG and SF turkeys. The thigh muscles of the crosses were characterised by a higher content of protein and a lower content of fat compared to the muscles of FG turkeys, and in the case of the males also by a higher protein content compared to the muscles of SG birds.

5. Owing to the faster post-mortem metabolism, better water holding capacity, lower cooking loss and fat content at a similar content of protein, the thigh muscles of SF crosses raised in the free range system represent a better quality of meat for consumers compared to the thigh muscles of FS turkeys.     

The effect of dietary energy concentrations on production variables of ostrich chicks (Struthio camelus var. domesticus)

1. The effects of different dietary energy concentrations on ostrich production variables were examined in two separate trials. The first trial tracked changes in production variables from the pre-starter phase through the starter phase and grower phase. The second trial was based on the finisher phase per se. In both trials, the influence of dietary energy on feed intake, feed conversion ratio (FCR) and growth variables was investigated. Additionally, basic abattoir weights were recorded, and measurements of the feathers and skin were performed.

2. In both trials, three diets with different concentrations of dietary energy were given during each phase where the low-, medium- and high-energy concentrations for each phase were as follows: 13.5, 14.5 and 15.5 MJ ME/kg feed pre-starter; 12.5, 13.5 and 14.5 MJ ME/kg feed starter; 10.5, 11.5 and 12.5 MJ ME/kg feed grower and 9.5, 10.5 and 11.5 MJ ME/kg feed finisher. Feed and water were available ad libitum in both trials.

3. Overall, it was found that the best performance for growth, FCR, skin size and grade, live weight, carcass weight and thigh weight were obtained on the medium-energy diet during the pre-starter, starter and grower phases.

4. During the finisher phase, improved growth rate and tanned skin size was found in birds given the diet with the highest energy concentration (11.5 MJ ME/kg feed). Carcass weight, growth rate and certain feather variables were also significantly influenced by gender.

     

Physicochemical properties of breast meat from water-stressed naked-neck and Ovambo chickens

1. Differences in growth performance, physicochemical properties and fatty acid composition of breast muscle from water-stressed 16-week-old naked-neck (NNK) and Ovambo (OVB) chickens were investigated.

2. OVB chickens had superior (P < 0.05) slaughter weights at 16 weeks of age, average daily gain (ADG) and average daily water intake (ADWI) than NNK chickens. Body weights of birds at 16 weeks of age, ADG, average daily feed intake (ADFI), ADWI and water to feed ratio (WFR) declined progressively with increasing severity of water restriction while the opposite was observed for feed conversion ratio (FCR) values. NNK chickens had better FCR at the 40% of ad libitum water intake than OVB chickens.

3. Meat from NNK chickens had higher redness (a*) values at the 40% of ad libitum water intake but lower lightness (L*) and yellowness (b*) values at 70% of ad libitum and ad libitum water intakes compared with OVB chickens.

4. There was no interaction between strain and water intake on most fatty acids, except for the proportion of elaidic acid (C18:1t9) higher in meat from NNK compared with OVB chickens given water at 40% of ad libitum. Water restriction to 40% of ad libitum water intake had a positive influence on the proportions of linoleic acid (C18:2n-6), arachidonic acid (C20:4n-6), adrenic acid (C22:4n-6), docosahexaenoic acid (C22:6n-3), total polyunsaturated fatty acid (PUFA), total omega-3 PUFA and total omega-6 PUFA proportions, but resulted in lower proportions of total monounsaturated fatty acids (MUFAs) compared with 70% of ad libitum and ad libitum water intakes.

5. It was concluded that cooking loss, meat redness values, omega-3 and omega-6 PUFA proportions and n-6/n-3 ratio of NNK chickens improved with increasing severity of water restriction compared with OVB chickens.     

Role of body weight and food intake after photostimulation on ovarian function at first egg in broiler breeder females

1. The role of body weight during rearing and food allocation after photostimulation on ovarian function in broiler breeder females was examined in two experiments. In experiment 1 birds were fed ad libitum, or to grow to 0.7 or 0.4 of ad libitum‐fed body weight at 20 weeks of age. After photostimulation at 16, 19 and 22 weeks respectively they were fed ad libitum, 145 g/d or 115 g/d in a factorial design. The ovary of each bird was examined after it had laid an egg. In experiment 2, restricted birds (0.4 of ad libitum‐fed body weight) were fed 125 g/d after laying an egg or ad libitum and a third group were given 125 g/d for 3 to 4 weeks and then fed ad libitum. The ovaries of these birds were examined 6 to 7 weeks after their first egg.

2. Food restriction after photostimulation had little effect on ovarian function in birds fed ad libitum during rearing. These birds had 2 to 3 hierarchies of yellow follicles of similar size. Restricted birds fed ad libitum after photostimulation had a large increase in the numbers of yellow follicles (1.7 to 2.0 hierarchies) compared with birds fed 145 g/d or 115 g/d which had 1.2 to 1.6 hierarchies of yellow follicles.

3. Age at first egg was largely a function of rearing treatment but feeding 115 g/d to the 0.4 treatment birds delayed the onset of lay compared with the other treatments.

4. Ad libitum feeding in restricted birds after the onset of lay resulted in a similar increase in the number of yellow follicles as the response to ad libitum feeding after photostimulation.

5. The prevalence of birds with atretic follicles was relatively high in birds fed ad libitum during rearing and in restricted birds fed ad libitum after photostimulation.

6. Yolk weight increased with age at photostimulation and food restriction decreased yolk weight by about 1 g compared with ad libitum feeding after photostimulation.     

Effect of synbiotic supplementation and dietary fat sources on broiler performance,serum lipids,muscle fatty acid profile and meat quality

1. A 42-d trial was conducted to investigate the effect of adding a synbiotic supplement to diets containing two different types of fat on performance, blood lipids and fatty acid (FA) composition and oxidative stability of breast and thigh meat in broilers.

2. A total of 800 one-d-old male broiler chickens were randomly assigned into 1 of 8 treatments with 4 replicates of 25 birds per treatment. The experiment consisted of a 4 × 2 factorial arrangement of treatments including 4 concentrations of synbiotic (0, 0.5, 1 or 1.5 g/kg diet) and 2 types of fat [sunflower oil (SO) or canola oil (CO)] at an inclusion rate of 50 g/kg diet.

3. Dietary fat type did not affect body weight gain (BWG) or feed conversion ratio (FCR) during the overall experimental period (0–42 d). However, fat type modified serum lipid profile and FA composition and 2-thiobarbituric acid-reactive substances (TBARS) content in breast and thigh meat.

4. The addition of synbiotic to the diet linearly improved overall BWG and FCR and also decreased serum cholesterol and low-density lipoprotein cholesterol concentrations. The TBARS value in thigh meat after 30 d of storage at 4°C was linearly decreased as the synbiotic inclusion concentrations in the diets increased. Dietary synbiotic also decreased the proportion of monounsaturated fatty acids and increased n-6 polyunsaturated fatty acid (PUFA) concentration in thigh meat, whereas the FA profile of breast meat was not affected by synbiotic supplementation. Moreover, the PUFA/SFA ratio in the breast meat was linearly increased when synbiotic was included in the CO-containing diets.

5. In conclusion, the addition of synbiotic to broiler diets had a positive effect on growth performance, blood lipid profile and meat quality. The results also support the use of synbiotic to increase the capacity of canola oil for enhancing PUFA/SFA ratio of breast meat in broilers.

     

Adaptation of light‐bodied chicks to meal feeding: Gastrointestinal tract and pancreatic enzymes

1. Two‐week old male chicks of a light‐bodied strain were either fed ad libitum or given one (1M) or two (2M) 2‐h meals per day. A fourth group was pair‐fed (P1M) the amount of food which had been consumed by the 1M group on the preceding day.

2. Compared with ad libitum‐fed counterparts, a marked increase in the relative weight of the storage organs (crop and gizzard) was observed in the meal‐fed birds. The relative weight of the intestine was not affected by meal feeding but the ileal wall became thinner.

3. After food deprivation for 14 or 22 h, respectively, for the ad libitum and the meal‐fed chicks, the weights of contents in the gastrointestinal tract (GIT) segments did not differ between treatments except for those of the gizzard and caecum. Food restoration resulted in an increase in the contents of the GIT of meal‐fed chicks. The increments in the crop and gizzard contents were related to the severity of food restriction. The contents of the intestinal segments were quite similar in all treatments.

4. The activities of the digestive enzymes in the pancreas, expressed as units/g pancreas or units/kg body weight, were not significantly affected by feeding regime. In the small intestine of the meal‐fed birds, marked increases in specific (units/g content) and relative (units/kg body weight) activities were observed of amylase and chymo‐trypsin when compared with their ad libitum‐fed counterparts. The effect of meal feeding on trypsin activities was less pronounced.     

Raised environmental temperature and food rationing as means of restricting growth of the replacement pullet

1. Four rearing temperature regimes (15, 20, 25, 30 °C) and three feeding schedules (ad libitum, restricting to the ad libitum intake of the 12th week and feeding 70% of this rate) were carried out with layer replacement pullets to 170 d of age. From this age, during lay, birds were kept at either 21 °C or on a 24‐h cycle of 21 for 18 h and 28 °C for the 6 h before lights out. Both a white and a brown egg‐laying strain were used.

2. Body weight at 169 d of age varied from, on average, 1409 g (15 °C, ad libitum) to 943 g (30 °C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 °C.

3. Rearing at 30 °C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing.

4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21–28 °C cycle, however, appeared small.     

Liver colourations as well as performance and digestive tract characteristics of broilers may change as influenced by stage and schedule of feed restriction

To investigate the changes in characteristics (CIE L*, a* and b*) of liver colour as well as growth, carcass and digestive tract of broilers as influenced by stage and schedule of feed restriction, 400 two‐week‐old broilers (Ross 308) were randomly assigned to 20 floor pens. Four replicate pens of 20 equally mixed sex birds per pen were randomly allotted each of the five treatments. Birds in control were fed ad libitum. Birds in QFRM and QFRL were restricted 75% of ad libitum intake (quantitative feed restriction, QFR) for 10 days. Birds in FTRM and FTRL were fed ad libitum for 7 days per a period of 10 days with third, fifth and seventh days of feed withdrawal (feeding time restriction, FTR). The restrictions in the QFRM and FTRM started on day 14 (at middle age, M) while the restrictions in the QFRL and FTRL started on day 31 (at late age, L). The restricted broilers consumed less feed than the full‐fed birds (p < 0.05). The QFRM and FTRM birds consumed less feed than QFRL and FTRL birds (p < 0.05). The body weight gain decreased by the QFRL and FTRL, the feed efficiency increased by the QFRM and FTRM compared to other treatments (p < 0.05). The QFRL and FTRL increased a* and b* values of liver and the relative weights of gut and liver, and the FTRL increased the L* value of liver compared to other treatments (p < 0.05). The QFRL and FTRL decreased the relative weight of abdominal fat compared to the control (p < 0.05). In conclusion, (i) the restricted feeding at middle stage improved feed efficiency; (ii) the restricted feeding at later stage decreased growth rate and abdominal fat; and (iii) limited‐time feeding during later period caused a measurable variation in the liver colour.     

Influence of dietary amino acid level on performance,carcass quality and health of organic pigs reared indoors and outdoors

Abstract

The influence of dietary amino acids on performance and carcass quality was studied in 192 organic indoor and outdoor pigs given diets with different amino acid levels (recommended amino acid level, 7% and 14% lower) ad libitum in a two-phase feeding system. During phase 2, daily consumption of lysine, methionine+cystine and threonine was higher for outdoor than indoor pigs independent of amino acid level (p=0.002, 0.004 and 0.006, respectively). The outdoor pigs grew faster during phase 2 than the indoor pigs (p=0.001), although feed conversion ratio did not differ (p=0.358). Dressing percentage was higher for outdoor than for indoor pigs (p=0.011) but lean meat content did not differ (p=0.904). The health status of the pigs was evaluated and showed that the incidence of pigs seropositive to erysipelas was higher outdoors. Ascaris suum was present in both production systems, whereas Eimeria sp. only was found among outdoor pigs. The results indicate a discrepancy between pigs housed in different production systems rather than between pigs directed to different dietary amino acid levels. This suggests that growing/finishing pigs fed ad libitum can compensate for dietary amino acid levels lower than the current Swedish recommendations without affecting production results.     

Body weight,meat quality and blood metabolite responses to carbohydrate administration in the drinking water during pre‐slaughter feed withdrawal in broilers

This study was conducted to determine weights of body (BW), carcass (CW), gastrointestinal tract (GTW), meat quality and some blood metabolite responses to corn starch, saccharose or glucose administration in the drinking water during pre‐slaughter feed withdrawal (FW) in broilers. On day 42 of age, 200 broilers (Ross 308) were allocated randomly to five treatments with four replicates. During a 10‐h FW, control broilers (C) were provided with non‐treated water and the standard finisher diet ad libitum, whereas fasted broilers provided with non‐treated (NFW) or treated water, 3 g glucose (G), saccharose (S) or corn starch (CS)/L. Eight birds (four males and four females) per treatment were slaughtered. Birds receiving non‐treated or treated water had lower BW and higher carcass yield than the full‐fed broilers. The full‐fed broilers had higher absolute and relative GTW than the fasted birds. Broilers consumed more readily treated water compared with non‐treated water. While the a* value of breast meat from CS birds was higher than that from NFW, the b* value of that was higher than S and C birds. The c* values of breast meat from S birds were lower compared with that from the CS treatment. The thigh meat from NFW broilers had higher h* value than that from C and G broilers. The thigh meats of C and CS broilers had higher c* value than that of G birds. The full‐fed broilers had higher plasma triglyceride concentration than NFW, S and G birds. The full‐fed broilers had higher plasma uric acid and uric acid nitrogen concentrations than S birds. These results show that carbohydrate administration in the drinking water cannot be a good alternative for the FW period before slaughter due to the fact that the carbohydrates do not reduce BW losses and do not lead to increases in meat quality.     

Effect of sex and feeding system on feed intake, growth, and meat and carcass characteristics of fattening Assaf lambs

The effect of feeding system and sex on intake, growth and carcass and meat characteristics of Assaf fattening lambs was studied. Twenty four weaned Assaf lambs, half males and half females were used. After an adaptation period, lambs were randomly assigned to one of the two feeding systems studied. Control lambs received ad libitum commercial concentrate (70% barley, 22% soybean meal, 4.8% wheat, 0.5% bicarbonate, 2.7% mineral–vitamin premix) and barley straw. Free Choice lambs had ad libitum and separate access to whole barley grain and a protein supplement (73.3% soyabean meal, 16% wheat, 1.7% bicarbonate, 9% mineral–vitamin premix). Lambs were slaughtered at 25 kg LBW. Feed intake was not significantly affected by sex (P > 0.05) but Free Choice lambs showed higher dry mater intake than the Control lambs. Nevertheless, only males from the Free Choice group showed an improvement in feed efficiency rate (P < 0.05) and average daily gain (P < 0.01) relating to the Control lambs. Neither feeding system nor feeding system × sex interaction significantly affected non-carcass weight, fat depots, cold carcass weight, dressing percentage, main proportions of commercial cuts and meat characteristics (P < 0.05). As it was expected, female lambs showed a lower average daily gain and a higher feed conversion efficiency than male lambs (P < 0.001) which was related to a greater fat deposition. Meat characteristics were unaffected by sex, with the exception of longissimus lumborum fat content, which was higher in female lambs.The present results suggest that Free Choice feeding system might be suitable for intensively reared male lambs since improvements in daily weight gain and feed conversion rate were achieved, with no adverse effect on carcass and meat quality. Despite the selected diet of both, males and females, did not differ in the crude protein content, the use of Free Choice feeding system for female lambs did not improve performance compared to the Control group.     

The effects of strain and incremental improvements in feed form on d 28 to 42 male broiler performance

Feeding high-quality pellets to modern commercial broilers may maximize genetic potential; however, this typically requires an increased cost to produce feed. Therefore, it is important to determine if incremental improvements in feed form (FF) can increase performance of modern broiler strains. The current study was conducted to investigate the effects of feeding modest improvements in feed form (50, 60, 70, or 80% intact pellets; IP) to 2 commercial broiler strains (fast-growing or high-yield) on d 28 to 42 growth performance and processing variables. A common diet was manufactured to contain 80% IP, of which a portion was ground to create a total of 4 FF treatments varying in IP to ground pellet ratios: 50:50; 60:40; 70:30; and 80:20. Fast-growing (FG) birds demonstrated improvements in body weight (BW), BW gain (BWG), and feed conversion ratio (FCR) when compared to high-yield (HY) birds. For the main effect of FF, feeding 80 vs. 50% IP reduced d 28 to 42 FCR. Also, feeding birds 80% IP vs. all other FF treatments improved d 28 to 42 BWG and d 42 BW. A Strain × FF interaction established that FG broilers fed 50, 60, and 70% IP diets had higher d 43 total breast yield than HY birds fed the same FF treatments; however, both strains demonstrated similar total breast yield when 80% IP were fed, which suggests that FG broilers are less sensitive and HY broilers are more sensitive to increasing FF. These data suggest a distinct benefit for feeding improved FF from d 28 to 42 to modern broilers.     

Effects of humic substances supplementation provided through drinking water on performance,carcass traits and meat quality of broilers

The present study aimed at evaluating the effects of different doses of humic substances (HS) in waterer pan on broiler performances and meat quality. For the trial, 480 chicks (ROSS 308) were allocated into four groups (HS0, HS150, HS300 and HS450) of 120 equally mixed‐sex birds, each receiving a drinking water supplemented with 0, 150, 300 and 450 ppm of a humic acid (provided by 0.0%, 0.5%, 1.0% and 1.5% of HS, v/v) respectively. At the age of 21 and 42 days, feed consumption and live weight were taken. At the age of 42 days, 16 birds per treatment were slaughtered, dressing percentages, digestive tract traits were evaluated and samples of breast (pectoralis major) and thigh (iliotibialis) meat were taken to evaluate the changes in colour characteristics (CIE L*, a* and b*) and chemical composition. The body weight gain increased by the HS300 in relation to the HS0 and HS450, and decreased by the HS450 in relation to the HS0. The feed consumption of birds in the HS450 and feed efficiency of birds in the HS300 were lower and higher than those in the other treatments respectively. The carcass weight of broilers in the HS150 and HS300 were higher than those of in the HS0 and HS450. The carcass weight decreased by the HS450 in relation to the other treatments. The dressing percentage increased by the HS150 in relation to the HS450. The HS450 resulted in breast and thigh meat colour that were lighter than those found in the HS0 birds. The HS450 increased fat content of thigh meat in relation to the HS0. It was concluded that the humic acid supplementation at 300 ppm and 450 ppm appears to have a measurable impact on live performance improving feed efficiency and lightness of breast and thigh meat colours in broilers respectively.