Changes In Carcass Composition Research Articles

Effect of extended days on feed on carcass gain, efficiency, and quality of individually fed beef steers.

Crossbred steers (n = 114, initial BW = 334kg; SEM = 5kg) were serially harvested to evaluate the change in carcass composition by feeding cattle 21 or 42 d longer than the 2014 industry average subjective measure of finish, 1.27cm of 12th rib fat thickness. Carcass ultrasound measurements were collected on 76 steers at 1, 78, and 134 days on feed (DOF) to project appropriate harvest date. Steers were sorted into three harvest groups, and serially harvested at 142, 163, or 185 DOF, with the first harvest date selected based on an estimated 12th rib fat thickness of 1.27cm via ultrasound measurement. Steers were fed using an individual animal feeding system, to determine individual performance metrics. Steer DMI did not differ (P ≥ 0.31) between harvest groups, while carcass-adjusted ADG and G:F decreased linearly (P ≤ 0.04) as DOF increased. Carcass weight increased linearly (P < 0.01) as DOF increased from 142 to 185 DOF, with steers gaining an additional 36kg of HCW when fed an additional 42 DOF. Carcass LM area quadratically increased (P = 0.04) to 163 DOF and remained constant to 185 DOF. Marbling score was not different (P = 0.14) between harvest groups; however, the opportunity to grade USDA Premium Choice was improved for steers fed to 185 DOF. Calculated YG and 12th rib fat thickness increased linearly (P < 0.01) as DOF increased, with distributions across YG 1 through 5 differing between harvest groups (P < 0.01), and 185-d carcasses having the greatest frequency of YG 4 carcasses. As cattle are fed for additional DOF, live ADG and G:F decline, while HCW and LM area increase.

Changes in Carcass Composition, Meat Quality Traits, and Stress Levels in Culled Sows Exposed to Different On-Farm Rest Periods

The study investigated the effect of on-farm rest period (RP) on carcass composition, meat quality, and stress indicators of culled sows. The study was conducted on 84 Large White × Landrace culled sows, which were divided into seven groups (n = 12) with respect to the duration of the on-farm rest period: no rest period (N-RP) group and 1 to 6 weeks of on-farm rest period (1–6 RP). After completion of the on-farm RP, each group of culled sows was slaughtered and the carcass and meat quality traits were determined. Sows from 6-RP had a significantly higher dressing percentage and backfat thickness and, together with sows from 5-RP, a higher shoulder weight. The highest shoulder percentage was found in the 3-RP and 4-RP groups, while 1-RP had the highest percentage for the belly–rib part. At the same time, RP influenced the final pH values (pH24 SM and pH24 LL) measured in the longissimus thoracis et lumborum (LT) and in the musculus semimembranosus (SM), as well as drip loss, thawing loss, cooking loss, and tenderness. As far as the stress indicators are concerned, statistical differences between groups were only found in the cortisol level, which was lowest in 6-RP. The results show that RP has a positive effect on meat quality traits and carcass composition. In addition, prolonged RP has a positive effect on the levels of stress indicators.

Chromium propionate supplementation alters animal growth performance, carcass characteristics, and skeletal muscle properties in feedlot steers

The objective of this study was to evaluate the effects of increasing concentrations of Cr propionate (CrP) on feedlot performance, blood parameters, carcass characteristics, and skeletal muscle fiber properties in feedlot steers. Crossbred steers (n = 32; 367 ± 2.5 kg; 16 pens; 2 hd/pen) were blocked by body weight (BW), and treatment was randomly assigned to pen: (1) 0 mg added Cr/kg diet dry matter (DM) (control), (2) 0.15 mg added Cr/kg diet DM (CrP; KemTRACE Chromium 0.04%, Kemin Industries, Des Moines, IA), (3) 0.30 mg added Cr/kg diet DM, and (4) 0.45 mg added Cr/kg diet DM. Steers were fed ad libitum, and the treatment was top-dressed at the time of feeding. Body weights, blood samples, and longissimus biopsies were collected before feeding on days 0, 28, 56, 91, 119, and 147. Blood sera were harvested for analysis of glucose, insulin, sera urea nitrogen, and non-esterified fatty acid concentrations. Longissimus biopsies were collected for gene expression, protein expression, and immunohistochemical (IHC) analysis. Pen was the experimental unit for live and carcass data, and steer was the experimental unit with day as a repeated measure for sera and IHC analyses. For the entire duration of the trial, a linear increase in average daily gain (ADG) (P = 0.01) and improvement in G:F was observed (P = 0.01) with no change in DMI (P = 0.11) with increasing CrP. A linear increase in hot carcass weight (HCW) (P ≤ 0.01) with no other changes in carcass composition were noted (P ≥ 0.38) as the level of dietary CrP increased. There was no effect of treatment on any sera parameters measured (P ≥ 0.10). No difference was detected for gene or protein expression of glucose transporter type 4 (GLUT4) due to CrP supplementation (P ≥ 0.10). For skeletal muscle fiber distribution and cross-sectional area, there was no effect of treatment (P ≥ 0.10). Density of total GLUT4 did not change due to CrP (P ≥ 0.10). Internalization of GLUT4 was increased in the 0.30 and 0.45 mg/kg treatments (P < 0.01). For total nuclei density and myonuclei density, there were treatment × day interaction tendencies (P ≤ 0.08). Supplementation of CrP did not alter density of satellite cells (P ≥ 0.10). The number of transporters located in the sarcolemma of skeletal muscle fibers did decrease, implying fewer proteins were needed to transport extracellular glucose into the muscle fiber. Therefore, CrP may augment cellular function and growth via increased efficiency of GLUT4 function. These results indicated CrP increases BW, ADG, and HCW, without changes in circulating sera parameters or total GLUT4 expression.

Changes in carcass composition of Black Slavonian pigs and their crossbreds with Duroc during growth

Present study was carried out on 32 pure Black Slavonian (BS) pigs and 32 crossbreds of Black Slavonian and Duroc (BSxDu); number of barrows and gilts was equal in both groups. Every three months, 4 barrows and 4 gilts from both groups were slaughtered for the analysis of tissue and primal parts development in the series of subsequent dissection trials covering a total fattening period of 12 months. The results showed that crossing the BS pigs with Duroc resulted in significant increase in the development of main tissues and primal parts. Significantly higher live weight, carcass weight and lean meat percentage was reported in BS pigs compared to BSxDu pigs (P<0.001). The exception was lean meat percentage determined at the age of 3 months (P>0.05). BSxDu pigs entered the experiment at significantly higher live weight (P<0.05) than BS pigs; this relationship continued during entire growth period. Muscle and fatty tissues followed the similar patterns of growth. Muscle tissue was produced in higher amounts than fat in case of BS pigs; in BSxDu pigs, fat overgrew muscle at the later stage of fattening. Although BS pigs exhibited lower formation of muscle tissue than BSxDu, their carcasses were significantly leaner.

INFLUÊNCIA DA TEMPERATURA NA PRODUÇÃO E BEM-ESTAR DE SUÍNOS

The response of pigs to thermal stress consists, mainly, of the intensification of heat dissipation by evaporation through the respiratory tract, followed by reduction in food consumption, with a consequent reduction in energy intake, constituting an effort by the animal to reduce heat production metabolic. Many of these physiological and metabolic responses lead to lower growth rates, poor feed utilization efficiency and changes in carcass composition. Pigs are animals with excellent levels of production and reproduction, but one of the challenges of swine farming is mainly related to maximum exploitation of their genetic potential. When confined in intensive systems, the animals are put under adverse conditions, thus, they change their behavior in a general way and mainly in relation to the food intake, which is changed, occurring then fall in their zootechnical indexes, mainly by the changes in the habits feed. Thus, the objective of this work is to present a review on the influence of temperature variation on the production and well-being of pigs, and pointing out the main physiological changes that occur with pigs submitted to these conditions.

Effect of animal age and trimming practices on the physical composition of Bonsmara beef

Increased economic incentive for producing young and leaner carcasses, as well as demand for lean meat from progressively health conscious consumers, are considered drivers for change in carcass composition over time. Furthermore, many retailers trim visible fat from meat to various degrees and consumers increasingly remove visible fat from meat prior to, or after, cooking.The objective of this study was to determine the composition of South African Bonsmara beef from four age groups from different production systems, as well as to extrapolate the effect of fat trimming on physical composition. Fat content of marketable beef has decreased notably since the 1930s, and beef from the South African Bonsmara breed contains less than 10g lipid per 100g after trimming of subcutaneous fat, irrespective of age. Removal of all visible fat reduces the lipid content to less than 5g per 100g, comparing favourably with other lean animal products.

Consumo alimentar residual e sua relação com medidas de desempenho e eficiência e características in vivo da carcaça de cordeiros

Avaliou-se o consumo alimentar residual (CAR) e a conversão alimentar (CA) de 20 cordeiros, com o objetivo de estimar as correlações entre essas variáveis com medidas de desempenho e com características in vivo da carcaça. Os animais tiveram o consumo de MS (CMS) mensurado por 65 dias e foram pesados a cada 13 dias para obtenção do ganho médio diário (GMD). Foram considerados o peso vivo inicial (PVI), o peso vivo final (PVF), o peso metabólico (PM), o GMD, a taxa de crescimento relativo (TCR), a taxa de Kleiber (TK), a CA, o CMS e o CMS em percentual do PV (CMSPV). As avaliações de carcaça foram realizadas por ultrassom. O CAR se mostrou correlacionado com o CMS (+0,81), o CMSPV (+0,90) e a CA (+0,63). Correlações significativas foram encontradas entre CA e GMD; CA e TCR; CA e TK; e CA e PVI (-0,63, -0,74, -0,75 e +0,51, respectivamente). O CAR e a CA não se mostraram correlacionados com características de carcaça, e, da mesma forma, não houve diferença entre as classes de CAR para essas variáveis. Confirmou-se o potencial do CAR como medida de eficiência alimentar para cordeiros em confinamento, sem existência de relações com o ganho de peso e o tamanho corporal e sem alterações na composição da carcaça.

Effect of ß-Mannanase on Broiler Performance and Dry Matter Output Using Corn-Soybean Meal Based Diets

3 Abstract: The effect of a commercial beta-Mannanase enzyme (CTCZYME; CTC Bio Inc., Seoul, Korea) on broiler performance and dry matter output in corn-soybean meal diets was investigated. One hundred and twenty one-day-old male chicks of a commercial broiler strain were fed for 19 d on a nutritionally adequate diet based on corn and soybean meal. At that time birds were randomly allocated to four treatments, each of which had six replicates of five birds each. Aliquots of the basal diet were supplemented with four levels of the CTCZYME: 0%, 0.025%, 0.05% (recommended level) and 0.1%. Chromic oxide was used as a n indigestible marker. After eight days of acclimation excreta was collected daily, weighed and dried at 130°C for 24 h to obtain the dry matter output. After seven days of excreta collection the birds were weighed and the experiment was terminated. There were no significant differences for body weight gain, feed conversion or feed intake. The addition of CTCZYME at the inclusion level of 0.05% and 0.1% significantly reduced (p<0.002) the daily dry matter excreta output per bird. Analysis of the excreta showed a reduction of th e nitrogen level as the level of CTCZYME increased, indicating an improvement in nitrogen utilization by the bird. Gross energy of the excreta decreased as the inclusion level of the enzyme increased. When the inclusion levels of the enzyme increased, calcium and phosphorus levels increased, possibly due to a concentration effect. Higher levels of chromium in the excreta were observed with the increment of th e enzyme, suggesting an improvement on the digestibility of the feed product of the effect of the beta- mannanase. These data indicate that nutrient digestibility is enhanced by the effect of CTCZYME. The reason for the increasing digestibility not affecting the broiler performance may be due to the short time the enzyme was included in the diet. Another possibility is that a change in carcass composition may have occurred; more protein could have been deposited on the carcass instead of fat when the enzyme was included but further studies are required to confirm this assumption. Also, it has to be taken into account that the dietary protein levels provided the needs for the bird and they probably did not need to assimilate the now more available amino acids due to the effect of CTZyme.

The effects of selection indices for sustainable hill sheep production on carcass composition and muscularity of lambs, measured using X-ray computed tomography

A multi-trait selection index designed to improve the overall economic performance of hill sheep, including both maternal and lamb traits, has been developed and tested in a selection experiment over 7 years. Two versions of the index were tested, with different economic weights applied to the traits, on two different hill farms: one version including maternal and growth traits; the other version with additional breeding goals of carcass weight, fatness and conformation scores. Responses to selection, using both versions of the index, suggest that improvements are being made in overall index score and lamb growth. This study investigated the indirect effects of these selection indices on lamb carcass composition and muscularity traits, as measured using X-ray computed tomography (CT) scanning. A total of 499 lambs from the two hill farms were CT scanned at weaning (approximately 120 days of age). Approximately half of the lambs from each farm were from the selection line (S, animals with highest index scores selected for breeding), while the other half were from a control line (C, animals with average index scores selected). Composition and muscularity traits were estimated on each lamb from CT data and differences between genetic lines investigated, within farm, using restricted maximum likelihood analyses, adjusting for either live weight or age. Results showed that the selection index without carcass traits produced lambs with carcass composition that was not significantly different to control lambs at a given live weight or age. Including carcass traits in the index resulted in lambs with no compositional differences (except for a slight increase in bone) at a set age compared with controls. At a given live weight however, selection lambs had less fat and lower carcass weights and killing-out percentage. Muscularity (3-D muscle shape) and muscle area shape (2-D) were not improved as a result of selection on either version of the index (including carcass weight and grades in the breeding goals or not) and, at a fixed live weight, muscularity in hind leg and lumbar regions tended to be higher in the C line. To accelerate changes in carcass composition and muscularity within the context of a multi-trait selection index for hill sheep, consideration should therefore be given to including objective CT-derived carcass traits in the index in addition to the Meat and Livestock Commission (MLC) carcass grades or ultrasound measurements.

Changes in carcass composition and meat quality when selecting rabbits for growth rate

Sixty rabbits from the 23rd generation (group S) of a line selected for growth rate were compared to sixty rabbits from the 7th generation of the same line (group C) to study possible relevant changes in carcass composition and meat quality due to the selection and the consequent decrease in degree of maturity at slaughter weight (2000 g). The only relevant changes in carcass composition were an increase in kidneys, liver and dissectible fat percentages and a decrease in meat to bone ratio of the hind leg. In m. Longissimus, group S had lower yellowness of the carcass and higher redness and yellowness of the meat. ICDH activity increased and the aldolase:ICDH ratio decreased. In the hind leg, group S had higher values of PUFA, PUFA/SFA ratio and n − 3 fatty acids.

Meat Production Characteristics of Black Bengal Goat

Black Bengal goat is primarily reared for meat, skin comes here as a by-product. The present trial describes the effect of age on different carcass characteristics of Black Bengal goats of either sex. A total of 61 Black Bengal goats of different age and sex groups were slaughtered. They were reared under semi-intensive management on milk alone or with concentrates (of 10.14 MJ ME and 10.48 g M/kg DM) and freshly cut Napier grass (2 MJ ME and 25 g CP/kg of fresh matter) that provides the estimated NRC (1981) requirement. The four age groups were: pre-weaned kids (0-90 day), post-weaned kids (91-180 days), growing (181-365 days) and adult (>365 days). Goats were slaughtered according to 'Halal' method by severing the major vessels of the throat by a transverse cut. Different slaughter parameters of Black Bengal goat can be best predicted from the equations as follows: live weight (kg)=0.801 (shoulder height (cm))-24.32, (r 2 =0.94); carcass weight (kg)=0.364 (height at hind legs (cm))-11.54, (r 2 =0.91); edible weight (kg)=0.623 (shoulder height (cm))-19.94, (r 2 =0.91) and saleable weight (kg)=0.701 (shoulder height (cm))-21.99, (r 2 =0.92). Live weight, carcass weight, edible weight and saleable weight of castrated goat at one-year onward ranges from 20-22, 9.4-10.5, 14-16 and 16.6-18.8 kg, respectively, which are about 80% higher than most of the reported observations on Black Bengal goat of same age and sex. Slaughter weight, warm carcass weight, edible weight and saleable weight increased curvilinearly with age of slaughter but not affected (p>0.05) by sex. However, linearity of the response curve of affect of age on mentioned parameters ends at around 9 months. Visceral fat as per cent of live weight increased curvilinearly with age and attain its maximum (about 6%) at about 500 days. However, linear part of the quadratic model ends at about 300 days when visceral fat content is about 4.8% of body weight. Blood and skin yield for one-year old male goat was 797 g and 1.61 kg, respectively. Absolute yield of blood and skin increased curvilinealry and attained maximum level at about 400 days (13.3 months). Average proportion of different carcass cut were - round 27%, rump 7%, loin 10%, ribs (6-12th) 14%, shoulder 21%, Neck 7%, chest 14%. Thigh and shoulder constituted about 48.3% of the cold carcass weight. Overall crude protein content of meat samples of different carcass cuts progressively decreased with age starting from 57 at 0-90 days to 58, 47 and 33 per cent, respectively at 91-180, 181-365 and >365 days, respectively. Overall meat fat content increased almost linearly from 11.1% during 91-180 days to 22.9 and 39.5% during 181-365 and >365days, respectively. Results from this trial suggest that both carcass yield and carcass composition changes with age; and sex have little or no effect on carcass yield and carcass composition. However, caution should be made in using second conclusion as there were few female animals slaughtered relative to the male. Optimum slaughter age for Black Bengal goat reared under semi-intensive management with adequate feeding and management would be about 9 months when their live weight, warm carcass weight, edible and saleable weight of carcass can be about 16.74, 7.28, 12.05 and 13.81 kg, respectively. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 6 : 848-856)

Changes in carcass composition with growth and the effect of feed type in lambs of two breeds and their cross

To enable producers to meet market requirements for lamb carcasses from the resources available, it is important to know how breeds differ in growth and development over time and how this is affected by feeding regime. The aims of this study were to explore the effect of diverse breed and feed types on carcass composition, growth and feed intake and investigate how these change during growth.

Changes in carcass composition with age in 16-26 month old Red Deer

Modern retailing of venison through supermarkets requires that the product be on the shelf for an extended period compared with the traditional short season in autumn/early winter. However, deer are highly seasonal animals and a range of strategies is needed to increase marketing opportunities for venison. One strategy utilizes extended winter daylength and high levels of nutrition to advance the slaughter season (Davies, 1995; Fisher et al., 1995). Another strategy is to adopt more natural, low input systems with reduced production costs, in which deer reach slaughter condition during their third summer at 22-26 months of age, but this needs full investigation. This study involved sequential slaughtering of deer to ascertain how rapidly carcass composition and meat quality changes over this period.

The Diurnal Rhythm of Energy Expenditure Differs between Obese and Glucose-Intolerant Rats and Streptozotocin-Induced Diabetic Rats

Otsuka Long Evans Tokushima Fatty (OLETF) rats were developed as a model of noninsulin-dependent diabetes mellitus (NIDDM) with mild obesity. Changes in carcass composition and in the daily profile of energy expenditure were examined before and after manifestation of diabetes (8 and 24 wk, respectively), and compared with the normal control Long Evans Tokushima (LETO) rats and streptozotocin (STZ)-induced diabetic LETO rats. OLETF rats had greater body weights than LETO rats and significantly greater absolute and relative fat weights. A diurnal rhythm of energy expenditure associated with two peaks was observed in LETO rats, but the two peaks were not apparent in OLETF rats at 24 wk of age. A diurnal rhythm associated with one peak was observed in STZ-induced diabetic LETO rats. Energy derived from fat constituted this peak; the pattern of the daily energy expenditure was significantly different from that of either nontreated LETO or OLETF rats at 24 wk of age. NIDDM in OLETF rats at 24 wk of age has only a small role in modification of the diurnal rhythm of energy expenditure, whereas STZ-induced diabetes significantly affected the rhythm.

The effect of restricted feeding on growth hormone (GH) secretory patterns in genetically lean and fat wether lambs

AbstractThe aim of this work was to determine whether developmental changes in growth hormone (GH) secretory patterns and carcass composition were influenced by nutrition and genotype in sheep. Four-month-old wether lambs from lean (low backfat), fat (high backfat) and control selection lines were nutritionally restricted to maintain a 28 kg live weight or given food ad libitum for 24 weeks. Plasma concentrations of GH and insulin-like growth factor 1 (IGF-1) were measured at predetermined times and carcass composition of the animals determined at the end of the trial.From week 3 on, restrictions in dry matter (DM) intake were observed as the ad libitum treatment group had a significantly greater intake than the restricted treatment group (7·70 v. 5·80 kg DM per week, s.e.d. = 0·81). Differences in live weight between the feeding treatments were significant (P &lt; 0·05) at week 9. The restricted feeding regime was associated with significant reductions in plasma levels of IGF-1 but had no effect (P &gt; 0·05) on carcass weight-adjusted carcass fat proportion at the close of the trial. The effect of food restriction on GH secretory patterns was variable. Although there was initially a suppression in mean plasma GH, there was subsequently significantly higher mean plasma GH in the restricted feeding treatment. Periodogram analysis indicated that both the absolute levels of GH and the GH secretory pattern were altered by restricted feeding. In all animals, mean and basal GH concentrations, as well as the frequency and amplitude of pulses, declined from February to March and then increased from May to July (P &lt; 0·001).DM intake and live weight did not differ (P &gt; 0·05) between genotypes, however the fat genotype had greater carcass fatness than lean or control genotypes (P &lt; 0·01). There were no consistent differences between genotypes in plasma IGF-1 concentrations. In the ad libitum treatment, the lean and control genotypes had higher plasma GH levels than the f at genotype but the pattern of GH release did not vary. Under restricted feeding, both the pattern and the level of plasma GH varied between genotypes.It is concluded that the developmental change in GH secretory patterns is affected by nutrition but not in a consistent manner. Although restricted feeding resulted in higher mean plasma GH concentrations later in the trial, this did not result in a change in carcass composition. The biological cues which lead to increased fat deposition in older lambs need further study but plasma GH levels may not he an important mechanism in this process.

Effect of parity number on growth pattern and carcass measurements of continental cross suckler cows under lowland conditions

The objective was to examine the effects of parity of cows at slaughter on the growth and development of the carcass, and changes in carcass composition in continental suckler cows in a lowland beef system.The experiment had a factorial design based on the factors : parity and level of finish. The parity treatments were parities: 0 (maiden), 1, 3 and 5. The levels of finish were medium (fat class 3) and high (fat class 4 L). A group of three Blonde d’Aquitaine AI sires was common to parities 1, 3 and 5. Mean lactation length was 163 days which was spent at pasture. Animals for the medium level of finish were slaughtered at the point of service (maiden heifers) or at weaning (parities 1, 3 and 5), while high finish animals all had an additional finishing period on a grass silage/concentrate diet. A total of 77 animals of ¾ Charolais genotype were slaughtered within the experimental design with approximately equal numbers of animals slaughtered within each treatment.

Overview of the effects of beta-adrenergic receptor agonists on animal growth including mechanisms of action.

The beta-adrenergic receptors (beta-AR) are present on the surface of almost every type of mammalian cell. These receptors are stimulated physiologically by the neurotransmitter, norepinephrine and the adrenal medullary hormone, epinephrine. There are three subtypes of beta-AR, namely, beta1-AR, beta2-AR, and beta3-AR; the pharmacological and physiological responses of an individual cell result from the particular mixture of the three beta-AR subtypes present on that cell. Species-specific structure (amino acid sequence) also causes modification of the function of a given beta-AR subtype. Knowledge of the beta-AR subtypes present in various cell types, coupled with knowledge of receptor structure (sequence), will allow an understanding of the complexity of physiological function regulated by beta-AR. Oral administration of some beta-AR agonists increases muscle and decreases fat accretion in cattle, pigs, poultry, and sheep. The large number of physiological functions controlled by beta-AR suggests that the mechanism(s) for the observed changes in carcass composition may be extremely complex. Any proposed mechanism must begin with the possibility of direct effects of the agonist on skeletal muscle and adipocyte beta-AR. However, many other mechanisms, such as modification of blood flow, release of hormones, or central nervous system control of feed intake may contribute to the overall effects observed with a given beta-AR agonist in a given species. Furthermore, the pharmacodynamic properties of a particular agonist are complex and expected to vary among species as well as within the same species at different ages or when fed different diets.

Interactions of dietary levels of protein and energy on fingerling snakehead, Channa striata

A 4 × 3 factorial experiment was conducted to determine the optimum protein to energy ( P E ) ratio for fingerling snakehead. Four crude protein levels and three energy levels at each protein level were utilized. Laboratory-made brown fish meal was used as the major source of protein in all the test diets. Each of the experimental diets was fed to triplicate groups of 15 fingerlings with an average individual weight of 12 g in 110-1 flow-through fibre blast tanks at 28 ± 2 °C, with 5.9 to 7.2 mg dissolved oxygen 1 −1. The diets were fed at a rate equalling 3 wet body wt% day −1 in two equal rations and adjusted weekly for 8-weeks. The highest growth was attained by fingerlings fed a 40% protein diet with a P E ratio of 90.9 mg protein kcal −1 digestible energy. A lower but not significantly different ( P > 0.05) growth response was attained by fingerling fed a 45% diet with a P E ratio of 93.8 mg kcal −1. Protein efficiency ratio (PER) was affected by the increase in energy level from 400 to 480 kcal 100 g −1 at all protein levels except 40% where a diet with energy 440 kcal 100 g −1 showed maximum PER value. The lowest feed conversion ratio (FCR) was obtained at an P E ratio of 90.9 mg protein kcal −1. Carcass moisture content was not affected by dietary P E ratio. Other changes in carcass composition due to the change in dietary P E ratio were not consistent. This study also indicated that a lipid level of 13% can be effectively utilized by snakehead fingerlings without any adverse effects.

Effects of programmed gain strategies on performance and carcass characteristics of steers.

In Trial 1, 161 Angus x Simmental crossbred steers (initial BW 305 +/- 1.0 kg) were used in a completely randomized design experiment to determine the effects of intake restriction and programmed gain on cattle performance and carcass composition and characteristics. Five feeding systems were tested using step-wise increases in programmed intake level. Initially steers were fed to gain 1.13 kg/d. Intake was then increased to achieve a gain of 1.36 kg/d. At the end of the feeding period, steers had ad libitum access to feed. Duration of intake restriction and the period of unrestricted intake was varied. Feeding steers at restricted intakes and then increasing daily gain by increasing feed intake using four different schedules all reduced (P < .05) daily feed intake and total feed intake compared with providing ad libitum access to feed throughout the trial. Furthermore, daily feed efficiency was increased (P < .05) by two of the feeding systems compared with offering ad libitum access to feed throughout the trial. The feeding system used did not affect (P > .10) quality grade of the carcasses. In Trial 2, 77 individually penned Angus x Simmental crossbred steers (initial BW 273 +/- 1.2 kg) were used to determine the effects of various feed intake restriction systems. For systems 1 through 4, multiple periods of restriction and realimentation were investigated; the duration and magnitude of restriction were varied. Feed intake was not restricted for steers in system 5. The feed restriction systems used in this experiment did not result in decreased total feed intake or changes in carcass composition as compared with offering ad libitum access to feed. Reducing total energy intake seems to be a prerequisite to altering feed efficiency of steers in limit-feeding systems.

Compensatory growth and carcass quality in growth-restricted and refed beef steers.

Beef steers were fed in two phases 1) to determine the relative importance of changes in DMI, gastrointestinal tract fill, energy expenditures, and composition of gain in the compensatory growth phenomenon, 2) to compare the effects of growth restriction due to ad libitum consumption of a low-energy (low-concentrate) diet to those of limited intake of a high-energy (high-concentrate) feed, and 3) to examine changes in carcass composition and quality resulting from different types of growth restriction. During the growing phase (237 to 327 kg), steers were fed either a high- (C) of low- (F) concentrate diet. Diet F was available for ad libitum consumption (FA) and diet C was available either for ad libitum consumption (CA) or on a limited basis (CL) to match the live weight gains by the FA group. During the finishing phase (327 to 481 kg), all steers received diet C, either for ad libitum consumption (CA) or restricted (CL) to 70% of the intake by the corresponding CA steers. Backfat thickness was markedly reduced (P < .001) by final feed restriction (7.4 and 6.9 mm for CL-CL and FA-CL respectively), compared with CA-CA (12.6 mm). Backfat also was lower in CL-CA (11.6 mm, P < .10) and FA-CA (9.9 mm, P < .05) than in CA-CA steers. Conversely, marbling scores were similar among groups, except for the FA-CL steers, which had lower marbling scores than FA-CA and CL-CA steers (P < .05). Higher DMI following growth restriction were accompanied by increased rates of live weight (+54 and +27%) and empty body weight (EBW; +57 and +43%) gain for CL-CA and FA-CA steers, respectively, compared with CA-CA steers. Gain:feed (EBW basis) were improved in some restricted/refed groups (+30, +13, and +10%, for Cl-CA, CL-CM respectively CA-CA. Increased DMI played a major role in the compensatory gain response in both CL-CA and FA-CA groups. Maintenance requirement was reduced (-17%) in CL-CA and increased in the FA-CA group (+21%); both changes affected the magnitude of compensatory gain in those animals. In contrast, composition of gain had little or no effect on the compensatory gain response. Programmed feeding can be used to manipulate carcass quality, but low-concentrate feeding during the growing phase may impair overall feedlot performance.