Improve Meat Production Research Articles

Effect of metabolic modifiers on meat quantity and quality

The inadequacy of food supply due to the population growth together with urbanization, drive a significant demand for animal sources. Consequently, a number of technologies have been developed and are being used commercially to enhance profitability of animal production and to improve their quality. The objective of this paper is to review recent studies on the effects of metabolic modifiers on quantity and quality of meat and their contribution in sustaining food security and improving quality of life. Metabolic modifiers such as β-agonists, anabolic implants, somatotropin, immunocastration, vitamin E, conjugated linoleic acid (CLA) and trace elements have been utilized by different agribusiness to improve meat production and enhance meat quality. These compounds supplement to the animals with feed, as an injection or implant to enhance the rate of gain, the feed utilization efficiency, carcass percentage, shelf-life of meat, improve meat’s nutrient content and/or meat palatability. On the other hand, some metabolic modifiers are either not approved or banned from use due to negative health effects to the consumer. There is a consistent research report for the approved technologies enhancing protein synthesis and muscle deposition, while decreasing fat synthesis and deposition, when they are applied in the recommended dosage. Therefore, we believe that utilizing available technologies and methodologies in reference to the mentioned materials will help in improving meat quality and thereby increase productivity of the livestock resource and hence, improve food security. Key words: Meat yield, food security, beef, lamb, pork.

Effects of outdoor housing of piglets on behavior, stress reaction and meat characteristics.

Well-designed housing systems are important from the viewpoint of animal welfare and improvement of meat production. In this study, we investigated the effects of outdoor housing of pigs on their behavior, cortisol levels, and meat characteristics. Two groups that were born and raised in a spacious outdoor pen (4×10 m for every two sows) or a minimum-sized standard pen in a piggery (1.9×2.2 m for every sow) were studied. When their behaviors at the age of 2 to 3 wk were observed, the number of rooting episodes tended to be larger (p = 0.0509) and the total time of rooting tended to be longer (p = 0.0640) in the outdoor-housed piglets although the difference was not significant. Basal salivary cortisol levels of the outdoor piglets at the age of 4 wk were significantly lower than those of the indoor piglets (5.0±0.59 ng/ml vs. 11.6±0.91 ng/ml, 30 min after treatment), although their plasma cortisol levels were similar (53.3±3.54 ng/ml vs. 59.9±4.84 ng/ml, 30 min after treatment). When the ears were pierced at weaning, plasma and salivary cortisol levels were increased in both groups, even at 15 min after piercing. However, the increase in the outdoor-housed group was significantly less than that in the indoor-housed group. Throughout their lives, body weight and daily gain of the pigs were not significantly different between the two groups. In a meat taste preference test taken by 20 panelists, saltiness, flavor, and color of the outdoor-housed pork were found to be more acceptable. Moreover, when an electronic taste-sensing device was utilized, the C00 and CPA-C00 outputs (3.78±0.07 and −0.20±0.023), which correspond to compounds of bitterness and smells, respectively, were significantly lower in the outdoor-housed pork (5.03±0.16 and −0.13±0.009). Our results demonstrate that the outdoor housing system for piglets induces natural behaviors such as rooting and suppresses the strongest stress reaction of piglets, which could be important for animal welfare. Moreover, the outdoor housing system might change muscle characteristics and improve pork bitterness, flavor, and color. These changes may be preferred by consumers, increasing the sale of these meats.

Identification of C127G point mutation in growth hormone (GH1) gene in indigenous breeds' cattle.

The bovine growth hormone (bGH) is well known in that it plays an important role in biological processes such as mammary development, lactation, ageing, growth and metabolism regulation. For this reasons bGH can be used as a candidate gene marker for improving meat and milk production. The aim of the present study was to test the presence of bGH- Alu I polymorphism, consisting in C-G point mutation, in indigenous breeds cattle.

Meat Science and Muscle Biology Symposium: stem cell niche and postnatal muscle growth.

Stem cell niche plays a critical role in regulating the behavior and function of adult stem cells that underlie tissue growth, maintenance, and regeneration. In the skeletal muscle, stem cells, called satellite cells, contribute to postnatal muscle growth and hypertrophy, and thus, meat production in agricultural animals. Satellite cells are located adjacent to mature muscle fibers underneath a sheath of basal lamina. Microenvironmental signals from extracellular matrix mediated by the basal lamina and from the host myofiber both impinge on satellite cells to regulate their activity. Furthermore, several types of muscle interstitial cells, including intramuscular preadipocytes and connective tissue fibroblasts, have recently been shown to interact with satellite cells and actively regulate the growth and regeneration of postnatal skeletal muscles. From this regard, interstitial adipogenic cells are not only important for marbling and meat quality, but also represent an additional cellular component of the satellite cell niche. At the molecular level, these interstitial cells may interact with satellite cells through cell surface ligands, such as delta-like 1 homolog (Dlk1) protein whose overexpression is thought to be responsible for muscle hypertrophy in callipyge sheep. In fact, extracellular Dlk1 protein has been shown to promote the myogenic differentiation of satellite cells. Understanding the cellular and molecular mechanisms within the stem cell niche that regulate satellite cell differentiation and maintain muscle homeostasis may lead to promising approaches to optimizing muscle growth and composition, thus improving meat production and quality.

Body measurements and morphological indexes of a cattle population in the Adamawa region (Cameroon)

Growing population and urbanisation in Central and West Africa lead to an increasing demand for meat and milk products. The improvement of cattle production might cover these needs for human consumption (de Haan, 2001). Mass selection is the first step to develop animal production, where genealogical information might not be available, above all to improve meat production. Body measurements at the end of growth, may be useful as selection criteria (Maiwashe et al., 2002) for performance traits, which have medium and high heritability (Gilbert et al., 1993)....

Research on the improvement of the meat production in the romanian Teleorman Black Head sheep by crossing with meat breeds

In Romania the main direction of sheep breeding was until two decades ago, wool production, while the milk and meat productions were left in the background. After the 1990s, particularly after the accession of Romania to the European Union, sheep production redirected toward milk and meat production focusing on the identification of the most adequate techniques to increase these productions. One solution to restore this sector is to produce suckling lambs or fat lambs, competitive on the foreign markets. Within this context, the objective of our paper, part of a larger program, is to use industrial crosses to improve meat production in the local sheep breeds. We present here the results of crossing the local Teleorman Black Head (TBH) with imported meat rams: Suffolk and German Black Head (GBH). The studies monitored the performance of the (milk) hybrids F1 compared to the local breed lambs. 60 lambs assigned to three groups (20 lambs per group) were weaned at 2 months, when control slaughtering was used to determine: the slaughter house and commercial yield, proportion of carcass parts, proportion of butchery parts, meat to bone ratio for each part, carcass measurements, chemical composition of the meat, fatty acids and cholesterol included. At birth, the local breed lambs had 4.77 kg and a gain of 0.253 kg and reached 18.31 kg at slaughter. GBH hybrids lambs weighed 4.76 kg at birth, a gain of 0.277 kg and reached 20.63 kg at slaughter; Suffolk hybrids lambs weighed 5.36 kg at birth, 0.322 kg daily weight gain and 24.92 kg at 2 months. The slaughterhouse yield, the meat to bone ratio and carcass dimensions were better in the hybrids than in the local breed. The Suffolk and German Black Head rams transmitted to their progeny a higher speed of growth, a conformation specific to the meat breeds and a better dressing in muscles, a higher slaughter yield and a better meat to bone ration than the local breed lambs.

Overview of current meat hygiene and safety risks and summary of recent studies on biofilms, and control of Escherichia coli O157:H7 in nonintact, and Listeria monocytogenes in ready-to-eat, meat products

As meat consumption is increasing around the world, so do concerns and challenges to meat hygiene and safety. These concerns are mostly of a biological nature and include bacterial pathogens, such as Escherichia coli O157:H7, Salmonella and Campylobacter in raw meat and poultry, and Listeria monocytogenes in ready-to-eat processed products, while viral pathogens are of major concern at foodservice. A major goal of scientists, industry, public health and regulatory authorities is to control pathogenic microorganisms and improve meat product hygiene and safety within a country and internationally. This paper is not a comprehensive or critical review of the scientific literature on the broad area of meat hygiene and safety, but it provides an overview of major current meat hygiene and safety issues, and then a summary of studies on biofilm formation by pathogens, control of E. coli O157:H7 in nonintact meat products, and control of L. monocytogenes in ready-to-eat meat products, conducted at the Center for Meat Safety & Quality and Food Safety Cluster of Colorado State University in recent years.

Feed restriction and genetic selection on the expression and activity of metabolism regulatory enzymes in rabbits

This work aims at the identification of relevant intermediate metabolism enzymes contributing to improved meat production due to genetic selection. A wild rabbit (WR) breed and a highly meat selected breed (New Zealand (NZ) rabbit) were used. Food restriction was used as an experimental condition so as to enhance differences within the metabolic pathways under study. During a period of 30 days, NZ and WR experimental breeds were subjected to, respectively, 40% and 60% ad libitum food restriction leading to 17.7% and 21.1% initial weight. Hepatic glycolytic, lipidic and protein regulatory enzyme activity, transcriptional and metabolite levels were determined. Insulin-like growth factor (IGF-1), triiodothyronine, and cortisol were also evaluated. In the glycolytic pathways, the NZ control rabbits presented a higher phosphofructokinase and pyruvate kinase activity level when compared to the WR, while the latter group showed a higher expression of glycogen synthase, although with less glycogen content. In the nitrogen metabolism, our results showed a lower activity level of glutamate dehydrogenase in WR when subjected to food restriction. Within the lipid metabolism, results showed that although WR had a significantly higher mRNA hepatic lipase, non-esterified fatty acid levels were similar between the experimental groups. NZ rabbits presented a better glycemia control and greater energy substrate availability leading to enhanced productivities in which triiodothyronine and IGF-1 played a relevant role.

Comparison of a modern broiler line and a heritage line unselected since the 1950s

Selecting chicken for improved meat production has altered the relative growth of organs in modern broiler lines compared with heritage lines. In this study, we compared the growth and feed efficiency of a heritage line, UIUC, with a modern production line, Ross 708, for 5 wk posthatch. During this period, the BW and feed efficiency of the modern strain was higher than that of the heritage line, indicating that the Ross 708 birds were more efficient than the UIUC birds at converting feed to body mass. The relative growth of the breast, heart, liver, and intestine were also compared during these 5 wk. The breast muscle of the heritage line constituted 9% of the total body mass at 5 wk, whereas in the modern line, the breast muscle was 18% of the total mass of the bird. In contrast, the relative size of the heart decreased after d 14 in the modern line, suggesting that selection for increased breast muscle has translated into relatively less weight of the heart muscle. The liver matured earlier in modern lines, possibly improving nutrient utilization as the birds shift from lipid- to carbohydrate-rich feed. Finally, jejunal and ileal sections of the intestine were 20% longer in the modern line, perhaps allowing for increased nutrient absorption.

Relationship Between Some Serum Enzyme Activities, Liver Functions and Body Weight in Growing Local Chickens

2 Abstract: An experiment was conducted to detect the relationship between some serum enzyme activities, i.e. lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) enzymes and liver functions, as well as evaluating the difference in some physiological parameters in relation to body weight in six body weight lines of Golden Montazah (GM) chickens. A total of 288 GM chickens 4-wk old were selected from 500 unsexed GM chickens and divided into six lines (three lines within each sex) heavy (HL), light (LL) and control (CL) according to their body weights. Each line was represented by 3 replicates (16 chicks each) over two generations (G and G ). Live body weight (LBW), body weight gain (BWG), mortality rates and the levels of 0 1 some serum parameters, i.e. total protein (TP), triiodothyronine (T ), LDH, CPK, aspartate aminotransferase 3 (AST) and alanine aminotransferase (ALT) were determined at 4 WOA in G and at 12 WOA in G and G. The 0 0 1 results showed that the average LBW and BWG for heavy lines and males were significantly (p<0.01) higher than that of light lines and females, respectively. The heavy line chicks recorded the lowest mortality rate compared to the light ones during the period from 4-12 WOA over the two generations. The HL body weight was associated generally with an increase in the serum TP, T level and LDH activity and a decrease in AST, 3 ALT and CPK activities as compared with the LL body weight. Converse trend was observed for these traits with the LL chicks. These results concluded that, it is possible to use these parameters as physiologica l indices to attain the goal of improving meat production and to produce a safety and healthy poultry production.

Effects of concentrate levels on fattening performance, carcass and meat quality attributes of Small East African × Norwegian crossbred goats fed low quality grass hay

To assess the effects of finishing Small East African × Norwegian crossbred goats with concentrate diets on the fattening performance, carcass and meat quality, 32 castrated crossbred goats (9.5 months old, 17.1 kg BWT) were equally allocated into four levels of concentrate supplementation. The concentrate levels were: Zero access to concentrate (T0), 33% access to ad libitum concentrate allowance (T33), 66% access to ad libitum concentrate allowance (T66) and 100% access to ad libitum concentrate allowance (T100). Each animal had access to ad libitum grass hay. Ad libitum concentrate intake for the goats was 663 g/d, which supported ME intake of 8.7 MJ/head/d. The attained maximum daily gain was 96 g/d. T100 and T66 goats were comparable in slaughter weight but the former had 2 kg heavier ( P < 0.05) carcasses than the latter. T100 and T66 goats were similar in carcass fatness scores, though both were fattier ( P < 0.05) than other diet groups. Dressing percentage (DP) was expressed in three different ways. In all but commercial DP, T100 were comparable to T66 goats, but all were higher than the other diet groups. For T0 goats, pH-values remained above 6 even after 24 h post-mortem. Cooking losses increased ( P < 0.05) with increasing levels of concentrate supplementation. Moreover, among the muscles assessed, M. rectus abdominis had the least cooking loss. Warner–Bratzler shear force values of cooked muscles were highest ( P < 0.05) in M. gluteobiceps, followed by M. vastus lateralis, while M. psoas major and longismus dorsi aged for 6 days had the least values. Finishing Small East African × Norwegian crossbred goats at 66% access to their ad libitum concentrate intake gives optimum carcass and meat quality, and that any increase above this level seems not to improve meat production.

Genetic improvement of wool production in Spanish Merino sheep: genetic parameters and simulation of selection strategies

Wool production of the Spanish Merino breed was analysed after several decades of genetic selection to improve meat production. Genetic parameters (heritability and correlations) were estimated for greasy fleece weight, staple length, crimp frequency and fibre diameter of 1869 Spanish Merino purebred sheep. Heritabilities ranged from 0.08 ± 0.050 (fibre diameter) to 0.22 ± 0.060 (staple length), and the genetic correlations ranged from –0.63 ± 0.159 (crimp frequency – staple length) to 0.75 ± 0.222 (fibre diameter – staple length). Genetic simulations were developed to show the consequences of eight selection strategies, which included single trait selection on wool traits and liveweight (the current selection criteria) and index selection combining traits. The results show that it is possible to improve wool and growth traits at the same time. Also, our results show there is indirect genetic progress for wool characteristics using the current liveweight selection criterion.

Desempenho produtivo e custos com alimentação de novilhos bubalinos alimentados com dietas com diferentes fontes de lipídeos

O objetivo neste trabalho foi avaliar o ganho de peso, a conversão alimentar e os custos com alimentação de novilhos bubalinos em sistema de confinamento. Utilizaram-se 13 bubalinos Murrah castrados (peso vivo médio inicial de 297±9 kg) alimentados com três diferentes dietas (tratamentos): sem lipídeo adicional; óleo de soja; e grão de soja integral. A duração do experimento foi de 84 dias, divididos em três períodos de coleta, cada um com 28 dias. Nos seis últimos dias de cada período, foram coletadas amostras de alimentos, sobras e fezes para determinação do consumo. As dietas foram fornecidas duas vezes ao dia (às 8 e 16h), na forma de ração total, em quantidade ajustada para ocorrer 10 a 20% de sobras. Os animais foram pesados no início do experimento e ao fim de cada período experimental, após jejum de 16 horas. Os ganhos médios diários foram de 990, 1.090 e 1.280 g/dia para os animais alimentados com as dietas sem lipídeo adicional, com grão de soja e com óleo de soja, respectivamente. As conversões alimentares foram melhores nos animais alimentados com a dieta contendo óleo de soja. O custo da dieta com grão de soja foi maior que o das demais. O melhor desempenho e a melhor resposta econômica foram obtidos quando fornecida a dieta com óleo de soja, o que torna viável sua utilização no confinamento de bubalinos.

Effects of Adequate or Marginal Excess of Dietary Methionine Hydroxy Analogue Free Acid on Growth Performance, Edible Meat Yields and Inflammatory Response in Female Broiler Chickens

Two experiments were conducted to determine the effects of adequate or marginal excess of dietary DL-2-hydroxy-4-(methylthio) butanoic acid (MHA) on productive performance and inflammatory response induced by E. coli lipopolysaccharide (LPS). In first experiment, day-old-female chicks (Ross strain) were provided for 48 days with four experimental diets; (1) AB diet: a diet with antibiotics (AB) and DL-methionine (DLM) to meet the total sulfur amino acid (TSAA) requirements of broiler chickens, (2) DLM diet: the first diet without AB, (3) MHA diet: a diet supplemented with MHA in place of DLM of the diet 2 to meet the TSAA requirement, (4) excess MHA diet: a diet with 1.6 folds higher than the content of MHA in the MHA diet. All diets were formulated with ingredients of plant origin. There was no difference in growth performance among the dietary treatments. Edible meat yields in chicks fed the excess MHA diet were better than that in chicks fed the DLM or MHA diet. Chicks fed the excess MHA or MHA diet showed lower plasma ceruloplasmin and alpha-1 acid glycoprotein concentration following LPS injection than those fed the DLM diet at 23 days of age. The concentrations in chicks fed the excess MHA diet were comparable to those chicks fed the AB diet. In second experiment, 7-days -old female chicks were fed either of the DLM or MHA diet for 14 days. Chicks fed the MHA showed higher excreta dry matter content than chicks fed the DLM diet. Heterophil to lymphocyte ratio in blood after LPS injection was lower in chicks fed the MHA diet than that in chicks fed the DLM diet. These results suggest that marginal excess supplementation of MHA, in place of DLM, to diet improved meat production in female broiler chicks and dietary MHA has potential to alleviate certain stress responses.

Bos indicus type of growth hormone receptor gene is retained in Japanese Black cattle

The growth hormone receptor (GHR) gene is responsible for growth and carcass traits, and polymorphisms associated with the variation of meat production are thought to occur in the liver-specific promoter of the GHR gene in cattle. The aim of this study was to analyse the structure of the liver-specific promoter of GHR in Japanese Black cattle, as the relationship between GHR polymorphism and meat production is poorly understood in this breed. Typically in European cattle, the LINE-1 element, a family of retrotransposons, is inserted in the liver-specific promoter. However, a short GHR promoter without the LINE-1 sequence was found in the Japanese Black breed as in Bos indicus cattle. The frequency of the short allele was approximately 60%. In addition, 24 of 29 Holstein/Japanese Black crosses carried the short allele from their sire. The present result suggests that the short allele for GHR may be a candidate marker for improving meat production of Japanese Black cattle.

사료의 조단백질 수준이 육성기 흑염소의 발육과 육질에 미치는 영향

본 시험은 사료의 조단백질 수준이 육성기 흑염소의 발육과 육질에 미치는 영향을 구명하기 하기 위하여 흑염소 육성축 수컷 40두를 공시하여 조단백질 수준을 각각 달리하여 2004년 4월 19일부터 2004년 9월 13일까지 시험을 실시하였으며 그 결과는 다음과 같다. 일당증체량은 CP 14%, CP 18%구가 각각 84.0, 83.0g으로 CP 12%구 69.2g 보다 높았으며(P<0.05) CP 16%구는 80.9g으로 비슷한 경향이었다. 1일 사료섭취량은 농후사료와 볏짚 각각 590g, 45g 내외로 처리구간에 비슷하였고 증체 g당 사료요구율은 CP 14%, 16%, 18%구간에는 7.0-7.3으로 비슷하였으나 CP 12%구는 다소 높은 경향이었다. 도체율은 CP 12%구가 61.7%로 CP 14와 CP 18%구 보다 높았으나(P<0.05) CP 16%구와는 비슷하였다. 정육율은 CP 16%가 51.7%로 CP 12와 CP 14%구 보다 높았다(P<0.05). 지방율은 CP 12%구가 12.8% 높았으며(P<0.05) 뼈율은 17.0% 내외로 처리구간에 비슷하였다. 고기의 물리적 특성인 전단력과 가열 감량은 CP 16%구와 CP 14%구가 다른 처리구보다 다소 낮은 경향이었고 보수력은 CP 16%구가 CP 18%구 보다 높았다(P<0.05). 관능검사결과 다즙성은 CP 16%구가 CP 12%구 보다 우수하였으며(P<0.05) 연도도 다른 처리구에 비해 우수한 경향이었다. 이러한 결과를 종합적으로 고려할 때 육성기 흑염소의 발육과 육질개선을 위한 사료의 적정 조단백질 수준은 14-16%가 적합한 것으로 사료된다. This study was conducted to investigate the optimal CP level in growing goat kids. Forty male goats were divided into four treatment groups fed diets containing CP 12, 14, 16, and 18% of concentrate feed, and rice straw, respectively. Results are summarized as follows. Average daily gain’s(ADG) of groups fed diets with CP 14% and CP 18% were 84.0 and 83.0g/d each, which were higher than group fed diets with CP 12% grown at 69.2g of ADG(P<0.05). Daily feed intakes of concentrate and rice straw were 590g and 45g each and there was no difference found between treatments. The amounts of feed required for body weight gain(g) were similar in the range of 7.0-7.3 for groups fed diets with CP 14%, 16% or 18%. But the group fed diets with CP 12% required somewhat more feed for gain at 8.8g. Dressing percentage of groups fed diet with CP 12% was 61.7%, which was higher than groups fed diets with CP 14% or CP 18%(P<0.05) but similar to that fed diet with CP 16%. Meat percentage from goats fed diet with CP 16% was 51.7%, which were higher than goats fed diets with CP 12% or CP 14%(P<0.05). Fat deposition of CP 12% group was higher than the other groups(P<0.05). Percentage of bone weight averaged 17.0% without any difference among treatment groups. Shear force and cooking loss, which are physical properties of goat meats, were lower in CP 16% and CP 14% groups than the other two groups. Water holding capacity of goats meats from CP 16% was higher than those from CP 18% group(P<0.05). Results from panel test showed that juiciness of meats from CP 16% group was higher than those from CP 12% group(P<0.05). Meats from CP 16% also was tested to be more tender than meats from the other groups. Results from this work suggest that the optimum crude protein level in growing goat's concentrate is 14-16% and that increase above this level seems not to improve meat production.

Genetic correlation between serum insulin-like growth factor-1 concentration and performance and meat quality traits in Duroc pigs.

This study was intended to examine whether serum IGF-I concentration is appropriate for use as a physiological predictor for genetic improvement of meat production and meat quality traits in pigs. Heritabilities and genetic correlations were estimated for these traits. The Duroc breed used in this study was selected for seven generations for average daily BW gain (DG) from 30 to 105 kg of BW, loin-eye muscle area (EM), backfat thickness (BF), and intramuscular fat (IMF) content. Serum IGF-I concentration of boars and gilts at the fourth generation of selection and that of boars, gilts, and barrows from the fifth to seventh generations of selection were measured at 8 wk (IGFI-8W) for 832 animals and again at the time they reached 105 kg of BW (IGFI-105KG) for 834 animals. A multivariate REML procedure was used to estimate genetic parameters with a model incorporating generation of selection, sex, common environmental effect of litter, and individual additive genetic effects. Heritability estimates for IGFI-8W and IGFI-105KG were 0.23 +/- 0.02 and 0.26 +/- 0.03, respectively. The estimates of common environmental effect for IGFI-8W and IGFI-105KG were 0.20 +/- 0.02 and 0.03 +/- 0.01, respectively. Positive genetic correlations were estimated between IGFI-8W and DG (0.26 +/- 0.08), EM (0.22 +/- 0.10), and IMF (0.32 +/- 0.10). Moreover, the positive genetic correlation between IGFI-105KG and EM was 0.42 +/- 0.08. These results indicate that serum IGF-I concentration at an early stage of growth was effective for prediction of IMF, but it was not a reliable physiological predictor of genetic merit of meat production traits.

The effect of dietary crude protein level on growth, carcass and meat composition of male goat kids in Tunisia

Effects of concentrate protein content on growth performances and body composition were studied on fifteen local goat kids. All kids were male with an average body weight of 23.3 kg (S.D.=2.1 kg) at the beginning of the experiment. Animals were randomly divided into three groups of five kids each. Goats in each group received individually oat hay ad-libitum and one of three concentrates containing low, medium or high crude protein level. Low, medium, and high crude protein levels were 100, 130, and 160 g/kg of dry matter, respectively. All concentrates were isocaloric. The growth experiment lasted 12 weeks. In the following 2 weeks, digestibility was measured and then all kids were slaughtered. During the first 6 weeks of the experiment, kids fed low and medium crude protein diets gained less weight ( P<0.05) than those fed the highest protein level. In the rest of the experimental period, animals receiving the medium diet had the highest growth rate ( P<0.05). Digestibility of dry matter, organic matter, and crude protein was similar for the high and medium protein diets and was higher ( P<0.05) than that for the low diet. This same trend was found for the nitrogen balance except for the nitrogen retention. Diet content in crude protein seemed not to affect empty body and carcass weights, dressing percentage, and external (skin, head and feet) and thoracic organs (lungs and heart). However, goats fed medium protein level had the heaviest ( P<0.05) liver and gut among all animals. Muscle, bone and adipose tissue mean weights did not follow the increase of crude protein level in the diet. However, animals given medium crude protein diet had relatively more muscle ( P<0.01) and less fat ( P<0.05) than those fed high diets. Bone proportion was comparable among animals receiving the three diets. Animals fed high protein diet had more omental and mesenteric fat ( P<0.05) and total body fat in absolute ( P<0.05) and relative value ( P<0.01) than those offered the medium level, while values found for the low diet kids were intermediate. Meat of kids receiving the medium diet crude protein level was juicier than meat from other kids. It contented more protein ( P<0.05) and less fat ( P<0.01). Results from this work suggest that the optimum crude protein level in growing goats’ concentrate is approximately 130 g/kg DM and that any increase above this level seems no to improve meat production.

Prediction of the air velocity field in modern meat dryers using unsteady computational fluid dynamics (CFD) models

To even out drying conditions and thereby improve meat product processing, modern dryers run with a ventilation cycle, during which, while the total airflow rate remains steady, the airflow rate ranges reciprocally from a low to a high level in each of two blower ducts located on either side of the plant. In this work, using a two-dimensional computational fluid dynamics model with time-dependent boundary conditions (i.e. an unsteady model), the homogeneity of the distribution of the air velocity in an industrial meat dryer is discussed for several low and high levels of the ventilation cycle, and two forms of this cycle (linear and sinusoidal). The changes in the airflow structure due to dissymmetry occurring in the ventilation cycle are also evaluated. All airflow simulations are consistent with the heterogeneity of drying usually observed in practice. This work can provide professionals with a rational approach to help them in the operation and design of modern dryers.

Genetic parameters for meat quality and carcass traits and their correlation with wool traits in Australian Merino sheep

Estimates of genetic parameters for carcass traits in Merino sheep are presented, including muscle pH and colour, which are indicators of meat quality. The inclusion of these in the parameter set for genetic evaluation will provide the basis for more accurate estimated breeding values and the design of better breeding programs for improving meat traits in straightbred Merino sheep and crossbred lamb production. Data from 1045, nineteen-month-old Merino rams, the progeny of 125 sires from 3 strains that are representative of the industry, were used. Heritability and genetic correlations were estimated by fitting an animal model using a REML procedure in univariate and multivariate analyses. The traits included fasted pre-slaughter liveweight; dressing %; carcass tissue depth at the GR site (FATGR); fat depth at the C site (FATC); eye muscle depth (EMD), width (EMW), and area (EMA); ultimate pH and colour (L*, a*, b*) of the eye muscle. Multivariate analyses were used to estimate genetic correlations among meat traits and between wool traits (clean wool weight and mean fibre diameter) and selected carcass and meat traits. Estimates of heritability were: liveweight 0.51 (±0.10), dressing % 0.39 (±0.10), FATGR 0.33 (±0.09), FATC 0.20 (±0.08), EMD 0.27 (±0.08), EMW 0.15 (±0.07), EMA 0.23 (±0.08), muscle pH 0.27 (±0.09), and 0.14 (±0.07), 0.02 (±0.06), and 0.04 (±0.06) for the meat colour measurements L*, a*, and b* respectively. There was a favourable genetic correlation between muscle pH and colour L* of –0.56 (±0.23). There were also significant genetic correlations between wool weight and FATGR (–0.34 ± 0.16) and between mean fibre diameter and muscle colour L* (–0.66 ± 0.27). The study indicates that there is genetic variation for carcass traits, including indicators of meat quality, with scope for selection to improve meat production and quality in Merino sheep.