Supplementation of Acacia dealbata versus Acacia mearnsii leaf-meal has potential to maintain growth performance of lambs grazing low-quality communal rangelands in South Africa.

Supplementing livestock grazing communal rangelands with leaf-meals from Acacia trees, which are currently considered as problematic invasive alien plants globally, may be a sustainable way of exploiting their desirable nutritional and anthelmintic properties. The current study evaluated worm burdens and growth performance of lambs grazing low-quality communal rangelands supplemented with leaf-meals prepared from the invasive alien plant species; Acacia mearnsii or A. dealbata. Forty, three-month-old ewe lambs weighing an average of 18.9 ± 0.60 kg were randomly allocated to four supplementary diets: (1) rangeland hay only (control), (2) commercial protein supplement plus rangeland hay, (3) A. mearnsii leaf-meal plus rangeland hay and (4) A. dealbata leaf-meal plus rangeland hay. All the supplementary diets were formulated to meet the lambs' minimum maintenance requirements for protein. All the lambs were grazed on communal rangelands daily from 0800 to 1400 after which they were penned to allow them access to their respective supplementary diets until 08:00 the following morning. The respective supplementary diets were offered at the rate of 400 g ewe- 1 day- 1 for 60 days. Lambs fed the commercial protein supplement had the highest dry matter intake followed by those fed the Acacia leaf-meals and the control diet, respectively (P ≤ 0.05). Relative to the other supplementary diets, lambs fed the commercial protein supplement and A. dealbata leaf-meal had higher (P ≤ 0.05) final body weight and average daily gains. Dietary supplementation did not affect lamb faecal worm egg counts over the study period (P > 0.05). There was no association between supplementary diets and lamb FAMACHA© scores (P > 0.05). It was concluded that supplementation of Acacia dealbata versus Acacia mearnsii has the potential to emulate commercial protein in maintaining growth performance of lambs grazing communal rangelands in the dry season.

Meat quality, skin damage and reproductive performance of ostriches exposed to extensive human presence and interactions at an early age.

The effect human presence and interactions performed after hatch to 3 months of age has on ostrich meat quality, skin damage and reproductive performance at a later age was investigated in 416-day-old ostrich chicks. The chicks were allocated to one of the three treatments, which varied with regard to exposure to human presence and care for 3 months post-hatch: HP1-extensive human presence with physical contact (touch, stroking), gentle human voice and visual contact; HP2-extensive human presence with gentle human voice and visual contact without physical contact; S-standard control treatment, where human presence and visual contact were limited to routine management, feed and water supply only. Carcass attributes (carcass weight, dressing percentage and drumstick weight), meat quality traits (pH, colour and tenderness) and skin traits (skin size, skin grading and number of lesions) were evaluated on twenty-four 1-year-old South African Black (SAB) ostriches. Reproductive performance (egg production, average egg weight, number of clutches, clutch size, chick production, average chick weight, fertility and hatchability percentage) were recorded for the first three breeding seasons of 23 SAB pair-bred females from this study. No differences in carcass attributes, meat quality, skin traits and reproductive performance were found between treatments (P > 0.05). It was evident that exposure of day-old ostriches to extensive human presence and interaction as chicks did not influence carcass attributes, meat quality or skin traits at slaughter age, but more importantly, it did not compromise their reproductive performance.

Limitations and prospects of improving beef cattle production in the smallholder sector: a case of Limpopo Province, South Africa.

The opportunity for the smallholder beef farming system to support the growth of South Africa's livestock industry is untapped. Slow growth of the sector is attributed to many limitations that affect the smallholder beef farming sector. The objectives of the current study were to identify and characterize the systemic challenges and constraints that confront market-oriented smallholder beef farmers in the Limpopo Province, South Africa. Data collection involved interviewing all the 62 farmers under the Limpopo Industrial Development Corporation (IDC)-Nguni project using structured questionnaires. The sample was predominantly males (87%) and adults aged over 45 years (88%). Close to half (47%) of the respondents had tertiary education. Major ecological and production challenges reported as percentages of respondents were drought (96%), rangeland degradation (94%), diseases (89%), feed shortage (86%), and inadequate water (82%). Nearly 50% of the respondents ranked the extent of these challenges as high to very high. Results indicated that poor access to finance, lack of infrastructure, and poor access to markets were some of the key limitations reported by more than 80% of the respondents with above 50% ranking them as high to very high. Logistic regression models showed that respondents' perceptions to the majority of the challenges were largely influenced (p < 0.05) by education, access to formal training, farm size, and age. Given all the limitations found, current findings point to the prospects of designing strategies that support knowledge flows and capacitating the farmers with skills to combat the challenges.

Conservation of indigenous cattle genetic resources in Southern Africa's smallholder areas: turning threats into opportunities - A review.

The current review focuses on characterization and conservation efforts vital for the development of breeding programmes for indigenous beef cattle genetic resources in Southern Africa. Indigenous African cattle breeds were identified and characterized using information from refereed journals, conference papers and research reports. Results of this current review reviewed that smallholder beef cattle production in Southern Africa is extensive and dominated by indigenous beef cattle strains adaptable to the local environment. The breeds include Nguni, Mashona, Tuli, Malawi Zebu, Bovino de Tete, Angoni, Landim, Barotse, Twsana and Ankole. These breeds have important functions ranging from provision of food and income to socio-economic, cultural and ecological roles. They also have adaptive traits ranging from drought tolerant, resistance to ticks and tick borne diseases, heat tolerance and resistance to trypanosomosis. Stakeholders in the conservation of beef cattle were also identified and they included farmers, national government, research institutes and universities as well as breeding companies and societies in Southern Africa. Research efforts made to evaluate threats and opportunities of indigenous beef cattle production systems, assess the contribution of indigenous cattle to household food security and income, genetically and phenotypically characterize and conserve indigenous breeds, and develop breeding programs for smallholder beef production are highlighted. Although smallholder beef cattle production in the smallholder farming systems contributes substantially to household food security and income, their productivity is hindered by several constraints that include high prevalence of diseases and parasites, limited feed availability and poor marketing. The majority of the African cattle populations remain largely uncharacterized although most of the indigenous cattle breeds have been identified.

Double Bond Position Plays an Important Role in Delta-9 Desaturation and Lipogenic Properties of Trans 18:1 Isomers in Mouse Adipocytes.

The objective of this research was to study the delta-9 desaturation of individual trans (t) fatty acids that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on lipogenic gene expression in adipocytes. It was hypothesized that delta-9 desaturation and lipogenic properties of t-18:1 isomers depend on the position of double bond. Differentiated 3T3-L1 adipocytes were treated with 200 µM of t6-18:1, t9-18:1, t11-18:1, t13-18:1 or t16-18:1, cis (c)-9 18:1 or bovine serum albumin (BSA) vehicle control for 48 h. Cells were then harvested for fatty acid and gene expression analyses using gas chromatography and quantitative PCR respectively. Among t-18:1 isomers, t13-18:1 and t11-8:1 had the greatest percent delta-9 desaturation (44 and 41 % respectively) followed by t16-18:1 and t6-18:1 (32 and 17 % respectively), while c9-18:1 and t9-18:1 did not undergo delta-9 desaturation. Trans9-18:1 up-regulated (P < 0.05) the expression of lipogenic genes including fatty acid synthase and stearoyl-CoA desaturase-1 (P < 0.05), whereas the expression of these genes were not affected with other t-18:1 isomers (P > 0.05). Consistent with gene expression results, t9-18:1 increased the de novo lipogenic index (16:0/18:2n-6) compared with control cells and increased delta-9 desaturation index (c9-16:1/18:0) compared to other t-18:1 isomers (P < 0.05). The current study provides further evidence that the predominant trans fatty acid in PHVO (t9-18:1) has isomer specific lipogenic properties.

Isolation of α-linolenic acid biohydrogenation products by combined silver ion solid phase extraction and semi-preparative high performance liquid chromatography.

Polyunsaturated fatty acids typically found in cattle feed include linoleic (LA) and α-linolenic acid (ALA). In the rumen, microbes metabolize these resulting in the formation of biohydrogenation products (BHP), which can be incorporated into meat and milk. Bioactivities of LA-BHP, including conjugated linoleic acid (cis (c) 9,trans (t) 11-18:2 and t10,c12-18:2) and trans fatty acid isomers (t9-, t10- and t11-18:1) have been investigated, but effects of several BHP unique to ALA have not been extensively studied, and most ALA-BHP are not commercially available. The objective of the present research was to develop methods to purify and collect ALA-BHP using silver ion (Ag(+)) chromatography in sufficient quantities to allow for convenient bioactivity testing in cell culture. Fatty acid methyl esters (FAME) were prepared from perirenal adipose tissue from a cow enriched with ALA-BHP by feeding flaxseed. These were applied to Ag(+)-solid phase extraction, and eluted with hexane with increasing quantities of acetone (1, 2, 10, 20%) or acetonitrile (2%) to pre-fractionate FAME based on degree of unsaturation and double bond configuration. Fractions were collected, concentrated and applied to semi-preparative Ag(+)-high performance liquid chromatography (HPLC) for the isolation and collection of purified isomers, which was accomplished using isocratic elutions with hexane containing differing amounts of acetonitrile (from 0.015 to 0.075%). Purified trans-18:1 isomers collected ranged in purity from 88 to 99%. Purity of the ALA-BHP dienes collected, including c9,t13-18:2, t11,c15-18:2 and t10,c15-18:2, exceeded 90%, while purification of other dienes may require the use of other complementary procedures (e.g. reverse phase HPLC).

Effects of diets supplemented with sunflower or flax seeds on quality and fatty acid profile of hamburgers made with perirenal or subcutaneous fat.

Steers were fed grass hay or red clover silage based diets containing flaxseed or sunflower seed as sources of 18:3n-3 and 18:2n-6 respectively. Hamburgers were made from triceps brachii and perirenal or subcutaneous fat. Perirenal-hamburgers contained more polyunsaturated fatty acids (PUFA), several PUFA biohydrogenation intermediates (BHI), and 18:0 (P<0.05). Oxidative stability was similar across hamburgers (P>0.05). Sensory differences were found due to hamburger fat source, but were < one panel unit. Within perirenal-hamburgers, feeding flaxseed increased 18:3n-3 and its BHI (P<0.05), and feeding sunflower seed increased 18:2n-6 and its BHI (P<0.05). Feeding flaxseed increased off-flavour intensity and oxidation in perirenal-hamburgers (P<0.05). Feeding oilseeds in forage based diets while using perirenal fat to make hamburgers provides opportunities to increase PUFA and BHI with potential to impact human health, but control measures need to be explored to limit oxidation and off-flavours when feeding flaxseed.

Individual trans 18:1 isomers are metabolised differently and have distinct effects on lipogenesis in 3T3-L1 adipocytes.

The objective of this research was to study the metabolism of individual trans fatty acids (FAs) that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on FA composition and lipogenic gene expression in adipocytes. Differentiated 3T3-L1 adipocytes were treated with 200 µM of either trans-9-18:1, trans-11-18:1, trans-13-18:1, cis-9-18:1 or BSA vehicle control for 120 h. Trans-9-18:1 increased total cell FA content (µmole/well) compared to other FA treatments, which was mainly related to the accumulation of trans-9-18:1 in the cells. Adipocytes were able to desaturate a significant proportion of absorbed trans-11-18:1 and trans-13-18:1 (~20 and 30% respectively) to cis-9,trans-11-18:2 and cis-9,trans-13-18:2, whereas trans-9-18:1 was mostly incorporated intact resulting in a greater lipophilic index (i.e. decreased mean FA fluidity) of adipocytes. Trans-9-18:1 up-regulated (P < 0.05) the expression of lipogenic genes including acetyl-CoA carboxylase (1.65 fold), FA synthase (1.45 fold), FA elongase-5 (1.52 fold) and stearoyl-CoA desaturase-1 (1.49 fold), compared to the control, whereas trans-11-18:1 and trans-13-18:1 did not affect the expression of these genes compared to control. Our results suggest that the metabolism and lipogenic properties of trans-11-18:1 and trans-13-18:1, typically the most abundant trans FA in beef from cattle fed forage-based diets, are similar and are different from those of trans-9-18:1, the predominant trans FA in PHVO.

Predicting fat quality from pigs fed reduced-oil corn dried distillers grains with solubles by near infrared reflectance spectroscopy: fatty acid composition and iodine value.

This study tested the ability of near infrared reflectance spectroscopy (NIRS) to estimate the fatty acid (FA) composition and iodine value (IV) of backfat from carcasses of pigs fed reduced-oil corn dried distillers grains with solubles. NIRS was suitable for screening purposes for the proportions of total saturated, monounsaturated, polyunsaturated, n-3 and n-6 FAs and some individual FAs such as C16:0, C18:1, C18:2n-6 and C18:3n-3 (R(2)=0.80-0.89; RMSECVs, root mean square errors of cross-validation=0.21-1.37% total FA) in both cold and warm intact backfat samples. This technology also met the requirements for a quick screening for the backfat IV in both cold and warm intact samples (R(2)=0.90 and 0.87; RMSECVs=1.66 and 1.80% total FA, respectively), which would help provide differential feed-back to pig producers and the feed industry and may provide the opportunity for breeding pigs for a desirable fat quality.

Inclusion of sunflower seed and wheat dried distillers' grains with solubles in a red clover silage-based diet enhances steers performance, meat quality and fatty acid profiles.

The current study compared beef production, quality and fatty acid (FA) profiles of yearling steers fed a control diet containing 70 : 30 red clover silage (RCS) : barley-based concentrate, a diet containing 11% sunflower seed (SS) substituted for barley, and diets containing SS with 15% or 30% wheat dried distillers' grain with solubles (DDGS). Additions of DDGS were balanced by reductions in RCS and SS to maintain crude fat levels in diets. A total of two pens of eight animals were fed per diet for an average period of 208 days. Relative to the control diet, feeding the SS diet increased (P<0.05) average daily gain, final live weight and proportions of total n-6 FA, non-conjugated 18:2 biohydrogenation products (i.e. atypical dienes) with the first double bond at carbon 8 or 9 from the carboxyl end, conjugated linoleic acid isomers with the first double bond from carbon 7 to 10 from the carboxyl end, t-18:1 isomers, and reduced (P<0.05) the proportions of total n-3 FA, conjugated linolenic acids, branched-chain FA, odd-chain FA and 16:0. Feeding DDGS-15 and DDGS-30 diets v. the SS diet further increased (P<0.05) average daily gains, final live weight, carcass weight, hot dressing percentage, fat thickness, rib-eye muscle area, and improved instrumental and sensory panel meat tenderness. However, in general feeding DGGS-15 or DDGS-30 diets did not change FA proportions relative to feeding the SS diet. Overall, adding SS to a RCS-based diet enhanced muscle proportions of 18:2n-6 biohydrogenation products, and further substitutions of DDGS in the diet improved beef production, and quality while maintaining proportions of potentially functional bioactive FA including vaccenic and rumenic acids.

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.

Types of oilseed and adipose tissue influence the composition and relationships of polyunsaturated fatty acid biohydrogenation products in steers fed a grass hay diet.

The current study evaluated the composition and relationships of polyunsaturated fatty acid biohydrogenation products (PUFA-BHP) from the perirenal (PRF) and subcutaneous fat (SCF) of yearling steers fed a 70 % grass hay diet with concentrates containing either sunflower-seed (SS) or flaxseed (FS). Analysis of variance indicated several groups or families of structurally related FA, and individual FA within these were affected by a number of novel oilseed by fat depot interactions (P < 0.05). Feeding diets containing SS increased the proportions of non-conjugated 18:2 BHP (i.e., atypical dienes, AD) and conjugated linoleic acids (CLA) with the first double bond from carbon 7 to 9, trans-18:1 isomers with double bonds from carbon 6 to 12, and these PUFA-BHP had greater proportions in SCF compared to PRF (P < 0.05). Enrichment of conjugated linolenic acids, AD and CLA isomers with the first double bond in position 11 or 12, and t-18:1 isomers with double bonds from carbon 13 to 16 were achieved by feeding diets containing FS, with PRF having greater proportions than SCF (P < 0.05). Principal component analysis visually confirmed interaction effects on these groups/families of FA, and further confirmed or suggested a number of relationships between PUFA-BHP. Feeding SS or FS in a grass hay diet and exploiting adipose tissue differences, therefore, present unique opportunities to differentially enrich a number of PUFA-BHP which seem to have positive health potential in humans (i.e., t11-18:1, c9,t11-18:2 and c9,t11,c15-18:3).

Flaxseed fed pork: n-3 fatty acid enrichment and contribution to dietary recommendations.

The potential to increase n-3 fatty acid (FA) intake via flaxseed fed pork is underestimated when restricted to pure longissimus muscle, whereas a combination of muscle and adipose tissue is typically consumed. Presently, the FA content of pigs fed 0%, 5% and 10% dietary flaxseed for 11 weeks was measured in loin, picnic and butt primals (lean muscle with epimysium (L), L plus seam fat (LS), and LS plus 5 mm backfat (LSS)). The n-3 FA content necessary for an enrichment claim in Canada (300 mg/100 g serving) was exceeded in L from all primals when feeding 5% flaxseed, being 4 fold that of controls (P<0.001), with further enrichment from inclusion of associated adipose tissues (P<0.001). Increasing flaxseed feeding levels in combination with adipose tissue inclusion amplified total long chain n-3 FA (P<0.05), particularly 20:5n-3 and 22:5n-3. Flaxseed-fed n-3 FA enriched pork can contribute substantially to daily long chain n-3 FA intakes, particularly for societies with typically low seafood consumption.

Effects of feeding flaxseed or sunflower-seed in high-forage diets on beef production, quality and fatty acid composition.

Yearling steers were fed 70:30 forage:concentrate diets for 205 d, with either grass hay (GH) or red clover silage (RC) as the forage source, and concentrates containing either sunflower-seed (SS) or flaxseed (FS), each providing 5.4% oil to diets. Feeding diets containing SS versus FS significantly improved growth and carcass attributes (P<0.05), significantly reduced meat off-flavor intensity (P<0.05), and significantly increased intramuscular proportions of vaccenic (t11-18:1), rumenic (c9,t11-CLA) and n-6 fatty acids (FA, P<0.05). Feeding diets containing FS versus SS produced significantly darker and redder meat with greater proportions of atypical dienes (P<0.05). A significant forage × oilseed type interaction (P<0.05) was found for n-3 FA, α-linolenic acid, and conjugated linolenic acid, with their greatest intramuscular proportions found when feeding the RC-FS diet. Feeding GH versus RC also significantly improved growth and carcass attributes, sensory tenderness (P<0.05) and significantly influenced intramuscular FA composition (P<0.05), but overall, forage effects on FA profiles were limited compared to effects of oilseed.

Influence of α-tocopherol supplementation on trans-18:1 and conjugated linoleic acid profiles in beef from steers fed a barley-based diet.

The current study was conducted to determine the effect of different α-tocopherol (vitamin E) inclusion levels on trans(t)-18:1 and conjugated linoleic acid (CLA) profiles in subcutaneous and intramuscular fat of steers fed a barley-based diet. Fifty-six feedlot steers were offered a barley-based finisher diet (73% steam rolled barley, 22% barley silage and 5% supplement as-fed basis) with four levels of supplementary dl-α-tocopheryl acetate (340, 690, 1040 or 1740 IU/steer per day) for 120 days. Adding vitamin E to the diet had little effect on the overall fatty acid composition of intramuscular fat. The proportion of individual and total t,t- and cis(c),t-CLA, n-3 fatty acids, total polyunsaturated fatty acids (PUFA), mono-unsaturated fatty acids and saturated fatty acids to PUFA ratio in subcutaneous fat were not influenced (P > 0.05) by dietary vitamin E supplementation. Increasing levels of vitamin E led to linear reductions in t6-/t7-/t8-18:1 and t10-18:1 (P < 0.05), and linear increase in t11-/t10-18:1 ratio (P < 0.05) in subcutaneous fat. The content of 20:3n-6 and total n-6 in subcutaneous fat decreased (P < 0.05) linearly with increasing amounts of vitamin E. The subcutaneous fat n-6:n-3 ratio showed a quadratic (P < 0.05) response to vitamin E. In conclusion, although vitamin E supplementation has some potential to reduce t10-18:1 formation and increase t11-/t10-18:1 ratio in subcutaneous fat of cattle fed barley-based diets, the changes in the present study were limited and may not have been sufficient to impact on human health.

The labile lipid fraction of meat: from perceived disease and waste to health and opportunity.

The fatty acid composition of beef and pork has been stigmatized due to their relationships with several diseases from cardiovascular disease to cancer. Meat lipids are, however, one of the few components of meat that can be modified in content and composition, and can present opportunities for value added production and health promotion. Until regulations and policies are in place to define requirements for fatty acid enrichment, however, the process remains relatively academic. Once practical goals are in place for fatty acid enrichment in meat, both theory and practice need to converge for successful production of fatty acid enriched meat. The present review covers aspects of policy in Canada, and requirements for research networks to respond to theoretical and practical challenges associated with production of fatty acid enriched meat. Finally, needs for education and marketing are outlined which must be in place to truly realize a transition of meat lipids from perceived disease and waste to health and opportunity.

Dietary influence on the m. longissimus dorsi fatty acid composition of lambs in relation to protein source.

Dietary lipid effect, as a consequence of protein supplement, on lamb m. longissimus dorsi fatty acid composition was investigated, with emphasis on biohydrogenation intermediates. Crossbred lambs (White Swedish Landrace × Texel) were fed a barley-based diet without (CON) or with protein supplements including peas (PEA), rapeseed cake (RC) or hempseed cake (HC). The HC diet resulted in the highest muscle 22:6n-3 proportion, with the RC diet being similar (P<0.05). Protein supplement did not affect the c9,t11 conjugated linoleic acid (CLA) proportion, however the HC diet increased some minor CLA isomers, including t10,c12 CLA (P<0.05). The t10-18:1 and total trans-18:1 were lowest for the RC diet (P<0.05), likely relating to rumen conditions and precursor availability. The saturated, monounsaturated and branched-chain fatty acids were largely unaffected by protein supplement. In conclusion, feeding the RC diet lowered the t10-18:1 and total trans-18:1 in meat, and modestly increased 22:6n-3 content. The direction of these changes would be beneficial, making the RC diet the preferred protein supplement; however the magnitude of the changes in the present experiment may not be sufficient to have an impact on human health.

Stress reactivity and its relationship to beef quality in Nguni steers supplemented with Acacia karroo leaves.

The objective of this study was to determine the levels of catecholamines and their relationship to beef quality in Nguni steers fed on Acacia karroo leaves. A total of 30 19-month-old steers were randomly assigned to A. karroo leaves (AK), sunflower cake (SF) and the control with no supplement (CN) diets. The AK and SF diets provided the steers with an additional 150 g of protein per day for 60 days. Catecholamine levels were determined from urine samples collected from each steer before and after slaughter. The Musculus longissimus thoracis et lumborum was sampled for selected meat quality measurements. Nguni steers on the CN diet had higher (P < 0.05) concentrations of post-mortem urinary norepinephrine and dopamine compared with those that received the AK and SF diets. Norepinephrine was negatively linearly related (P < 0.05) to the Warner-Bratzler shear force value of meat aged for 21 days and cooking loss of meat aged for 2 days (CL2) in steers that were given the SF diet. Meat pH and drip loss values were inversely related (P < 0.05) to epinephrine concentration in steers that received the AK diet. Dopamine concentration was negatively linearly related (P < 0.05) to water holding capacity and CL2 for steers on the CN diet. For steers on the CN diet, lightness (L*) values increased (P < 0.05) with increase in dopamine concentration. It was concluded that stress responsiveness and its relationship to certain beef quality attributes could be positively manipulated by supplementation with A. karroo leaves.

Meat quality of Nguni steers supplemented with Acacia karroo leaf-meal.

The objective of the study was to determine the meat quality of Nguni steers supplemented with Acacia karroo leaf-meal. Thirty 19-month old steers were randomly assigned to A. karroo leaf-meal (AK), sunflower cake (SF) and a control (CN) diets. Steers on the AK and SF diets were given an additional 150 g of protein per day for 60 days. The steers were slaughtered at 21 months and the m.longissimus thoracis et lumborum was sampled for meat quality measurements. Steers that received SF diet had lighter-coloured (L*) (P<0.05) meat than those on AK and CN diets. The highest redness (a*) (17.3+/-0.29) values were recorded in steers supplemented with AK compared to those that received SF and CN diets. Diet had no effect on pH, drip loss, water holding capacity, sarcomere length, muscle bundle areas, myofibrillar fragment length, Warner-Bratzler shear force and cholesterol values. Steers supplemented with AK (22.4+/-0.08%) and SF (22.5+/-0.08%) had higher (P<0.05) meat protein content than those on the CN (20.2+/-0.08%) diet. Highest muscle fibre area (3472.6+/-119.51 microm(2)), fat content (1.2+/-0.11%) and cooking loss (25.2+/-0.73%) of meat aged for 2 days were recorded in steers given the SF diet compared to those on the AK and CN diets. Supplementing Nguni cattle with A. karroo leaf-meal produced beef of comparable quality to natural pasture alone but with a fresher appearance and higher protein content.

Ovarian activity, conception and pregnancy patterns of cows in the semiarid communal rangelands in the Eastern Cape Province of South Africa.

A study was conducted to determine the seasonal trends in ovarian activity, conception and pregnancy status of cows on communal rangelands in the Eastern Cape Province of South Africa. Ovarian activity and pregnancy status of 200 cows were determined through trans-rectal palpation in June, and October 2007 and January 2008. Month of conception was obtained by subtracting the estimated age of the foetus from the month when pregnancy diagnosis was performed. Body weights and body condition scores (BCS) were collected every month between March 2007 and January 2008. Although cows in the perennial grasslands had higher (P<0.05) body weights and BCS than those in the annual grasslands, they had a significant weight and condition loss between March and October. More than 90% of the cows in the annual grasslands were cycling in January (P<0.05). Over 60% of the cows in the perennial grasslands conceived between December and March compared to 46% in the annual grasslands. About 40% of the cows were pregnant in June in the annual and perennial grasslands. There were more cycling and pregnant cows with a BSC of 3 in the perennial grasslands in June and October compared to annual grasslands (P<0.05). Odds ratio estimates of cows exhibiting ovarian activity and pregnancy in the communal areas were highest for BCS. It was concluded that most cows conceived and exhibited ovarian activity between November and March, especially in the perennial grasslands. Future research should focus on supplementary feeding using locally available feed resources to improve cow reproductive performance in the dry months, particularly in the annual grasslands.