Antimicrobial growth promoters approved in food-producing animals in South Africa induce shiga toxin-converting bacteriophages from Escherichia coli O157:H7.

In this study, four antimicrobial growth promoters, including virginiamycin, josamycin, flavophospholipol, poly 2-propenal 2-propenoic acid and ultraviolet light, were tested for their capacity to induce stx-bacteriophages in 47 Shiga toxin-producing E. coli O157:H7 isolates. Induced bacteriophages were characterized for shiga toxin subtypes and structural genes by PCR, DNA restriction fragment length polymorphisms (RFLP) and morphological features by electron microscopy. Bacteriophages were induced from 72.3% (34/47) of the STEC O157:H7 isolates tested. Bacteriophage induction rates per induction method were as follows: ultraviolet light, 53.2% (25/47); poly 2-propenal 2-propenoic acid, 42.6% (20/47); virginiamycin, 34.0% (16/47); josamycin, 34.0% (16/47); and flavophospholipol, 29.8% (14/47). A total of 98 bacteriophages were isolated, but only 59 were digestible by NdeI, revealing 40 RFLP profiles which could be subdivided in 12 phylogenetic subgroups. Among the 98 bacteriophages, stx2a, stx2c and stx2d were present in 85.7%, 94.9% and 36.7% of bacteriophages, respectively. The Q, P, CIII, N1, N2 and IS1203 genes were found in 96.9%, 82.7%, 69.4%, 40.8%, 60.2% and 73.5% of the samples, respectively. Electron microscopy revealed four main representative morphologies which included three bacteriophages which all had long tails but different head morphologies: long hexagonal head, oval/oblong head and oval/circular head, and one bacteriophage with an icosahedral/hexagonal head with a short thick contractile tail. This study demonstrated that virginiamycin, josamycin, flavophospholipol and poly 2-propenal 2-propenoic acid induce genetically and morphologically diverse free stx-converting bacteriophages from STEC O157:H7. The possibility that these antimicrobial growth promoters may induce bacteriophages in vivo in animals and human hosts is a public health concern. Policies aimed at minimizing or banning the use of antimicrobial growth promoters should be promoted and implemented in countries where these compounds are still in use in animal agriculture.

Nutrient intake, digestibility, and utilization in goats fed graded levels of hempseed cake finisher diets.

Globally, the price of soybean meal, the most common proteinaceous ingredient in livestock diets, has become highly expensive prompting a search for alternative ingredients. Hemp seed cake is a promising alternative but could be limited by its high neutral detergent fiber and ether extract contents which impede nutrient intake and digestibility. However, some ruminant species such as goats have superior ability to digest high fiber and ether extract diets. Thus, the current research evaluated nutrient intake and digestibility, rumen fermentation, and microbial protein synthesis of goats fed hempseed cake as a substitute for soybean meal in finisher diets. A total of 25 Kalahari Red castrates (27 ± 3 kg, 4-5 months old) were assigned to five dietary treatments (5 goats/ diet) in a completely randomized design. A maize-lucerne-based finishing diet was formulated with hempseed cake substituting soybean meal as the primary protein ingredient at 0, 25, 50, 75, or 100 g/kg dry matter. Ether extract intake exhibited a positive linear trend (P ≤ 0.05) while crude protein intake and microbial nitrogen supply exhibited a negative linear trend (P ≤ 0.05) with dietary inclusion of hempseed cake. However, feeding hempseed cake did not influence (P > 0.05) apparent nutrient digestibility, rumen fermentation parameters and nitrogen use efficiency. In conclusion, the substitution of soybean meal for hempseed cake decreased crude protein intake and microbial nitrogen supply in goat finisher diets without compromising nutrient digestibility and nitrogen use efficiency. The study recommends partial or full replacement of soybean meal with hempseed cake in goat finisher diets.

Bioavailability of bioactive phytochemicals in selected tissues and excreta from goats fed hempseed cake (Cannabis sativa L.) finisher diets.

Hempseeds are rich in bioactive phytochemicals, yet little is known about their bioavailability in tissues and excreta of animals fed hemp seed cake. The study evaluated the bioactive phytochemicals and their antioxidant activity in the blood, liver, meat, feces, and urine from goats fed finishing diets containing graded inclusions of hempseed cake (HSC). Twenty-five wether goats (26.8 ± 2.9 kg) of 4-5 months were randomly allocated to five experimental diets containing increasing levels of HSC (0, 25, 50, 75, 100 g/kg DM) substituted for soybean meal (SBM) as the main protein source. Goats were allowed for period of 21 days for adaptation, and blood, fecal, and urine samples were collected on the 28th day of the experiment. The liver and right longissimus thoracis et lumborum were respectively collected at 60 min and 24 h after slaughter. Linear increases (P ≤ 0.05) in blood, liver, and urine magnesium; fecal manganese; and fecal copper were observed with increasing HSC inclusion in the diet. Liver and fecal selenium exhibited a decreasing linear trend (P ≤ 0.05) with HSC increment in diets. Diet did not affect (P > 0.05) meat and urine mineral contents, except urine magnesium. The 2,2-diphenyl-1-picrylhydrazyl, and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) of the blood, liver, and meat linearly increased (P ≤ 0.05) with dietary inclusion of HSC. Blood and liver ferric reducing antioxidant power quadratically increased (P ≤ 0.05) with HSC inclusion reaching a maximum at 50 g/kg dry matter. Current results suggest that inclusion of HSC up to 100 g/kg substituting SBM in goat diets can improve bioavailability of bioactive phytochemicals in the blood, liver, and meat.

Health value and keeping quality of chevon from goats fed finisher diets containing hemp (Cannabis sativa L.) seed cake.

Wether goats (n = 7) were fed finishing diets containing either 0, 25, 50, 75 or 100 g/kg DM of hempseed cake (HSC) substituting soybean meal to evaluate chevon fatty acid, volatile and oxidative profiles. Feeding HSC diets linearly decreased (P < 0.05) chevon c9-16:1, 16:0, total saturated FA (SFA) and protein oxidation but linearly increased (P < 0.05) t9-18:1, t11-18:1, conjugated linoleic acids, n-3 polyunsaturated FA (PUFA), individual long-chain n-6 PUFA and antioxidant activity. On day 1 and 7 of retail display, diets containing 75 and 100 g/kg DM HSC had greater (P < 0.05) TBARS than the other diet × day interactions. Addition of HSC to the diet increased (P < 0.05) and preserved (P < 0.05) chevon contents of hexanal and methyl caprate throughout the retail display period. Overall, feeding HSC up to 100 g/kg DM enhances chevon profiles of healthful PUFA, desirable flavor volatiles and protein shelf-stability.

Meat production, quality, and oxidative shelf-life of Haemonchus-parasitised and non-parasitised lambs fed incremental levels of sericea lespedeza substituted for lucerne.

The study evaluated the effects of feeding incremental levels of sericea lespedeza (SL; 0, 62.5, 125, 187.5 and 250 g/kg diet) substituted for lucerne on meat production, quality, and oxidative shelf-life of feedlot lambs infected or non-infected with Haemonchus contortus. There were no diet × infection status, and diet × retail display period effects for all the tested parameters (P > 0.05). Relative to the other diets, the 250 g/kg SL diet decreased (P ≤ 0.05) lamb growth performance and carcass yield. The SL diets experienced less (P ≤ 0.05) meat lipid oxidation than the control diet. Worm infection reduced (P ≤ 0.05) carcass yield and income-over-feed-costs without affecting meat quality (P > 0.05). Feeding SL had no effects on meat physicochemical, fatty acid, colour, and protein shelf-life profiles (P > 0.05). Overall, substituting lucerne with SL up to 187.5 g/kg in lamb feedlot diets has no effects on meat production and quality but enhances lipid stability regardless of infection.

Comparison of Three Diagnostic Methods to Detect the Occurrence of Fasciola Species in Communally Grazed Cattle in the North West Province, South Africa.

Fasciolosis causes significant economic losses in commercial cattle herds in South Africa, but its prevalence is unknown in most communal areas. A cross-sectional study was conducted with the aim of determining the occurrence of bovine fasciolosis using three different diagnostic methods in Moretele Local Municipality in Bojanala District, North West Province. Faecal samples were collected from 277 cattle of different breeds, ages, sex and faecal condition scores and examined using the sedimentation technique, quantitative real-time polymerase chain reaction (qPCR) and faecal antigen enzyme-linked immunosorbent assay (coproELISA). All samples were negative for bovine fasciolosis using coproELISA. A total of 73 (26.4%) samples were positive using the qPCR, while 36 were positive using the sedimentation technique, with low faecal egg counts (1 to 20 eggs per gram). The qPCR detected the highest positivity (26.4%, 95% CI 21.3, 32.0) followed by the sedimentation test (13.0%; 95% CI 9.3, 17.5). Location, breed, sex, age and faecal consistency score were not associated with positive qPCR results (p > 0.05). There was also no significant agreement (kappa = −0.011, p = 0.843) between qPCR and the sedimentation technique for the detection of Fasciola spp. The qPCR appeared to be the most sensitive method for detection of Fasciola spp. Further studies are required on the characterisation of Fasciola spp. in communal cattle in South Africa.

Occurrence, Serotypes and Virulence Characteristics of Shiga-Toxin-Producing Escherichia coli Isolates from Goats on Communal Rangeland in South Africa.

Shiga-toxin-producing Escherichia coli is a foodborne pathogen commonly associated with human disease characterized by mild or bloody diarrhea hemorrhagic colitis and hemolytic uremic syndrome. This study investigated the occurrence of STEC in fecal samples of 289 goats in South Africa using microbiological culture and PCR. Furthermore, 628 goat STEC isolates were characterized by serotype (O:H) and major virulence factors by PCR. STEC was found in 80.2% (232/289) of goat fecal samples. Serotyping of 628 STEC isolates revealed 63 distinct serotypes including four of the major top seven STEC serogroups which were detected in 12.1% (35/289) of goats: O157:H7, 2.7% (8/289); O157:H8, 0.3%, (1/289); O157:H29, 0.3% (1/289); O103:H8, 7.6% (22/289); O103:H56, 0.3% (1/289); O26:H2, 0.3% (1/289); O111:H8, 0.3% (1/289) and 59 non-O157 STEC serotypes. Twenty-four of the sixty-three serotypes were previously associated with human disease. Virulence genes were distributed as follows: stx1, 60.6% (381/628); stx2, 72.7% (457/628); eaeA, 22.1% (139/628) and hlyA, 78.0% (490/628). Both stx1 and stx2 were found in 33.4% (210/628) of isolates. In conclusion, goats in South Africa are a reservoir and potential source of diverse STEC serotypes that are potentially virulent for humans. Further molecular characterization will be needed to fully assess the virulence potential of goat STEC isolates and their capacity to cause disease in humans.

Chevon production and quality of Kalahari Red goats fed increasing levels of hempseed cake substituted for soybean meal.

A 42-d study was conducted to evaluate the effects of replacing soybean meal with increasing levels of hempseed cake (HSC) in goat finishing diets on growth performance, carcass and chevon quality attributes. Thirty-five, 3-month-old Kalahari Red wethers (25 ± 1.5 kg initial body weight) were randomly allocated to one of five dietary treatments with seven animals per treatment. Wethers were fed maize-lucerne based finishing diets with inclusions of 0 (control), 25, 50, 75 and 100 g/kg DM of HSC replacing soybean meal as the main protein source. Diet had no effect (P > 0.05) on daily feed intake, average daily gain, final body weight and income-over-feed costs. Carcass and meat quality attributes were not influenced (P > 0.05) by HSC, except intramuscular fat, which increased linearly (P ≤ 0.05) with HSC inclusion levels. It was concluded that HSC could completely replace soybean meal in goat finishing diets without affecting chevon production and quality.

A rapid and simple single-step method for the purification of Toxoplasma gondii tachyzoites and bradyzoites.

This study describes a simple method for the large-scale isolation of pure Toxoplasma gondii tachyzoites and bradyzoites. T. gondii tachyzoites were obtained from infected human foreskin fibroblasts (HFFs) and peritoneal exudates of mice, while tissue cysts containing bradyzoites were collected from chronically infected mice. Harvested cells and brain tissues were incubated in Hanks balanced salt solution (HBSS), containing 0.25% trypsin and 0.5% taurodeoxycholic acid (TDC) for 5 min. Subsequent washes in phosphate buffered saline (PBS) were conducted, and the cell viability of the preparations was good, as determined by flow cytometry and ability to reinfect HFF cells and propagate in mice. The purification procedure allowed for a rapid preparation of pure T. gondii tachyzoites and bradyzoites in sufficient quantity that can be used for downstream procedures. The advantage of the new method is that it is convenient and inexpensive.

Bioavailability and Bioefficacy of Hemp By-Products in Ruminant Meat Production and Preservation: A Review.

Plant by-products obtained from agro-industrial processes require valorisation to demonstrate their potential for enhancing animal health, meat production, and shelf life extension. One example is the fast-growing hemp industry, which produces seeds, leaves, seed oil, and cake. Studies on the nutritional value of hempseed cake have shown it can be a valuable source of protein in ruminant diets. However, there is limited documentation on the bioavailability and bioefficacy of hemp phytochemicals for improving ruminant health, production, and extending meat shelf life. The current review provides an overview of existing information on nutrient and phytochemical composition of hemp by-products, their bioavailability, and bioefficacy, and explores current limitations and prospects regarding their valorisation.

Towards a genomics approach to tick (Acari: Ixodidae) control in cattle: a review.

Ticks and tick-borne disease (TBD) are major challenges to cattle production in the tropics and subtropics. Economic losses associated with ticks amount to billions of dollars annually. Although efforts to eradicate ticks and TBD using chemical control strategies have been implemented in many developing countries for decades, these acaricides are costly, and cattle susceptibility to ticks remains unchanged. Traditional breeding methods, where the farmer selected animals using records to improve the host genetic resistance to ticks (HGRT), are less than fully effective and time consuming. The HGRT has been reported in literature. To date, solutions to fight ticks and TBD are still unclear. Development of single-nucleotide polymorphism (SNP) technologies has created an opportunity to estimate breeding values of animals from DNA samples. The use of SNP technology for genomic selection allows information retrieval from the genotype even before the gene is expressed; thus potentially giving farmers the ability to make selection decisions on HGRT at an earlier age. This review discusses factors that affect HGRT, breeding selection, immunology, and genomic approaches and their application to improve HGRT in order to enhance livestock production.

Cellular responses to Rhipicephalus microplus infestations in pre-sensitised cattle with differing phenotypes of infestation.

The blue tick, Rhipicephalus microplus, threatens cattle production in most tropical and subtropical areas of the world. Delayed skin hypersensitivity reactions are thought to cause Nguni cattle to be more resistant to R. microplus than Bonsmara cattle yet the cellular mechanisms responsible for these differences have not been classified. Tick counts and inflammatory cell infiltrates in skin biopsies from feeding sites of adult R. microplus ticks were determined in 9-month-old Nguni and Bonsmara heifers to determine the cellular mechanisms responsible for tick immunity. Nguni heifers (1.7 ± 0.03) had lower (P < 0.05) tick counts than the Bonsmaras (2.0 ± 0.03). Parasitized sites in Nguni heifers had higher counts of basophils, mast and mononuclear cells than those in the Bonsmara heifers. Conversely, parasitized sites in Nguni heifers had lower neutrophil and eosinophil counts than those in the Bonsmara heifers. Tick count was negatively correlated with basophil and mast cell counts and positively correlated with eosinophil counts in both breeds. In the Bonsmara breed, tick count was positively correlated with mononuclear cell counts. Cellular responses to adult R. microplus infestations were different and correlated with differences in tick resistance in Nguni and Bonsmara cattle breeds. It is essential to further characterise the molecular composition of the inflammatory infiltrate elicited by adult R. microplus infestation to fully comprehend immunity to ticks in cattle.

Relationships between tick counts and coat characteristics in Nguni and Bonsmara cattle reared on semiarid rangelands in South Africa.

Indigenous Nguni cattle are adapted to the semiarid rangeland and appear to be resistant to ticks; however, the mechanism for tick resistance is yet to be established. To understand tick resistance in cattle, relationships among skin thickness, hair length, coat score, and tick counts were estimated in Nguni (n=12) and Bonsmara (n=12) heifers on semiarid rangelands of South Africa. The tick species observed to infest the heifers were Rhipicephalus (Boophilus) decoloratus (frequency: 76%), Rhipicephalus (Boophilus) microplus (9%), Amblyomma hebraeum (5%), Rhipicephalus appendiculatus (5%), Rhipicephalus evertsi evertsi (3%), and Hyalomma marginatum (2%). Nguni heifers had lower (P<0.05) log(10) (x+1)-transformed coat scores (0.6±0.01), hair length (1.4±0.01), and tick counts (1.4±0.03) than Bonsmara heifers whose log(10) (x+1)-transformed coat score, hair length, and tick count values were 0.7±0.01, 1.5±0.01, and 1.8±0.02, respectively. The skin thickness between the two breeds were similar (P>0.05). There was a positive linear (P<0.05) relationship between log(10) (x+1) tick counts and log(10) (x+1) coat score in the Nguni (y=1.90x-0.40) and a quadratic relationship in the Bonsmara (y=-7.98x(2)+12.74x-3.12) breed. It was concluded that the smooth coats may be one of the important mechanisms of tick resistance in the indigenous Nguni breed. Determination of genetic resistance to ticks in the Nguni breed is recommended as this will give more specific indication to the mechanism of host resistance in this breed.

Tick loads in cattle raised on sweet and sour rangelands in the low-input farming areas of South Africa.

The objective of this study was to compare tick loads and prevalence in Nguni and non-descript cattle in the sweet (palatable throughout the year) and sour (palatable only in the rainy season) communal rangelands of the Eastern Cape Province, South Africa. Engorged adult female ixodid ticks were collected and identified seasonally from 144 cattle raised on sweet and sour rangelands from August 2007 to April 2008. Three tick species were identified in the sweet and sour rangelands namely Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) decoloratus, and Rhipicephalus evertsi evertsi with prevalences of 71.1%, 29.2%, and 40.2%, respectively. Hyalomma species (19.0%) occurred only in the sour rangeland. Higher tick counts were recorded in the hot-wet season than in the cool-dry season (P < 0.05). Cattle in the sweet rangeland had significantly lower tick loads than those in the sour rangeland in all the seasons except the hot-dry season. The Nguni breed had lower (P < 0.05) tick loads of R. appendiculatus in the hot-wet and post-rainy season and Hyalomma species in all seasons than the non-descript cattle. The use of a tick-resistant Nguni breed in the integrated control of ticks on cattle in the communal areas of South Africa is recommended.

Seroprevalence of tick-borne diseases in communal cattle reared on sweet and sour rangelands in a semi-arid area of South Africa.

A survey was conducted to determine the seroprevalence of tick-borne diseases (TBD) in Nguni and non-descript cattle on the sweet and sour communal rangelands across seasons. Body condition scores, bodyweights, packed cell volume (PCV) and antibodies to B. bovis, B. bigemina, Ehrlichiaruminatium and Anaplasma marginale were determined seasonally in 144 cattle raised on communal rangelands from August 2007 to April 2008. Approximately 45% of the cattle were seropositive for B. bovis, 46% for B. bigemina and 26% for A. marginale. All animals were seronegative for E. ruminantium. Nguni cattle had lower (P<0.05) seroprevalence for A. marginale and B. bigemina in the cool-dry and hot-wet seasons. Cattle in the sweet rangeland had significantly lower seroprevalence of B. bovis and B. bigemina in all the seasons. Infection with B. bovis and B. bigemina negatively affected (P<0.05) bodyweight and body condition scores whilst B. bovis and A. marginale infections significantly affected PCV. The seroprevalence of TBD was lower in the Nguni breed. More work is required to understand the mechanisms of the adaptation and possible resistance of Nguni cattle to TBD.