Profitable Livestock Production Research Articles

Prevalence of gastrointestinal parasites of pigs in Abakaliki, Ebonyi State, South-Eastern Nigeria

Gastrointestinal parasites are responsible for substantial loss of productivity in swine and other livestock industries, they constitute a major impediment to efficient and profitable livestock production. The objective of the study is to determine the prevalence and evaluate the risks factors associated with gastrointestinal parasites among pigs in the study area. Methodologically, faecal samples were macroscopically examined for the presence of blood and adult parasites. Direct smear method, floatation technique and sedimentation by centrifugation were employed to detect the presence of eggs of parasites. Results identified eight intestinal parasites from a total of 300 fecal samples in pigs from different farms in Abakaliki metropolis, with an overall prevalence of 99.7%. Ascaris suum had the highest prevalence of 30.6%, followed by Metastrongylus spp. 17.5%, Cryptosporidium spp. 17.1%, Trichuris suis 10.6%, Eimeria spp. 10.2%, Oesophagostomum spp. 6.12%, Isospora suis 4.0% and Paragonimus westermanii 3.6%. In the present study, it can be deduced that gastrointestinal parasitism can occur in any farm irrespective of the type of housing, and management practices. Therefore, improved husbandry system and modern management practices should be embraced to enhance preventive measures against helminthosis.

Barn and Environmental Characteristics of Cattle Enterprises in Central County of Ağrı Province

In this study, a survey was conducted with 400 enterprise owners in order to determine the current situation and problems related to the structural characteristics of the barns in cattle enterprises located in the central county of Ağrı province, and the data obtained were transferred into Microsoft Excel program and frequency analysis was performed in SPSS statistical program. Findings were evaluated through graphs obtained from proportional values. It was determined that 66% of the enterprises have free-stall closed barns, the barns in 48.5% of the enterprises were used for less than 10 years and the barns were generally detached (98.5%). Building material for the walls of the barns was mostly stone (72.8%), and sheet metal (72.8%) was the most preferred material for the construction of the roof, and the floors of the were generally made of concrete (88.8%). The feed alley (15%) and automatic waterers (2.8%) are available in a small percentage of the barns. It was determined that 88% of the cattle farms have individual calf units, and calves in the most of the enterprises are housed in a separate group sections (87.5%) in the same barn. Only 15% of the enterprises used bedding and 85% of them did not have bedding material. The majority of the enterprises watered the animals with buckets (51.5%) and village's fountain or trough (43.8%). It also found out that 62.3% of the enterprises implemented general cleaning and 99.3% cleaned the manure with manpower. Furthermore, 94.5% of the enterprises stored the manure near the barn without any cover. In addition, 72.5% of the cattle farms utilized from the manure for heating purpose and 51% of them used it as fertilizer in their field. As a result of the findings, it was concluded that the information support and investment incentives to be given to the enterprises and the training of breeders could be helpful to ensure profitable livestock production in the region.In this study, a survey was conducted with 400 enterprise owners to determine the current situation and problems related to the structural characteristics of the barns in cattle enterprises located in the central county of Ağrı province. The data obtained were transferred into Microsoft Excel program. Frequency analysis was performed in SPSS statistical program. Findings were evaluated through graphs obtained from proportional values. It was determined that 66% of the enterprises had free-stall closed barns, the barns in 48.5% of the enterprises were used for less than 10 years and the barns were generally detached (98.5%). The building material for the walls of the barns was mostly stone (72.8%), and sheet metal (72.8%) was the most preferred material for the construction of the roof, and the floors were generally made of concrete (88.8%). The feed alley (15%) and automatic waterers (2.8%) are available in a small percentage of the barns. It was determined that 88% of the cattle farms have individual calf units, and calves in most enterprises are housed in separate group sections (87.5%) in the same barn. Only 15% of the enterprises used bedding and 85% did not have bedding material. The majority of the enterprises watered the animals with buckets (51.5%) and the village’s fountain or trough (43.8%). It also found out that 62.3% of the enterprises implemented general cleaning and 99.3% cleaned the manure with human resources. Furthermore, 94.5% of the enterprises stored the manure near the barn without any cover. In addition, 72.5% of the cattle farms utilized manure for heating purposes, and 51% used it as fertilizer in their field. As a result of the findings, it was concluded that the information support and investment incentives to be given to the enterprises and the training of breeders could be helpful to ensure profitable livestock production in the region.

Molecular detection and genetic characterization of Anaplasma marginale and Anaplasma platys in cattle in Nigeria

Bovine anaplasmosis poses serious challenge to profitable livestock production in the tropics. Accurate information on the prevalence, distribution and genetic characteristics of Anaplasma spp. infections of cattle is invaluable for the design of cost-effective control measures. Blood samples from 275 cattle in Nigeria were screened for the DNA of Anaplasma spp. using species-specific primers and nucleotide sequence analysis. The DNA of Anaplasmataceae was detected based on 16S rRNA gene in 135 out of the 275 (49.1%) individuals examined, with 31 (23.0%) and 21(15.6%) being positive for Anaplasma marginale based on msp4 and msp2 genes, respectively. DNA of Anaplasma platys was detected in 62 (45.9%) based on groEL gene and in 27 (20.0%) using the A. platys species-specific primers. Presence of Anaplasma spp. DNA was significantly associated (p = 0.011) with the breed of the animals. Anaplasma nucleotide sequences of one group of the infected samples showed high identities of 99.0 to 100% (16S rRNA gene) and 99.6% (groEL gene) with reference sequences of A. platys, while those of another group matched to A. marginale references (msp2 with 98.9% and msp4 with 99.1%). Furthermore, phylogenetic analysis clustered the nucleotide sequences in this study with A. platys and A. marginale sequences in GenBank, confirming these relationships. For the first time, this study revealed the presence of mixed haplotypes in both A. platys and A. marginale in cattle in Nigeria. More studies are needed to elucidate the epidemiology and veterinary and public health significance of Anaplasma spp. infections in cattle in Nigeria.

Livestock Production Challenges and Improved Forage Production Efforts in the Damot Gale District of Wolaita Zone, Ethiopia

This study was conducted to identify major livestock production constraints and improved forage production efforts in the Damot Gale district. Four representative kebeles, two associated with our NGO project and two from nonproject outreach activities, were selected. Forty farmers from each kebele were randomly chosen for the purpose of individual interviews using a semistructured questionnaire. Data collected were analyzed using SPSS (version 20) and Excel. The topmost livestock production constraint was feed shortage where a larger proportion of farmers (75.6%) suffered from the problem with higher ( p ≤ 0.01) severity in nonproject intervention areas. Of these, 38.6% were challenged for a period of three months while another 61.4% suffered for about four months. Purchasing grass (31.4%) and concentrate (33.5%) and feeding enset (Ensete ventricosum) leaf (21.49%) were the most commonly adopted coping mechanisms to alleviate feed shortages during the dry season, while using purchased grass and enset leaf was the main coping strategy in nonproject intervention ( p ≤ 0.01) areas. The majority of households (90.75%) participate in improved forage production regardless of farm size. Desho grass (Pennisetum pedicellatum) (71.38%) and elephant grass (Pennisetum purpureum) (42.63%) are the most common improved forages in both study areas. These forages are produced for the purpose of two or more functions (feed, cash, and preventing erosion) that vary ( p ≤ 0.01) among intervention status. Major niche locations adopted for improved forage production include farm land, soil and water conservation structures, and perimeter fencing. Greatest constraints on improved forage production were seed/material shortage followed by land shortage and lack of awareness. Project intervention ( p ≤ 0.01), tropical livestock unit (TLU) holding ( p ≤ 0.01), and forage seed/planting material access ( p < 0.05) were identified as factors (among others) having significant relationship with improved forage development. Strong extension services and efficient input delivery for farmers are vital to support profitable livestock production and resource utilization.

Bioactivity and cytotoxicity profiling of vincosamide and strictosamide, anthelmintic epimers from Sarcocephalus latifolius (Smith) Bruce leaf

Ethnopharmacological relevanceThe leaf of Sarcocephalus latifolius is known to be used traditionally by the Fulanis in Nigeria to deworm animals. As helminthosis remains a major constraint to profitable livestock production worldwide, a precarious situation aggravated by the advent of resistant parasites, the discovery of new anthelmintics is a priority, necessitating exploration of medicinal plants for their anthelmintic principles. Aim of the studyTo identify and characterise compounds with anthelmintic activity from the leaf of Sarcocephalus latifolius. Materials and methodsPowdered S. latifolius leaves were extracted by successive maceration with n-hexane, chloroform and acetone. The dried extracts were evaluated for anthelmintic activity against Haemonchus placei adult worms, and the most active extract was subjected to bioassay-guided chromatographic separations. The isolated compounds were evaluated for cytotoxicity against the mammalian HeLa and MC3T3-E1 cell lines, using alamar blue and CellTitreGloTM to quantify cell viability. LC50 values were computed from the in vitro anthelmintic activity data by fitting to a non-linear regression equation (variable slope). Isolated compounds were characterized using spectroscopic and mass spectrometric analyses. ResultsAnthelmintic activity LC50 values for n-hexane, chloroform and acetone extracts were 47.85, 35.76 and 5.72 (mg/mL), respectively. Chromatographic separation of acetone extract afforded two bioactive epimers, identified as vincosamide (LC50 14.7 mg/mL) and strictosamide (LC50 12.8 mg/mL). Cytotoxicity evaluation showed that, below 200 μg/mL (400 μM), neither compound was toxic to the HeLa or MC3T3-E1 cells. ConclusionVincosamide and strictosamide could serve as novel scaffolds for the development of anthelmintic derivatives with improved potency and helminth selectivity.

Prevalence and Factors Affecting the Parasitic Infections in Calves at Selected Areas of Bangladesh

Gastrointestinal parasitic infections are considered as one of the major impediments in profitable livestock farming in subtropical and tropical countries. The present study was carried out to investigate the prevalence of gastrointestinal (GI) parasites and to determine the effects of different factors in the occurrences of GI parasitic infections in calves. A cross-sectional study, including 413 fecal samples from calves, was conducted in Pabna, Sirajgonj and Gazipur districts of Bangladesh. The samples were examined using standard coprological techniques like sedimentation and floatation techniques, and lugol’s iodine and modified Ziehl-Neelson staining. The overall prevalence of gastrointestinal parasitism was 45.3% and commonly identified parasites were Toxocara spp. (20.3%), Strongyloides spp. (3.9%), Fasciola sp. (1.0%), Moniezia spp. (1.5%), Giardia sp. (10.4%) and Cryptosporidium spp. (7.0%). Among the factors, the age, sex and health status had significant effects on the GI parasitic infections in calves. Therefore, special care such as routine fecal examination for parasitism and proper deworming program should be taken to maintain good health and husbandry of calves for profitable livestock production.
 Ann. Bangladesh Agric. (2019) 23(2) : 1-13

Application of reproductive biotechnologies for sustainable production of livestock in Turkey

Reproductive biotechnology encompasses powerful tools to enhance the efficiency and profitability of livestock reproduction, production, and product quality. These technologies include genomic selection, evaluation of semen (from bulls, bucks, and rams) using advanced cell and molecular technologies, semen cryopreservation and artificial insemination, estrus synchronization, superovulation of the females (cows, dams, and ewes), ovum pick-up, in vitro fertilization and embryo culture, embryo transfer, and pregnancy detection. The extent of applications of these modern technologies and their economic impacts for livestock production in Turkey are elusive. As a result, there is an urgent need for sound economic analyses, research and education, training of animal producers to facilitate technology transfer, and informing of the public of the benefits of animal biotechnology. The objective of this study was to provide a review of key reproductive technologies and economic analyses of them, followed by an outlook on the future production of cattle, goats, and sheep in Turkey. This review is an important resource for students, researchers, and producers for a better understanding and for the application of cutting-edge biotechnology in efficient, sustainable, and profitable livestock production.

Assessment Study on Livestock Feed Resource, Feed Availability and Production Constraints in Maale Woreda in South Omo Zone

The study was carried out in Maale Woreda, in South Western Ethiopia aimed to assess feed resource, feed resource availability and feed production constraints. Six Kebeles per Woreda were selected and one focus group discussion which comprised 12 pastoralists per kebele were identified and interviewed. For the key informants’ interview, two livestock production experts from Woreda Livestock and Fisher Resource development Office and six livestock developmental agents from representative kebeles were interviewed. The focus group discussion and key informants interview was used to collect primary data on feed resource, feed resource availability, feed conservation practices and feed resources utilization and major livestock feed constraints. The study results shown that grass from the open grazing land, indigenous browse species and crop residues were major feed resources for the livestock in to study area. The open grazing land had poorly managed and the biomass productivity generated from open grazing land has been retreated. The major livestock feeding system was free grazing and Agro pastoral communities had no trends of conserved feed and provided concentrate supplements to the livestock. There were lack of low quality feed improvement and trends of growing the cultivated fodder species production practices. The 83,783.60 tons of dry matter was produced from different feed resources in the Maale Woreda with deficit of 623,333.40 tons of dry matter per year. The climate change, expansion of cropping land, increments in human populations, lack of inputs and training were identified as livestock feed production constraints in to study area. The migration, supplementations and purchasing available feed were important coping strategies toward feed shortage in to study area. Generally, the results from this study demonstrated that the total dry matter produced from different feed resources in to the study area was not enough to satisfy the dry matter requirement of livestock to support the profitable livestock production in to the study area, which suggest that the primary focus needs to be improving the existing feed resources through rehabilitation of degraded grazing areas, introduction adaptable fodder production, improving feed utilization practices and introduce and promote the crop residue feed improvement technologies.

Seasonal variation in prevalence of gastrointestinal helminthoses in cattle of New Alluvial zone of West Bengal, India

Gastrointestinal parasitism is one of the major constraints for profitable livestock production. The present study was conducted to determine the prevalence and seasonal variation in gastrointestinal helminthic infections in cattle of New Alluvial zone of West Bengal. A total 2520 faecal samples of cattle were collected from five different places of NAZ of West Bengal during the study period i.e. March 2014 to February 2015. The faecal samples were examined by standard sedimentation and floatation technique. The overall prevalence of gastrointestinal parasites was recorded as 55.71% in cattle of NAZ and Paramphistome (40.64%) was recorded as the predominant parasite followed by Strongyle group of nematodes (8.25%) and Fasciola (3.33%). Moniezia was the only cestode parasite recorded with an overall prevalence of 1.97%. Statistically significant (p < 0.05) variation was observed in the prevalence of gastrointestinal helminths among the various seasons. Monsoon season has significantly (p < 0.05) higher prevalence of gastrointestinal helminthes (64.28%) followed by winter (57.14%) and lowest in summer (45.24%). Prevalence of Paramphistome (47.62%) and Strongyle (9.52) were also significantly (p < 0.05) higher monsoon compared to other seasons. The epidemiological knowledge/information gathered in the present study would be exploited for evolving strategic control method against gastrointestinal parasitic infections in cattle.

Genetic diversity among Trypanosoma vivax strains detected in naturally infected cattle in Nigeria based on ITS1 of rDNA and diagnostic antigen gene sequences.

Trypanosoma vivax (sub-genus Duttonella) is largely responsible for non profitable livestock production in sub-Sahara Africa. In Nigeria, no study has addressed the molecular characteristic of T. vivax except Y486. Hence, we characterized and assessed the genetic diversity among T. vivax detected in naturally infected cattle in Nigeria using internal transcribed spacer 1 (ITS1) of ribosoma DNA (rDNA) and diagnostic antigen gene (DAG) sequences. The length of ITS1 and DAG sequences range from 215-220 to 257-338bp, respectively and the mean G-C contents were 60 and 61.5%. Homology search revealed 93-99 and 95-100% homologies to T. vivax DAG and ITS1 sequences from GenBank. Aligned sequences revealed both ITS1 rDNA and DAG to be less polymorphic but DAG sequences of the Y486 strain and its clone showed marked variation from autochthonous strains. Phylogenetic analysis yielded tree that grouped T. vivax ITS1rDNA gene and DAG sequences into two main clades each. Considering the ITI1 rDNA sequences, clade A contained autochthonous T. vivax within which the South American sequences clustered, clade B contained the sequences of T. vivax from East Africa. Analysis of DAG revealed that the clade A contains autochthonous T. vivax sequences but clade B contained the Y486 and its clones. In conclusion, the diagnostic antigen gene sequences of the T. vivax detected in this study may have undergone considerable gene recombination through time and suggests that more than one strain of T. vivax exist among cattle population in Nigeria.

Differential IFN-Gamma (IFN-&amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt;), Interleukin 10 (IL-10) and Cardiac Troponin I (cTnI) Responses in Natural Bovine Trypanosomosis in Nigeria

Trypanosomosis is major drawback to profitable livestock production in sub-Sahara African, including Nigeria. Knowledge of the cytokines production in the phase of natural infection may help to better diagnose, treat and prevent bovine trypanosomosis. The purpose of the this study was to determine the levels of interferon-gamma (IFN-γ), interleukin-10 (IL-10) and cardiac troponin–I (cTnI) in the sera of cattle naturally infected with T. brucei, T. congolense and T. vivax and correlate these levels with parasitaemia and PCV of the infected animals. Five milliliter of blood samples were collected via the jugular vein from 411 randomly selected cattle into EDTA and non-citrated bottle. PCV was determined manually using HCT. Trypansomes were detected and characterized by microscopy and PCR, respectively. Serum levels of IFN-γ, IL-10 and cTnI were determined using commercial ELISA kit. Data were summarized using descriptive statistic and significance of differences determined by ANOVA. Of the 62 samples positive for trypanosomes by microscopy, 50 samples were confirmed to species level by PCR. The sera levels of IFN-γ, IL-10 and cTnI of infected cattle were higher than non-infected cattle. The differences were not significant (p γ, IL-10 and cTnI in cattle with natural trypanosomosis. Further investigation is required to understand the specific effect of trypanosomes on myocardiac integrity and interaction between the two cytokines in natural trypanosomosis in cattle.

Effect of concentrate supplementation on herbage intake and live weight gain of sheep grazing a semi-arid grassland steppe of North-Eastern Asia in response to different grazing management systems and intensities

An increasing human population and growing demand for food of animal origin intensified livestock production and lead to overgrazing and desertification in semi-arid grasslands. Strategies for sustainable livestock production that protect steppe vegetation and satisfy farmers׳ economic interests are strongly needed. This study analysed the effects of a moderate concentrate supplementation on organic matter digestibility (dOM), organic matter intake (OMI), metabolisable energy intake (MEI), and live weight (LW) gain of sheep grazing at different intensities to evaluate its potential contribution to profitable livestock production at conservative stocking densities (SD). In 2010, a grazing experiment was conducted in the Xilin River Basin, the Inner Mongolian steppe, China (E116°42′ N43°38′) using 337 female Mongolian fat-tailed sheep (30.2±4.3kg LW). The effect of concentrate supplementation was tested in two different grazing management systems and six classes of herbage allowances (HA). While experimental plots had only been used for grazing in previous years in the continuous system, grazing and hay-making had been alternated annually on plots of the alternating system. The SD ranged from light to heavily grazed with 2.1–10.3 sheep/ha and were adjusted every month to maintain similar HA across the grazing season. Four sheep per plot received 250g/d of a corn–wheat-based concentrate feed (SUP), while four non-supplemented (NSUP) sheep were used as control. Faecal samples were collected on five days each in July, August, and September. The dOM was estimated from faecal crude protein concentration and faeces excretion quantified using the marker titanium dioxide. The animals were weighed monthly to determine daily LW gain. The dOM was higher in SUP than NSUP sheep (0.557 vs. 0.533, RSD: 0.016). As a consequence, daily OMI and LW gain of SUP sheep (74g/kg0.75 LW; 121g) were higher than of NSUP sheep (68g/kg0.75 LW, RSD: 6.4; 86g, RSD: 24.6) despite a decrease in herbage OMI of 0.41g per 1g concentrate feed. Grazing system had no influence on dOM, OMI, or LW gain of sheep. The effects of supplementation were independent of HA class, and OMI, herbage OMI, MEI, and LW gain were higher in the beginning than in the end of the experiment. Moderate concentrate supplementation to grazing sheep strongly increases LW gain of individual animals and might offer a valuable contribution to increase individual productivity, maintaining the output per area at lower SD. A reduced herbage OMI alleviates grazing pressure and can thus maintain long-term grassland productivity.

FIELD EVALUATION OF Lablab Purpureus (L.) SWEET ACCESSIONS FOR DROUGHT TOLERANCE IN THE NIGERIAN MOIST SAVANNA

Profitable livestock production during dry season in the moist savanna of Nigeria is limited by lack of adequate feed. However, introduced forage legumes that are drought tolerant have the potential to contribute to increased livestock productivity. Lablab purpureus (L.) Sweet commonly called lablab has been identified as a promising forage legume in the zone. 46 accessions were screened for drought tolerance. Four accessions (ILRI 730, NAPRI 3, PI 195851 and PI 388013) were selected as best choices in drought tolerance throughout the dry season (November-April). Seven others (BARSD 1, GRIF 1246, ILRI 4612, ILRI 6930, ILRI 7403, NAPRI 2 and NAPRI 4) were identified as drought tolerant up to mid dry season (January-February). Identified accessions either flowered late and had large biomass yields or had delayed leaf senescence (DLS)

Growth of sheep as affected by grazing system and grazing intensity in the steppe of Inner Mongolia, China

The Inner Mongolian grassland steppe is the most important grazing land in China in terms of cow milk, mutton, and cashmere production. However, intensive livestock grazing has severely degraded the steppe grassland. A sophisticated grazing management is therefore essential for an economically viable use of the grassland without amplifying its desertification. The objective of this study was to evaluate the effects of different grazing management systems and grazing intensities (GI) on liveweight gain (LWG) of sheep grazing the Inner Mongolian steppe in order to derive recommendations for a sustainable grassland use which considers both, farmers' interests of a profitable livestock production as well as environmental goals. A 5-year grazing experiment was conducted in June–September of 2005–2009 in which six different GI's (≥12, 6–12, 4.5–6, 3–4.5, 1.5–3, and ≤1.5kg herbage dry mass kg−1 liveweight) and two different grazing systems were installed. The two systems included an alternating grazing system where grazing and hay-making alternated annually between two plots, and a continuous grazing system where the same plots were used either for hay-making or for grazing each year. Grazing system had no or only minor effects on sheep's LWG. However, LWG per sheep linearly decreased with increasing stocking rate, resulting in diminishing responses in LWG per ha. LWG per sheep and per ha were lowest in a dry year and decreased with advancing vegetation period. In view of our earlier published data on the effect of GI on the steppe vegetation, we conclude that grazing at GI's which allows for an end-of-season biomass that is sufficient to prevent grassland degradation does not lead to large deprivations in liveweight yield. Complementary management strategies such as supplement feeding of grazing animals may compensate for this deprivations as well as for inter- and intra-annual variations in herbage growth and quality. They can thus further contribute to a sustainable use of Inner Mongolian steppe.

On-farm evaluation of the effect of coffee pulp supplementation on milk yield and dry matter intake of dairy cows grazing tropical grasses in central Mexico

Tropical grasses are the primary nutrient resource for cattle production in the tropics, and they provide low-cost nutrients to cattle. However, its production is constrained by seasonal changes and quality; hence, appropriate usage of relatively inexpensive agricultural by-products is important to profitable livestock production. The objective of the study was to evaluate the effect of supplementing coffee pulp to dairy cows grazing tropical grasses on milk yield and forage intake. Four multiparous crossed Holstein-Brown Swiss-Zebu cows of similar weight and milk yield were used. The effect of 10%, 15% and 20% inclusion of coffee pulp in dairy concentrates on milk yield and forage intake was analysed using a 4 × 4 Latin square design. Results showed that there were no significant effects (P > 0.05) in grass dry matter intake, milk yield, milk composition body weight and body condition score due to the inclusion of coffee pulp in the dairy concentrates. It is concluded that coffee pulp can be included at levels of 20% in the concentrate without compromising significantly (P > 0.05) milk yield, milk composition and grass dry matter intake. It also was concluded that cost of concentrate is reduced in 20% by the inclusion of coffee pulp.

Plasma pharmacokinetics of oral chlortetracycline in group fed, ruminating, Holstein steers in a feedlot setting

Chlortetracycline HCl (CTC) has impacted profitable livestock production since 1945. However, pharmacokinetic parameters for CTC in ruminating cattle are unavailable in peer-reviewed literature. A total of 18 steers were randomized to 4.4, 11, or 22 mg/kg/day p.o. CTC treatment groups (n = 6). Chlortetracycline treatment was offered as one-half of the daily dose b.i.d. (160 total doses/group) for 80 days. Blood samples were collected at selected time points throughout an 83-day study and analyzed with a solid phase extraction technique and novel ultrahigh performance liquid chromatography-mass spectroscopy/mass spectroscopy analytical method. Noncompartmental analysis (NCA) determined individual pharmacokinetic parameters by treatment group with coefficient of variation (CV %) estimates. A one-compartment open model with first order absorption and elimination, where absorption rate constant was equal to elimination rate constant, was fitted using nonlinear mixed effects modeling (NLMEM). NLMEM determined the primary pharmacokinetic parameters: volume of distribution (V/F, 40.9 L/kg) and rate constant (k, 0.0478 h(-1)), and the secondary parameters: dose-normalized area under the curve (AUC/D, 0.29 h x microg/L), clearance (Cl/F, 1.8 L/kg/h), elimination half-life (t(1/2), 16.2 h), C(max/Dose) (4.5 ng/mL), and time of C(max) (T(max), 23.3 h) with improved CV estimates over NCA. Dose linearity was confirmed by anova of parameters derived from NCA by treatment group. Further studies are necessary for determining absolute bioavailability and pharmacokinetic-pharmacodynamic relationships of CTC in group fed, ruminating cattle.

Plant influences on endophyte expression

Neotyphodium endophytes in the pooid grasses perennial ryegrass and tall fescue (Lolium spp.) are important ecologically and agriculturally by virtue of their ability to produce several alkaloids and their effects on host growth and responses to biotic and abiotic stresses. Such responses can be positive, neutral, or negative, and depend on the interaction of host genetics x endophyte genetics x environment (and management), which is complex and difficult to predict. Understanding the interactions is key to elucidating the ecological role of endophytes in natural and impacted ecosystems and to optimally select plant and endophyte combinations that support profitable livestock production with stable plant populations. High phenotypic variability among individual plants in an endophyte-infected population can promote population fitness across a wide range of stressful environments. Strong interactions between environmental conditions and host-endophyte combination reveal the importance of testing new grass-endophyte associations in the range of environments targeted for eventual use to determine stability of the desired traits. Care must also be taken when creating new symbiota that an important fitness trait is not lost by selecting endophytes that lack a particular alkaloid. Genetic variations within perennial ryegrass and tall fescue provide opportunities for plant breeders to perform further selections with novel symbiota to exploit host control over growth and physiology and thus overcome some of performance loss. This paper reviews the challenges of understanding grass-endophyte interactions, with particular attention to strategies of improving the performance of novel symbiota for agricultural purposes. Keywords: Lolium, Festuca, Neotyphodium, plant-endophyte interactions, symbiosis

Temperature Influences on Endophyte Growth in Tall Fescue

Tall fescue (Festuca arundinacea Schreb.) is the predominant perennial cool‐season grass grown in the USA. Typically, tall fescue is infected with the endophyte, Neotyphodium coenophialum Morgan‐Jones &amp; Gams, which produces alkaloids that are toxic to grazing animals. Nontoxic endophyte‐infected cultivars of tall fescue have been developed, but to maximize their utility for profitable livestock production a better understanding of conditions affecting seed and tiller transmission is needed to maintain endophytes in seed. Our understanding of mechanisms of endophyte transmission in planta is limited. Seasonal variations of endophyte in established tall fescue pastures in Watkinsville, GA, and seed fields near Salem, OR, were examined. Growth chamber experiments were conducted to examine temperature effects on plant and endophyte growth and to determine the cardinal minimum temperatures for each. Endophyte frequency varied over months in both Georgia and Oregon. Frequency averaged 93.4% when sampled April through December, but was 80.5% when sampled January through March in Georgia. Frequency averaged 64.5% when sampled February through April, but was 88.6% during other months in Oregon. Cardinal minimum temperature for plant growth was 5.2°C (± 0.5), but for endophyte was 10.3°C (± 0.7). Temperature appears to be a major variable affecting fluctuation of endophyte frequency in plant tissue.

The role of livestock in the management of dryland salinity

Management of dryland salinity in Australia will require changes in the design and utilisation of plant systems in agriculture. These changes will provide new opportunities for livestock agriculture. In areas already affected by salt, a range of plants can be grown from high feeding value legumes with moderate salt tolerance through to highly salt tolerant shrubs. A hectare of these plants may support between 500 and 2000 sheep grazing days per year. The type of plants that can be grown and the subsequent animal production potential depend on a range of factors that contribute to the ‘salinity stress index’ of a site, including soil and groundwater salinity, the extent and duration of waterlogging and inundation, the pattern and quantity of annual rainfall, soil texture and chemistry, site topography and other site parameters. Where the salinity stress index is high, plant options will usually include a halophytic shrub that accumulates salt. High salt intakes by grazing ruminants depress feed intake and production. Where high and low salt feeds are available together, ruminants will endeavour to select a diet that optimises the overall feeding value of the ingested diet. In areas that are not yet salt affected but contribute to groundwater recharge, perennial pasture species offer an opportunity for improved water and salt management both on-farm and at the catchments. If perennial pasture systems are to be adopted on a broad scale, they will need to be more profitable than current annual systems. In the high rainfall zones in Victoria and Western Australia, integrated bioeconomic and hydrological modelling indicates that selection of perennial pasture plants to match requirements of a highly productive livestock system significantly improves farm profit and reduces groundwater recharge. In the low to medium rainfall zones, fewer perennial plant options are available. However, studies aiming to use a palette of plant species that collectively provide resilience to the environment while maintaining profitable livestock production may also lead to new options for livestock in the traditional cropping zone.

Decision Support Systems for Profitable Livestock Production

The Agricultural and Related Industries Study Group of the Operational Research Society held a one-day meeting on ‘Decision Support Systems for Profitable Livestock Production’ on 18 November 1992 at the Meat and Livestock Commission, Milton Keynes, UK. The Group promotes the use of the scientific method in solving management problems. The aim of the meeting was to look at the contribution of advances in modelling towards improving management and hence profitability in livestock production. The first four papers concerned feeding and the remaining two breeding. A large part of the discussion could perhaps best be summed up by the regression equation which related dry matter intake and waste output from a cow. When the output was zero, the intake was reduced by 50%!