The influence of diet and carnitine supplementation on plasma carnitine, cholesterol and triglyceride in WHHL (Watanabe-heritable hyperlipidemic), Netherland dwarf and New Zealand rabbits (Oryctolagus cuniculus)

1. Plasma carnitine levels in the spontaneously (endogenously) hyperlipidemic Watanabe (WHHL) rabbit are approximately 2-fold higher (P less than 0.001) than in normal rabbits of the New Zealand (NZ) or Netherland Dwarf (NDw) breeds. 2. Plasma carnitine levels in WHHL (44 +/- 3 nmol/ml) can be approximated in NZ and NDw which are rendered exogenously hyperlipidemic by supplementation of the stock chow diet with cholesterol and peanut oil. 3. The induction of endogenous hyperlipidemia in NZ by feeding a sucrose casein rich diet results in a biphasic response of plasma carnitine (elevation followed by normalization). 4. Plasma carnitine in WHHL is readily elevated by supplemental L-carnitine and the elevation is associated with a reduction in plasma triglyceride which shows differences in individual response time; plasma cholesterol is unaffected by supplemental L-carnitine.     

Influence of carnitine supplementation on muscle substrate and carnitine metabolism during exercise

We examined 1) the effect of L-carnitine supplementation on free fatty acid (FFA) utilization during exercise and 2) exercise-induced alterations in plasma levels and skeletal muscle exchange of carnitine. Seven moderately trained human male subjects serving as their own controls participated in two bicycle exercise sessions (120 min, 50% of VO2max). The second exercise was preceded by 5 days of oral carnitine supplementation (CS; 5 g daily). Despite a doubling of plasma carnitine levels, with CS, there were no effects on exercise-induced changes in arterial levels and turnover of FFA, the relation between leg FFA inflow and FFA uptake, or the leg exchange of other substrates. Heart rate during exercise after CS decreased 7-8%, but O2 uptake was unchanged. Exercise before CS induced a fall from 33.4 +/- 1.6 to 30.8 +/- 1.0 (SE) mumol/l in free plasma carnitine despite a release (2.5 +/- 0.9 mumol/min) from the leg. Simultaneously, acylated plasma carnitine rose from 5.0 +/- 1.0 to 14.2 +/- 1.4 mumol/l, with no evidence of leg release. Consequently, total plasma carnitine increased. We concluded that in healthy subjects CS does not influence muscle substrate utilization either at rest or during prolonged exercise and that free carnitine released from muscle during exercise is presumably acylated in the liver and released to plasma.     

Distribution and ecology of ticks (Acari: Ixodidae) infesting livestock in Tunisia: an overview of eighth years field collections

Ticks (Ixodidae) play a significant role as vectors of pathogens of domestic animals in Tunisia. The major losses caused by ticks are related to transmission of protozoan parasites. These include agents of tropical theileriosis and babesiosis in ruminants. Since 1991, we conducted research studies on tick population of livestock in Tunisia. This overview reports a synthesis on tick distribution, their biology and their role as vectors of pathogens in domestic animals, particularly cattle. During the whole period of the study about 15,000 tick specimens were collected from different zones of the country. A total of 14 species were identified. Hyalomma detritum detritum was the most abundant and important (vector of Theileria annulata) species infesting cattle. Hyalomma dromedarii and Hyalomma impeltatum were collected on domestic ruminants in the arid and desertic zones. Hyalomma marginatum marginatum and Hyalomma anatolicum excavatum were widespread and found on livestock hosts. Ixodes ricinus, vector of Babesia divergens and Borrelia burgdorferi sl, colonises mainly the humid zone. Boophilus annulatus and Rhipicephalus bursa infesting cattle, sheep and goats were found in the sub-humid and semi-arid zones. Haemaphysalis sulcata and Hae. punctata were collected in humid and sub-humid zones on cattle and sheep. Rhipicephalus turanicus were collected in different regions, on different animal species. Rhipicephalus sanguineus, tick of dogs, were often collected on livestock. Only few specimens of Hyalomma marginatum rufipes and Hyalomma franchinii were collected.     

Crimean-Congo hemorrhagic fever virus antibody prevalence in Mauritanian livestock (cattle,goats, sheep and camels) is stratified by the animal’s age

Crimean-Congo hemorrhagic fever virus (CCHFV) is one of the most widespread zoonotic arthropod-borne viruses in many parts of Africa, Europe and Asia. It belongs to the family of Nairoviridae in the genus of Orthonairovirus. The main reservoir and vector are ticks of the genus Hyalomma. Livestock animals (such as cattle, small ruminants and camels) develop a viremias lasting up to two weeks with absence of clinical symptoms, followed by seroconversion. This study was carried out to assess risk factors that affect seroprevalence rates in different species. In total, 928 livestock animal samples (cattle = 201; sheep = 247; goats = 233; camels = 247) from 11 out of 13 regions in Mauritania were assayed for CCHFV-specific immunoglobulin G (IgG) antibodies using enzyme-linked immunosorbent assays (ELISA) (including a novel indirect camel-IgG-specific CCHFV ELISA). Inconclusive results were resolved by an immunofluorescence assay (IFA). A generalized linear mixed-effects model (GLMM) was used to draw conclusions about the impact of certain factors (age, species, sex and region) which might have influenced the CCHFV antibody status of surveyed animals. In goats and sheep, about 15% of the animals were seropositive, whereas in cattle (69%) and camels (81%), the prevalence rate was significantly higher. On average, cattle and camels were up to twice to four times older than small ruminants. Interestingly, the seroprevalence in all species was directly linked to the age of the animals, i.e. older animals had significantly higher seroprevalence rates than younger animals. The highest CCHFV seroprevalence in Mauritania was found in camels and cattle, followed by small ruminants. The large proportion of positive animals in cattle and camels might be explained by the high ages of the animals. Future CCHFV prevalence studies should at least consider the age of surveyed animals in order to avoid misinterpretations.     

Large variations in skeletal muscle carnitine level fail to modify energy metabolism in exercising rats

1. The importance of carnitine status in energy metabolism during exercise was studied in experimentally carnitine-depleted or supplemented rats. 2. Muscle carnitine concentration can be decreased by 40% with D-carnitine and increased by 40% with L-carnitine supplementation. 3. In spite of large variation of carnitine content, neither the exercising capacity nor the rate of muscle or liver glycogenolysis were modified during submaximal exercise. 4. The increased lipid metabolism induced by exercise can be adequately supported by endogenous levels of tissue carnitine. 5. Before any impairment in energy metabolism during exercise can be demonstrated, carnitine concentration has to be reduced to a level close to that measured with primary carnitine deficiency, i.e. less than 20 mumol/l of plasma.     

Drug resistance in nematodes of veterinary importance: a status report

Reports of drug resistance have been made in every livestock host and to every anthelmintic class. In some regions of world, the extremely high prevalence of multi-drug resistance (MDR) in nematodes of sheep and goats threatens the viability of small-ruminant industries. Resistance in nematodes of horses and cattle has not yet reached the levels seen in small ruminants, but evidence suggests that the problems of resistance, including MDR worms, are also increasing in these hosts. There is an urgent need to develop both novel non-chemical approaches for parasite control and molecular assays capable of detecting resistant worms.     

Effect of various levels of supplementation with sodium pivalate on tissue carnitine concentrations and urinary excretion of carnitine in the rat

In previous studies, sodium pivalate has been administered to rats in their drinking water (20 mmoles/L; equivalent to 0.3% of the diet) as a way to lower the concentration of carnitine in tissues and to produce a model of secondary carnitine deficiency. Although this level of supplementation results in a marked decrease in carnitine concentration in a variety of tissues, it does not produce the classical signs of carnitine deficiency (i.e., decreased fatty acid oxidation and ketogenesis). The present study was designed (1) to determine if increasing the level of pivalate supplementation (0.6, 1.0% of the diet) would further reduce the concentrations of total and free carnitine in rat tissues without altering growth or food intake, and (2) to examine the effect of length of feeding (4 vs. 8 weeks) on these variables. Male, Sprague-Dawley rats were randomly assigned to either a control (0.2% sodium bicarbonate) or experimental diet (0.3, 0.6, 1.0% sodium pivalate) for either four or eight weeks. Animals (n = 6/group) were housed in metabolic cages; food and water were provided ad libitum throughout the study. Supplementation with sodium pivalate did not alter water intake or urine output. Ingestion of a diet containing 1.0% pivalic acid decreased food intake (g/day; P < 0.05), final body weight (P < 0.007), and growth rate (P < 0.001) after four weeks. The concentration of total carnitine in plasma, heart, liver, muscle, and kidney was reduced in all experimental groups (P < 0.001), regardless of level of supplementation or length of feeding. The concentration of free carnitine in heart, muscle, and kidney was also reduced (P < 0.001) in rats treated with pivalate for either four or eight weeks. The concentration of free carnitine in liver was reduced in animals supplemented with pivalate for eight weeks (P < 0.05), but no effect was observed in livers from rats treated for four weeks. Excretion of total carnitine and short chain acylcarnitine in urine was increased in pivalate supplemented rats throughout the entire feeding period (P < 0.001). Free carnitine excretion was increased during Weeks 1 and 2 (P < 0.01), but began to decline during Week 3 in experimental groups. During Weeks 6 and 8, free carnitine excretion in pivalate supplemented rats was less than that of control animals (P < 0.01). In summary, no further reduction in tissue carnitine concentration was observed when rats were supplemented with sodium pivalate at levels greater than 0.3% of the diet. Food intake (g/day) and growth were decreased in rats fed a diet containing 1.0% sodium pivalate. These data indicate that maximal lowering of tissue carnitine concentrations is achieved by feeding diets containing 0.3% sodium pivalate or less.     

Ruminant brucellosis in the Kafr El Sheikh Governorate of the Nile Delta, Egypt: prevalence of a neglected zoonosis

BACKGROUND: Brucellosis is a neglected tropical zoonosis allegedly reemerging in Middle Eastern countries. Infected ruminants are the primary source of human infection; consequently, estimates of the frequency of ruminant brucellosis are useful elements for building effective control strategies. Unfortunately, these estimates are lacking in most Middle East countries including Egypt. Our objectives are to estimate the frequency of ruminant brucellosis and to describe its spatial distribution in Kafr El Sheikh Governorate, Nile Delta, Egypt. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a cross-sectional study in which 791 sheep, 383 goats, 188 cattle milk tanks and 173 buffalo milk tanks were randomly selected in 40 villages and tested for the presence of antibodies against Brucella spp. The seroprevalence among different species was estimated and visualized using choropleth maps. A spatial scanning method was used to identify areas with significantly higher proportions of seropositive flocks and milk tanks. We estimated that 12.2% of sheep and 11.3% of goats in the study area were seropositive against Brucella spp. and that 12.2% and 12% of cattle and buffalo milk tanks had antibodies against Brucella spp. The southern part of the governorate had the highest seroprevalence with significant spatial clustering of seropositive flocks in the proximity of its capital and around the main animal markets. CONCLUSIONS/ SIGNIFICANCE: Our study revealed that brucellosis is endemic at high levels in all ruminant species in the study area and questions the efficacy of the control measures in place. The high intensity of infection transmission among ruminants combined with high livestock and human density and widespread marketing of unpasteurized milk and dairy products may explain why Egypt has one of the highest rates of human brucellosis worldwide. An effective integrated human-animal brucellosis control strategy is urgently needed. If resources are not sufficient for nationwide implementation, high-risk areas could be prioritized.     

The role of omega-3 polyunsaturated fatty acids in reproduction of sheep and cattle

The positive effects of fat and energy supplementation on improvements in reproduction are well documented. However, the specific effects of omega-3 polyunsaturated fatty acids (n-3) on reproductive success in ruminants have not been examined in detail. While the link between n-3 and markers associated with reproduction, in particular, prostaglandin F(2α) (PGF(2α)) and the link between PGF(2α) and reproductive outcomes are well established, evidence of a direct effect of high n-3 diets on measurable reproductive outcomes in ruminants is lacking. Therefore, the aim of the current review was to examine the effect of n-3 on a number of reproductive markers and measurable outcomes in sheep and cattle. There is strong evidence linking consumption of diets high in n-3 with reduced circulating peripheral inflammatory markers such as PGF(2α). Inflammatory eicosanoids including PGF(2α), in particular, can significantly affect reproduction outcomes such as the onset of oestrus, embryo survival and parturition. While there is also evidence linking n-3 supplementation with longer time to oestrus and parturition associated with reduced PGF(2α), the effects of n-3 on other measurable outcomes of reproductive success, such as pregnancy rate, embryo survival and intergenerational effects on the health and production of offspring are largely unknown. Similarly, the effects of diets high in n-3 or n-6 polyunsaturated fatty acids on male fertility are also unknown.     

Differential excretion of xenobiotic acyl-esters of carnitine due to administration of pivampicillin and valproate

The fate of supplemental carnitine was studied in human subjects treated with drugs known to cause carnitine deficiency. Six children were treated with pivampicillin and equimolar L-carnitine for 7 days. On the last day of treatment, the plasma levels of total and free carnitine were decreased, but acylcarnitine levels were increased. A 12-fold increase in urinary excretion of acylcarnitines was found; it increased from 188.5 +/- 82.7 to 2218.4 +/- 484.1 mumole/day, and 84% was pivaloylcarnitine. Free carnitine excretion was reduced. Ten epileptic children on chronic valproate treatment received equimolar carnitine for a 2-week period. Plasma carnitine levels were elevated on the last day of treatment. A 3.4-fold increase in urinary acylcarnitines was found, but most of the excreted carnitines were free (64.5-fold increases). These data show that pivalate is readily converted to carnitine esters, in contrast to the limited conversion of valproate to acylcarnitines in humans.     

Stereopharmacology of carnitine

L-Carnitine (L-beta-hydroxy-gamma-N,N,N-trimethylaminobutyric acid) plays an essential role in fatty acid transport in the mitochondrion. Conditions that appear to benefit from exogenous supplementation of L-carnitine include anorexia, chronic fatigue, cardiovascular disease, hypoglycemia, male infertility, muscular myopathies, renal failure and dialysis. D-Carnitine is not biologically active and might interfere with the proper utilization of the L isomer, and so there are claims that the racemic mixture (DL-carnitine) should be avoided. Despite the fact that it is known about the systemic manifestations of oral intake of this compound, oral supplementation with DL-carnitine for treatment of primary and secondary carnitine deficiency syndromes has been used in Russia for 25 years. The purpose of the present review was to contrast the differences in pharmacokinetics, phannacodynamics, biochemistry, and toxicity between treatments of L- and DL-carnitine. There is some evidence that L-carnitine and D-carnitine compete for uptake in small intestine and tubular re-absorption in kidneys. After intestinal absorption, L- and D-carnitine is transferred to organs whose metabolism is dependent on fatty acid oxidation, such as heart and skeletal muscle, and D-carnitine competitively depletes muscle level of L-carnitine. Whereas L-carnitine is found to be essential for the oxidation of fatty acids, D-carnitine causes a depletion of L-carnitine, and hindered fatty acid oxidation and energy formation. Pharmacological effects of carnitine are stereospecific, since L-carnitine was effective in various animals and clinical studies, while D- and DL-carnitine was found to be ineffective or toxic, for example, to muscle cells and to the myocardium. DL-Carnitine causes symptoms of myasthenia and cardiac arrhythmias, which disappeared after L-carnitine administration. Clinically toxic effect of D-carnitine was described in patients with renal failure on long-term haemodialysis, in adriamycin (doxorubicin) cardiotoxicity and in stable angina pectoris.     

Aspects of carnitine ester metabolism in sheep liver

1. Carnitine acetyltransferase (EC 2.3.1.7) activity in sheep liver mitochondria was 76nmol/min per mg of protein, in contrast with 1.7 for rat liver mitochondria. The activity in bovine liver mitochondria was comparable with that of sheep liver mitochondria. Carnitine palmitoyltransferase activity was the same in both sheep and rat liver mitochondria. 2. The [free carnitine]/[acetylcarnitine] ratio in sheep liver ranged from 6:1 for animals fed ad libitum on lucerne to approx. 1:1 for animals grazed on open pastures. This change in ratio appeared to reflect the ratio of propionic acid to acetic acid produced in the rumen of the sheep under the two dietary conditions. 3. In sheep starved for 7 days the [free carnitine]/[acetylcarnitine] ratio in the liver was 0.46:1. The increase in acetylcarnitine on starvation was not at the expense of free carnitine, as the amounts of free carnitine and total acid-soluble carnitine rose approximately fivefold on starvation. An even more dramatic increase in total acid-soluble carnitine of the liver was seen in an alloxan-diabetic sheep. 4. The [free CoA]/[acetyl-CoA] ratio in the liver ranged from 1:1 in the sheep fed on lucerne to 0.34:1 for animals starved for 7 days. 5. The importance of carnitine acetyltransferase in sheep liver and its role in relieving ;acetyl pressure' on the CoA system is discussed.     

Acetyl-L-carnitine supplementation restores decreased tissue carnitine levels and impaired lipid metabolism in aged rats

The effects of long-term carnitine supplementation on age-related changes in tissue carnitine levels and in lipid metabolism were investigated. The total carnitine levels in heart, skeletal muscle, cerebral cortex, and hippocampus were approximately 20% less in aged rats (22 months old) than in young rats (6 months old). On the contrary, plasma carnitine levels were not affected by aging. Supplementation of acetyl-l-carnitine (ALCAR; 100 mg/kg body weight/day for 3 months) significantly increased tissue carnitine levels in aged rats but had little effect on tissue carnitine levels in young rats. Plasma lipoprotein analyses revealed that triacylglycerol levels in VLDL and cholesterol levels in LDL and in HDL were all significantly higher in aged rats than in young rats. ALCAR treatment decreased all lipoprotein fractions and consequently the levels of triacylglycerol and cholesterol. The reduction in plasma cholesterol contents in ALCAR-treated aged rats was attributable mainly to a decrease of cholesteryl esters rather than to a decrease of free cholesterol. Another remarkable effect of ALCAR was that it decreased the cholesterol content and cholesterol-phospholipid ratio in the brain tissues of aged rats. These results indicate that chronic ALCAR supplementation reverses the age-associated changes in lipid metabolism.     

L-carnitine increases liver alpha-tocopherol and lowers liver and plasma triglycerides in aging ovariectomized rats

The objective of this study was to determine whether dietary L-carnitine can influence the status of alpha-tocopherol, retinol and selected lipid parameters in aging ovariectomized rats, an animal model for the menopausal state. Fourteen Fisher-344 female rats 18 months old were acclimated for 4 weeks and ovarectomized. Seven rats per treatment were assigned to either a control group fed ad libitum AIN-93M diet or a carnitine group fed the same diet supplemented with L-carnitine. After an 8-week feeding period, blood and selected tissues were taken for analyses. No differences were noted in food intake, body weight, or organ weights due to L-carnitine. Dietary carnitine significantly increased liver alpha-tocopherol and tended to increase plasma alpha-tocopherol (P<.09). No changes in alpha-tocopherol were observed in other tissues including the brain, lungs and retroperitoneal fat. Retinol levels in plasma and tissues were not affected by supplemental L-carnitine. Significant decreases in liver and plasma triglyceride (TG) levels were noted, suggesting increased utilization of fatty acids. No differences were observed in the fatty acid profile of tissues. The results provide evidence that dietary supplementation of L-carnitine enhances the alpha-tocopherol status and improves the utilization of fat leading to lowering of the liver and plasma levels of TG in aging ovariectomized rats. Whether supplemental L-carnitine may be of benefit to postmenopausal women in lowering plasma TG and improving the antioxidant status remains to be studied.     

Resource use efficiency in urban and peri-urban sheep, goat and cattle enterprises

Urban livestock husbandry receives growing attention given the increasing urban demand for livestock products. At the same time, little is known about the resource use efficiency in urban livestock enterprises and eventual negative externalities. In livestock production, feeds are an important resource whose nutrients are transformed into products (meat and milk) to generate financial return to the producer. The lack of knowledge on nutrient supply through feed might lead to oversupply with severe environmental impacts. In Niamey, a typical West African city and capital of the Republic of Niger, urban livestock production is constrained by feed scarcity, especially during the dry season. Here, the issue of resource use efficiency was studied in 13 representative and differently managed sheep/goat and cattle enterprises characterized by high and low feed inputs, respectively, during a period of 28 months. Nitrogen (N), phosphorus (P) and potassium (K) inflows into each farm through livestock feeds and outflows through manure were determined using a semi-structured questionnaire; interviews were accompanied by regular weighing of feed supplied and dung produced. Live weight gain (LWG) and efficiency of conversion of total feed dry matter offered (kg TDMO/kg LWG) were computed along with nutrient balances (NBs) per metabolic body mass (kg0.75). NBs (per kg0.75/day) in the high-input (HI) sheep/goat enterprises were +1762.4 mg N, +127.2 mg P and +1363.5 mg K and were significantly greater (P < 0.05) than those in low-input (LI) units (+69.1 mg N, -98.3 mg P and +16.5 mg K). In HI cattle enterprises, daily balances averaged +454.1 mg N, +40.1 mg P and +341.8 mg K compared to +34.4 mg N, -9.0 mg P and +68.3 mg K (P > 0.05) in LI cattle systems. All systems were characterized by poor conversion efficiencies of offered feed, which ranged from 13.5 to 46.1 kg TDMO/kg LWG in cattle and from 15.7 to 43.4 kg TDMO/kg LWG in sheep/goats. LWG in HI sheep/goats was 53 g/day in the rainy season, 86 g/day in the hot dry season and 104 g/day in the cool dry season, while HI cattle lost 79 g/day in the hot dry season and gained 121 g/day and 92 g/day in the cool dry and rainy seasons, respectively. The data indicate that there is nutrient wasting and scope for improvement of feeding strategies in Niamey's livestock enterprises, which might also decrease nutrient losses to the urban environment.     

Effect of L-Carnitine Supplementation on Utilisation of Energy and Protein in Broiler Chicken Fed Different Dietary Fat Levels

Effects of a supplementation of 80mg L-carnitine perkg diet were studied in broiler chicken at two dietary levels of fat (4 and 8 %) and different feeding levels (ad libitum in a growth trial, 95 and 85 % of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

A Serological Survey of Ruminant Livestock in Kazakhstan During Post-Soviet Transitions in Farming and Disease Control

The results of a serological survey of livestock in Kazakhstan, carried out in 1997–1998, are reported. Serum samples from 958 animals (cattle, sheep and goats) were tested for antibodies to foot and mouth disease (FMD), bluetongue (BT), epizootic haemorrhagic disease (EHD), rinderpest (RP) and peste des petits ruminants (PPR) viruses, and to Brucella spp. We also investigated the vaccination status of livestock and related this to changes in veterinary provision since independence in 1991. For the 2 diseases under official surveillance (FMD and brucellosis) our results were similar to official data, although we found significantly higher brucellosis levels in 2 districts and widespread ignorance about FMD vaccination status. The seroprevalence for BT virus was 23%, and seropositive animals were widespread suggesting endemicity, despite the disease not having being previously reported. We found a few seropositives for EHDV and PPRV, which may suggest that these diseases are also present in Kazakhstan. An hierarchical model showed that seroprevalence to FMD and BT viruses were clustered at the farm/village level, rather than at a larger spatial scale. This was unexpected for FMD, which is subject to vaccination policies which vary at the raion (county) level.     

Mitigating climate change: the role of domestic livestock

Livestock contribute directly (i.e. as methane and nitrous oxide (N2O)) to about 9% of global anthropogenic greenhouse gas (GHG) emissions and around 3% of UK emissions. If all parts of the livestock production lifecycle are included (fossil fuels used to produce mineral fertilizers used in feed production and N2O emissions from fertilizer use; methane release from the breakdown of fertilizers and from animal manure; land-use changes for feed production and for grazing; land degradation; fossil fuel use during feed and animal production; fossil fuel use in production and transport of processed and refrigerated animal products), livestock are estimated to account for 18% of global anthropogenic emissions, but less than 8% in the UK. In terms of GHG emissions per unit of livestock product, monogastric livestock are more efficient than ruminants; thus in the UK, while sheep and cattle accounted for 32% of meat production in 2006, they accounted for 48% of GHG emissions associated with meat production. More efficient management of grazing lands and of manure can have a direct impact in decreasing emissions. Improving efficiency of livestock production through better breeding, health interventions or improving fertility can also decrease GHG emissions through decreasing the number of livestock required per unit product. Increasing the energy density of the diet has a dual effect, decreasing both direct emissions and the numbers of livestock per unit product, but, as the demands for food increase in response to increasing human population and a better diet in some developing countries, there is increasing competition for land for food v. energy-dense feed crops. Recalculating efficiencies of energy and protein production on the basis of human-edible food produced per unit of human-edible feed consumed gave higher efficiencies for ruminants than for monogastric animals. The policy community thus have difficult decisions to make in balancing the negative contribution of livestock to the environment against the positive benefit in terms of food security. The animal science community have a responsibility to provide an evidence base which is objective and holistic with respect to these two competing challenges.     

PPAR alpha-activation results in enhanced carnitine biosynthesis and OCTN2-mediated hepatic carnitine accumulation

In fasted rodents hepatic carnitine concentration increases considerably which is not observed in PPAR alpha-/- mice, indicating that PPAR alpha is involved in carnitine homeostasis. To investigate the mechanisms underlying the PPAR alpha-dependent hepatic carnitine accumulation we measured carnitine biosynthesis enzyme activities, levels of carnitine biosynthesis intermediates, acyl-carnitines and OCTN2 mRNA levels in tissues of untreated, fasted or Wy-14643-treated wild type and PPAR alpha-/- mice. Here we show that both enhancement of carnitine biosynthesis (due to increased gamma-butyrobetaine dioxygenase activity), extra-hepatic gamma-butyrobetaine synthesis and increased hepatic carnitine import (OCTN2 expression) contributes to the increased hepatic carnitine levels after fasting and that these processes are PPAR alpha-dependent.