Effects of high ambient temperatures on the metabolism of West African dwarf goats. II

32 West African dwarf goats were exposed in respiration chambers to temperature treatments of 20, 25, 30, 35, 35, 35, 30, 25, 20°C. Each treatment lasted three days. 16 goats were kept in individual pens (I); the others in two group pens of eight animals each (G). During each treatment, heat production and activity were recorded continuously over 48 hours. In addition, feed and water intake, rectal temperature, skin temperature and respiratory rate were measured during each treatment.Compared to 20°C, at 35°C rectal temperature increased from 39.0°C to 39.9°C, respiratory rate from 30 to 260 times. min^–1 and skin temperature from 37.1°C to 39.5°C. Hay intake decreased by 40%; concentrates (30 g. kg^–0.75. d^–1) were always completely consumed. Heat production was higher for the G animals at 20°C and higher for the I animals at 35°C. These differences in heat production between the two groups were reflected in differences in rectal and skin temperature and in respiratory rate but only very slightly in differences in hay intake.Tissue insulation was 0.014 K. m². W^–1 at 30°C and 35°C and 0.022 K. m². W^–1 at 20°C.It is concluded that the reactions of these dwarf goats to high ambient temperatures are not different in principle from those of other domestic ruminants and that they do not exhibit a specific suitability or unsuitability for ambient temperatures as prevailing in West Africa.     

Effects of 2,4-dichlorophenoxyacetic acid on haematological indices in West African dwarf goats

We investigated the possible toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D) in West African dwarf goats. The goats (20) were randomly divided into four equal groups; three of which were exposed to graded levels (low, medium and high doses) of 2,4-D for a period of 6 weeks. Blood samples were collected from the treatment group goats as well as the control group goats on weeks 0, 2, 4 and 6. The blood samples were used for analysis of haematologic indices such as packed cell volume (PCV), erythrocyte count (EC), total leucocyte count (TLC), haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC). Total leucocyte counts were significantly reduced (p < 0.05) by the test herbicide (2,4-D) in all the treatment groups. Significant reduction in the levels of PCV, Hb concentration, MCV, MCH and MCHC were also recorded in all treatment groups. There was no significant change (p > 0.05) in the erythrocyte count value of all the four groups. The significant reduction in the haematologic indices of West African dwarf goats (WADG) as evidenced from the result of this study, suggest the possibility of 2,4-D toxicity in these goats.     

Behavioural interactions between West African dwarf nanny goats and their twin-born kids during the first 48 h post-partum

West African dwarf nanny goats and their twin-born kids were tested to determine their behavioural response to separation and their mutual recognition during the first 48 h post-partum. Does and their kids were given scores ranging from 1 to 5, depending on how they performed in the tests. Animals that showed maximum response and recognition ability were given a score of 5, while those with minimum response and recognition ability scored 1. The kids were prevented from sucking 2 h prior to the tests, which were carried out at 18, 24, 36 and 48 h post-partum. Chi-square procedure was used to determine whether age, sex and birthweight of kids as well as hours post-partum and parity of dams had any effect on these post-partum behaviours. Out of 48 twin-born kids tested, 32 (67%) responded actively to separation from dams (i.e. had scores of 3 or more). The age, sex and birthweight of kids did not significantly affect (P>0.05) their response to separation from their dams. The hours post-partum and the parity of does also did not affect their response to separation from their kids. The dam recognition ability of twin-born kids was very poor. Out of a total of 48 kids tested, only 17 (35%) were able to recognize their dams (i.e. had scores of 3 or more). Even at 36 h, only four out of 14 (26%) could recognize their dams. It was only at 48 h that the majority of kids tested (i.e. 75%) successfully identified their dams. At 48 h, the dam recognition ability of kids was significantly better (P<0.05) than that of 18-h-old kids. Sex and birthweight of 24-48-h-old twin-born kids did not significantly affect (P>0.05) their ability to recognize their dams. The majority of does tested (i.e. 20 out of 24) were able to recognize their twin-born kids. The hour post-partum and parity of does did not significantly affect (P>0.05) their kid recognition ability.     

Behavioural interactions between West African dwarf nanny goats and their single-born kids during the first 48 hours post-partum

West African dwarf nanny goats and their single-born kids were tested to find out their behavioural response to separation and their mutual recognition during the first 48 h post-partum. The tests were conducted at 18, 24, 36 or 48 h post partum. Chi-square analyses were used to determine whether age, sex and birth weight of kids as well as h partum and parity of dams had an effect on post-partum bahaviours.In a preliminary study where the kids were not prevented from sucking prior to the tests, the majority of kids (93%) and does (86%) exhibited apparant minimal concern to separation (i.e., had scores of less than 3) and also failed to seek each other. When the kids were prevented from sucking 2 h prior to the tests, the couple showed some response to separation and made attempts to seek each other. This suggests that in goats the state of the neonate's nourishment and the fullness of the dam's udder may be important factors that determine the willingness of the kid and the dam to seek each other when separated. The behavioural response of 48-h-old kids to separation from their dams when they had not sucked for 2 h was significantly higher (P<0.05) than that of 18-h-old kids. The sex and birth-weight of 48-h-old kids did not affect their response to separation from their dams. Hours post-partum and parity of does did not affect their response to separation from their kids even though the proportion of does exhibiting the highest response was much higher in primiparous then multiparous animals (44% vs. 13%). Recognition of dams by kids was poor at 18 and 24 h with more than half (71%) the kids failing to recognize their dams. Dam recognition ability improved with age and at 48 h the majority of kids (88%) were able to recognize their dams. Does tested at 48 h post partum had better (P0.05) kid recognition than those tested at 18 and 24 h. The sex and birth weight of kids and the parity of dams had no effect on the mutual recognition of kids and their dams at 48 h post-partum.     

Effects of an experimental Trypanosoma congolense infection on the reproductive performance of West African Dwarf goats

Thirty-six West African Dwarf (WAD) goats were used to assess the effects of an experimental Trypanosoma congolense infection on their reproductive system. Estrous cycles were synchronised and when confirmed pregnant (n = 31), the does were randomly allocated into control and trypanosome-infected groups. After infection, the animals were carefully observed till parturition. Trypanosome infection caused an increase of rectal temperature, a significant drop in PCV (infected: 23.3 +/- 0.3%; control: 28.5 +/- 0.4%; P < 0.0001) and abortions in 27.8% of the infected does. Kids born from infected does had a lower birth weight than kids born from control goats (0.9 +/- 0.1 kg versus 1.6 +/- 0.1 kg; P < 0.0001). Eight out of 13 kids (61.5%) that were born alive from infected does died during their first week of life. Plasma pregnancy-associated glycoprotein (PAG) and progesterone concentrations were lower in the infected animals than in the controls. In general, PAG concentration in does which aborted dropped before abortion. Our results revealed that artificial T. congolense infection affected reproductive performance of WAD goats with abortions, premature births and perinatal losses being observed. Neither transplacental transmission of T. congolense nor histopathological lesions of the placenta could be demonstrated.     

Fluid, electrolyte and haematological changes in experimental peste des petits ruminants virus infection in West African dwarf goats

The changes in plasma volume, blood volume, erythrocyte indices, leucocyte indices and serum biochemical values during experimental pestes des petits ruminants (PPR) virus infection of West African dwarf goats (Fouta djallon) were investigated. There was a progressive decline of the plasma volume and serum sodium and potassium values in all the infected goats as from day 5 post-infection and this became quite marked between days 10 and 23 post-infection. The fall was severest in those animals which had diarrhoea. There were no significant changes in the chloride, bicarbonate, phosphate, urea, total protein and albumin values of the goats during the course of the diseases. Haemoconcentration and apparent polycythaemia in the early and terminal stages of the disease were associated with severe dehydration which characterized the infection. There was initial neutrophilic leucocytosis during the phase of fever followed by marked lymphopaenic leucopaenia which progressed terminally in most of the infected goats. The destructive effect of the virus on lymphocytes is suggested as a cause of lymphopaenia.     

Changes in liver and fat depots of West African dwarf goats (Capra aegagus hircus) after an infection with T. vivax

Nine West African dwarf goats (Capra aegagus hircus) were each infected experimentally with 3 × 10⁷ Trypanosoma vivax parasites. The changes in the plasma concentration of nonesterified fatty acids (NEFA) were monitored during the infection and the level of hepatic triacylglycerols and glycogen was measured postmortem. During the infection they had higher plasma NEFA concentrations than nine uninfected control goats and at postmortem their total liver triacylglycerol and glycogen contents were found to be increased. These observations suggest that the mobilization of the goats' defense mechanisms against the T. vivax infection induced a more intensive fat mobilization resulting in changes in fat metabolism of the liver.     

Effects of ambient and preceding temperatures and metabolic genes on flight metabolism in the Glanville fritillary butterfly

Flight is essential for foraging, mate searching and dispersal in many insects, but flight metabolism in ectotherms is strongly constrained by temperature. Thermal conditions vary greatly in natural populations and may hence restrict fitness-related activities. Working on the Glanville fritillary butterfly (Melitaea cinxia), we studied the effects of temperature experienced during the first 2 days of adult life on flight metabolism, genetic associations between flight metabolic rate and variation in candidate metabolic genes, and genotype–temperature interactions. The maximal flight performance was reduced by 17% by 2 days of low ambient temperature (15 °C) prior to the flight trial, mimicking conditions that butterflies commonly encounter in nature. A SNP in phosphoglucose isomerase (Pgi) had a significant association on flight metabolic rate in males and a SNP in triosephosphate isomerase (Tpi) was significantly associated with flight metabolic rate in females. In the Pgi SNP, AC heterozygotes had higher flight metabolic rate than AA homozygotes following low preceding temperature, but the trend was reversed following high preceding temperature, consistent with previous results on genotype–temperature interaction for this SNP. We suggest that these results on 2-day old butterflies reflect thermal effect on the maturation of flight muscles. These results highlight the consequences of variation in thermal conditions on the time scale of days, and they contribute to a better understanding of the complex dynamics of flight metabolism and flight-related activities under conditions that are relevant for natural populations living under variable thermal conditions.     

Red cell metabolism in high and low glutathione goats.

The following biochemical features were measured in the red blood cells of high and low glutathione goats: reduced glutathione (GSH) stability; GSH regeneration; glucose consumption; lactate production; levels of adenosine triphosphate and 2,3-diphosphoglycerate, and the activities of nine different enzymes of Embden-Meyerhof and pentose phosphate pathways of glucose metabolism. Apart from significant differences in the GSH stability the results of all the tests were found to be similar in the two groups.     

Effects of apomorphine on thermoregulatory responses of rats to different ambient temperatures.

Either systemic or central administration of apomorphine produced dose-related decreases in rectal temperature at ambient temperatures (Ta) of 8 and 22 degrees C in rats. At Ta = 8 degrees C, the hypothermia was brought about by a decrease in metabolic rate (M). At Ta = 22 degrees C, the hypothermia was due to an increase in mean skin temperature, an increase in respiratory evaporative heat loss (Eres) and a decrease in M. This increased mean skin temperature was due to increased tail and foot skin temperatures. However, at Ta = 29 degrees C, apomorphine produced increased rectal temperatures due to increased M and decreased Eres. Moreover, the apomorphine-induced hypothermia or hyperthermia was antagonized by either haloperidol or 6-hydroxydopamine, but not by 5,6-dihydroxytryptamine. The data indicate that apomorphine acts on dopamine neurons within brain, with both pre- and post-synaptic sites of action, to influence body temperature.     

Ovarian activities of the West African dwarf goat (Capra hircus) during oestrus

Ovarian activity was studied by laparotomy of 9 adult nulliparous goats in which oestrus was synchronized. Ovulation occurred in animals operated on 20-48 h from the onset of sexual receptivity. There was a mean ovulation rate of 1.57 ova per doe and the right and left ovaries had similar follicular activity in relation to sizes of follicles and ovulations.     

Studies on the West African I strain of Plasmodium falciparum in Aotus trivirgatus monkeys.

The West African I strain of Plasmodium falciparum was isolated from a commercial airline pilot who had an overnight stay in Nigeria. Once established in the Aotus trivirgatus griseimembra monkey, the parasite produced high parasitemias and readily infected mosquitoes. Anopheles freeborni and An. maculatus mosquitoes transmitted the infection to additional animals. Infected salivary glands were also seen in An. culcifacies. Comparative infectivity studies indicated the most susceptible mosquito to be An. freeborni, followed by An. culicifacies, An. maculatus, and An. balabacensis balabacensis. Only 2 An. albimanus mosquitoes were infected out of 450 examined. The one A. t. trivirgatus monkey inoculated with this strain had very low levels of parasitemia.