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1.
To investigate the effects of inoculants and environmental temperature on fermentation quality and bacterial diversity of alfalfa silage, first‐cut alfalfa was ensiled with or without two screened lactic acid bacteria (LAB) strains, Lactobacillus plantarum, LP, and Lactobacillus casei, LC. Each treatment was divided into three parts and stored at 20°C, 30°C, 40°C, respectively. After 60 days ensiling, fermentation characteristics were measured and bacterial diversity was investigated by 16S ribosomal RNA gene sequencing using Illumina MiSeq platform. LP and LC decreased pH, coliform bacteria counts and increased lactic acid content at 20°C, and the two strains decreased pH, ammonia‐N concentration, coliform bacteria counts at 30°C. When the environmental temperature was 40°C, silage treated with LC showed lower LAB and coliform bacteria counts and higher lactic acid content than the untreated and LP treated silages. Butyric acid mainly appeared in silages stored at 40°C. The relative abundance of Lactobacillus in alfalfa silages stored at 20°C and 30°C was highest and increased after LP and LC were added. Garciella was another dominant genus in silages stored at 40°C. In conclusion, LP and LC improved fermentation quality of alfalfa silage by increasing Lactobacillus proportions at 20°C and 30°C; ensiling alfalfa at 40°C was difficult because of Garciella.  相似文献   

2.
Twenty-four adult cats were transitioned to time-limited feeding and randomized to either a dry low carbohydrate diet (LC) or a dry reduced energy diet (HC). In Trial 1 the LC and HC groups received equal amounts of food (by weight) for 13 weeks. Both groups consumed all food offered, hence the LC group received more energy/day than the HC group. In Trial 2 all cats were fed the LC diet for 12 weeks, but each group received the energy that the opposite group had received in Trial 1. In Trial 1 only the overweight HC cats (body condition score> 6/9) experienced a significant change in body weight (-0.52 +/- 0.08 kg). In Trial 2, LC/Low Calorie overweight cats lost 0.62 +/- 0.10 kg, whereas, the LC/High Calorie normal weight cats gained 0.68 +/- 0.05 kg. In conclusion, body condition and energy intake but not type of diet influenced weight in this cohort of group-housed cats.  相似文献   

3.
1. Male broilers (n = 1521) from 247 families were reared from 4 to 6 weeks of age at 22° or 32°C. 2. Genetic correlations between measurements recorded at 22°C and 32°C were 0.73 ± 0.12 for weight gain between 4 and 6 weeks and 0.74 ± 0.08 for food conversion ratio (FCR). Genes controlling weight gain at both temperatures differed to some extent. 3. Heritability of weight gain from 4 to 6 weeks was much lower at 32°C than at 22°C (0.13 ± 0.03 vs 0.24 ± 0.04): selection for increased body weight will thus be much less efficient at 32°C than at 22°C. 4. Conversely, heritabilities of the FCR were very similar at the 2 temperatures (0.28 ± 0.04 at 22°C and 0.27 ± 0.04 at 32°C). Selecting for FCR would thus be efficient at 32°C too. 5. These results justify, at least under our experimental conditions, selecting broiler lines for improved growth performance at 22°C. However, it could be more efficient if broilers are to be reared in hot climates to select for improved FCR rather than for increased body weight.  相似文献   

4.
An experimental investigation revealed that cocoon production by E. foetida (Oligochaeta) increased linearly with increase in temperature in the range 10 to 25 °C. Diurnally fluctuating temperature did not have a marked influence on total cocoon production at the temperature levels of 10, 15 and 25 °C. A highly significant difference in cocoon production occurred between a constant temperature of 20 °C and a mean temperature of 20 °C (which fluctuated diurnally between 12 and 28 °C). Maximum cocoon production was obtained at 25 °C with each worm producing a cocoon every second day. The investigation also showed that temperature does influence the number of hatchlings per cocoon. At a temperature of 25 °C fewer worms hatched per cocoon than at 20 °C.  相似文献   

5.
A feeding trial of 70‐days was carried out to study the haemato‐immunological and stress responses of Labeo rohita fingerlings reared at two water temperatures [ambient (Amb) – 27 °C and 32 °C] fed with graded levels of gelatinized corn carbohydrate (GC). Two hundred and sixteen fingerlings were randomly distributed into six treatment groups in triplicate. Three semi‐purified diets were prepared containing 30% crude protein with graded levels of GC 40%, 50% and 58%. The six treatment groups were T1 (40% GC × Amb), T2 (40% GC × 32 °C), T3 (50% GC × Amb), T4 (50% GC × 32 °C), T5 (58% GC × Amb) and T6 (58% GC × 32 °C). The blood glucose level was significantly (p < 0.05) lowered in groups fed with 58% GC level. Neither dietary GC levels nor temperature had a significant (p > 0.05) effect on serum cortisol and superoxide dismutase activity. Lysozyme activity was significantly higher (p < 0.05) in T1 during pre‐ and post‐challenge period while temperature alone had a significant (p < 0.05) effect on post‐challenge Nitroblue Tetrazolium and found higher at 32 °C. A significant effect of GC levels and rearing temperature was recorded on WBC in the pre‐ and post‐challenge period. Highest pre‐challenge WBC was observed in T4 group and in the post‐challenge period T1 group recorded maximum. Water temperature had significant effect on pre‐challenge haemoglobin content, highest being at 32 °C (T2). A significant (p < 0.05) effect of rearing temperature and dietary GC level on total serum protein and albumin was also observed. Highest total serum protein and albumin was recorded in T1 and globulin in T2. Percentage survival after challenging with Aeromonas hydrophila was highest in T1 followed by T3 group and lowest in T6. The results obtained in the present study suggest that L. rohita fingerlings may utilize higher levels of dietary GC at higher temperature (32 °C) but may affect its immunity status.  相似文献   

6.
本试验旨在研究枯草芽孢杆菌CGMCC 1.921对蛋鸡生产性能、血常规指标、血清生化指标及免疫球蛋白含量的影响。选用27周龄健康的海兰褐壳蛋鸡360只,随机分为5个组,每个组6个重复,每个重复12只鸡。对照组(1组)饲喂基础饲粮,试验组(2~5组)分别在基础饲粮中添加1.0×105、1.0×106、1.0×107和1.0×108CFU/g枯草芽孢杆菌CGMCC 1.921。试验期24周。结果表明:各组产蛋率、采食量、蛋重、只产蛋量及死淘率均无显著差异(P0.05),但试验2、4、5组料蛋比显著低于对照组(P0.05);饲粮添加枯草芽孢杆菌CGMCC 1.921显著升高了血清葡萄糖含量(第2、3、12、16、20周)(P0.05),显著降低了血清尿素含量(第2、3、8、12周)(P0.05);饲粮添加枯草芽孢杆菌CGMCC 1.921显著提高了血液白细胞(第1、3、4、8、12、16、20、24周)和淋巴细胞数目(第2、3、4、8、12、16、20、24周)(P0.05),显著升高了血清免疫球蛋白G(第1、4周)和免疫球蛋白M含量(第2、4、8、16周)(P0.05)。综上所述,饲粮中添加枯草芽孢杆菌CGMCC 1.921降低了料蛋比,对血清葡萄糖、尿素含量和血常规指标指标有一定改善作用,且在一定程度上促进了蛋鸡免疫力的提升。  相似文献   

7.
The relationship of serum cortisol to immunoglobulin absorption and gut closure in cesarean-derived neonatal lambs was evaluated in two trials. In trial 1, 21 lambs were obtained on d 136 to 138 of gestation, and in trial 2, 17 lambs were obtained on d 140 to 142 of gestation. At birth, lambs were assigned randomly to four treatments: 1) control (CO), 1 ml saline/kg BW every 4 h; 2) a drug to lower cortisol (LC), 5 mg metyrapone/kg BW every 4 h; 3) single-peak cortisol (SP), 10 IU ACTH/kg BW at 0 h; or 4) elevated cortisol (HC), 5 mg cortisol/kg BW every 4 h in trial 1 or 10 IU ACTH/kg BW every 4 h in trial 2. The treatment period was 24 and 48 h after delivery for trial 1 and 2, respectively. Lambs were fed pooled bovine colostrum every 4 h for 48 h after birth at 2 and 3.5% BW for trial 1 and 2, respectively. Compared with CO, HC increased serum cortisol, LC decreased serum cortisol and SP elevated serum cortisol concentrations through at least 8 h for both trials. In trial 1, HC and SP lambs exhibited elevated serum IgG, IgM and IgA concentrations by 20 h compared with CO. However, no difference in serum immunoglobulin concentration was observed at 36 h among CO, HC and SP. Conversely, LC had the lowest immunoglobulin concentration at 36 and 48 h, and precocious closure to immunoglobulin absorption had occurred by 20 h (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
An 8-week trial was conducted between March and May (hot-dry season) to determine effects of water temperature, feather clipping and aspirin on egg production of chickens. The treatments tested were hens given ordinary drinking water (control), cool water (100 g ice block per L) and aspirin (0.3 mg per L of ordinary water) and hens whose feathers were clipped (about two thirds of body feathers clipped). At 32 weeks of age, 120 Lohmann brown layer chickens of similar live weights were randomly divided into 12 groups of ten hens each and assigned to the treatments in triplicate using a completely randomized design. Feed and water were given ad libitum. Data included feed intake, water consumption, hen-day egg production and egg weight. Ambient house temperature, hen’s cloacal temperature and water temperature were monitored daily during the experimental period. Mean daily ambient temperature increased from 28.4 to 35.0 °C during the study period with consequent increase in cloacal temperatures (40.31 to 41.18 °C) of hens, ordinary drinking water and cool water. None of the treatments had any significant (P?>?0.05) effects on feed intake and water consumption of the birds. Hens given cool water produced more (P?P?P?>?0.05). It is concluded that the provision of cool water in a hot-dry climate had a beneficial effect on egg laying performance of chickens.  相似文献   

9.
There are instances where shell eggs may be moved from refrigeration into ambient temperature with high humidity, such as before wash and during transportation. Under these conditions, it is of concern that bacteria on wet eggs can grow and migrate through the shell pores into the egg. Objectives of this experiment were: 1) to compare 3 methods of quantifying condensate on eggs and 2) to quantify condensate on refrigerated shell eggs at 2 temperatures (22°C and 32°C). For objective 1, 270 fresh shell eggs (3 replications, 90 eggs per replication) were stored at 4°C, 60% relative humidity (RH), then placed at 22°C, 60% RH for 1 h. After this time, 30 pre-weighed eggs were randomly selected and weighed. Thirty eggs were thoroughly wiped with pre-weighed paper towels to collect condensate. Thirty eggs were evaluated with a pinless moisture meter for quantifying egg condensate, which was found to be an ineffective method. There was no difference in quantifying egg condensation by egg weight or weight of moisture absorbed on a paper towel (0.2% vs. 0.19% percentage gain mL condensation/egg surface area) (P > 0.05). For objective 2, 104 fresh eggs formed condensation at 2 temperatures (22°C and 32°C, 60% RH). Each egg weight was continuously recorded from the beginning of condensation formation to the point where the egg reached a constant weight. There was a difference found in the time it took for an egg to reach maximum condensation (11 min at 32°C, 17 min at 22°C), as well as completely dry (25 min at 32°C, 34 min at 22°C) between the 2 temperatures (P < 0.05).  相似文献   

10.
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11.
1. Heterozygous naked neck birds were raised under natural spring (average 21.2°C) and summer temperatures (average 27.1°C) to investigate the influence of dietary energy on broiler performance, carcase yield and nutrient composition of breast meat. 2. Birds were fed on a low energy diet of 12.12 MJ ME/kg, a medium energy diet of 12.96 MJ ME/kg and a high energy diet of 13.79 MJ ME/kg with 2 protein concentrations per energy treatment, 230 and 200 g/kg, from 0 to 3 and 3 to 7 weeks of age, respectively. 3. Summer rearing resulted in a decrease in body weight, body weight gain, carcase weight and carcase part yields of birds. 4. Increasing dietary energy from 12.12 to 13.79 MJ ME/kg increased body weight at 3 and 7 weeks, body weight gains from 0 to 3 and 3 to 7 weeks, carcase weights and relative abdominal fat weights of birds in a linear manner. There was no effect of dietary energy on the nutrient composition of breast meat. 5. It was concluded that there was no differences in dietary energy requirements of heterozygous naked neck birds when grown under natural optimum (21.2°C) and summer temperatures (27.1°C).  相似文献   

12.
Studies have been carried out to ascertain the effects of ammonia on the performance of White Leghorn hens housed in various environments of defined temperature and humidity. At 18° C. and 67 per cent relative humidity, the use of atmospheres containing 105 p.p.m. of ammonia by volume, significantly reduced egg production after 10 weeks’ exposure. No effects were observed on egg quality. However voluntary food intake was reduced in ammoniated atmospheres and live‐weight gain was lower. No recovery in production occurred when the treated groups were maintained for a further 12 weeks in an atmosphere free of ammonia.

When White Leghorn hens were housed at an environmental temperature of 28° C., body weight declined. The decrease in live‐weight was greatest at the high ammonia concentration of 102 p.p.m., and was significant after only 1 week's exposure to ammonia. Food intake of the controls was approximately 25 per cent lower at 28° C. than at 18° C., whilst 100 p.p.m. of ammonia further reduced food intake by more than 10 per cent. In one experiment at 28° C., egg production was significantly reduced after 7 weeks' exposure to ammonia.

In a subsequent trial, a high protein, vitamin and mineral diet prevented the onset of any deleterious effects of ammonia on egg production, even though food consumption fell to 75 g./bird/day at 29° C., 43 per cent relative humidity and 104 p.p.m. of ammonia. When a diet low in energy level was fed to hens subjected to high concentrations of ammonia, their voluntary food intake did not increase, and their production deteriorated rapidly.  相似文献   


13.
Using a model to generate experimental groups with different manifestations of post‐partum (p.p.) fat mobilization and ketogenesis, the effects of a dietary and a medical intervention on biochemical and haematological parameters, antibody titre, leucocytes subsets and function of transition cows were examined. In total, 60 German Holstein cows were allocated 6 weeks antepartum (a.p.) to 3 high‐body condition score (BCS) groups (BCS 3.95) and 1 low‐BCS group (LC, BCS 2.77). High‐BCS cows received a monensin controlled‐release capsule (HC/MO) or a blend of essential oils (HC/EO) or formed a control group (HC). Parameters were evaluated in 3 periods (day (d) ?42 until calving, 1 until 14 days in milk (DIM), 15 until 56 DIM). Over the course of trial, various parameters were influenced by period with greatest variability next to calving. White blood cell count was higher in the HC (8.42 × 103/μl) and HC/EO (8.38 × 103/μl) groups than in the HC/MO group (6.81 × 103/μl) considering the whole trial. Supplementation of monensin decreased aspartate aminotransferase in comparison with the HC group similar to LC treatment. Bilirubin concentration was nearly doubled in all high‐BCS cows in period 2. In period 3, essential oils increased γ‐glutamyltransferase (80.4 Units/l) in comparison with all other groups and glutamine dehydrogenase (61 Units/l) in comparison with the LC (19 Units/l) and the HC/MO group (18 Units/l). Results suggest that parameters were generally characterized by a high variability around calving. Based on biochemical characteristics, it appeared that the HC cows seemed to have compromised hepatocyte integrity when compared to the LC cows. From the immune parameters investigated, the BVDV antibody response was more pronounced in HC/MO compared to HC/EO.  相似文献   

14.
Sex determination in C. caretta is, under natural conditions, dependent on incubation temperature. In general, below 27°C all hatchlings are male while above 29,3°C 80% or more are females. The sex ratios of the nests were also dependent on the time of season which is directly related to temperature. Metabolic heating of the nest was evident only towards the end of the critical period i.e. post-sexual differentiation. There was no correlation between sex ratios and the physical characteristics of the beach. The implications of temperature sex determination on the limitation of geographical populations are also discussed.  相似文献   

15.
ObjectivesTo investigate the character of immobilization given by alfaxalone in juvenile crocodiles at optimal and at suboptimal temperatures.Study designProspective, randomized partial crossover study.AnimalsTwenty captive male estuarine (weight 0.6–2.5 kg) and five captive male freshwater crocodiles (weight 0.2–0.6 kg).MethodsCrocodiles were acclimatized for 24 hours at one of the following environmental temperatures; 32 °C, 27 °C, 22 °C or 17 °C, then received 3 mg kg?1 intravenous (IV) alfaxalone into the dorsal occipital venous sinus. Duration and quality of immobilization was assessed and heart rate (HR) measured. On a separate occasion each crocodile was immobilized at one other environmental temperature.ResultsAlfaxalone, 3 mg kg?1 IV, produced immobilization for 55 (range 15–100 minutes in estuarine, and 20 (range 20–25) minutes in freshwater crocodiles at 32 °C. There was no significant difference overall in immobilization times between temperatures, other than that, in estuarine crocodiles, duration was shorter at 32 °C than 22 °C. The character of immobilization was unpredictable, with animals recovering without warning, or having extended recoveries requiring assisted ventilation. Assisted ventilation was necessary mainly at the lower temperatures. Median HR in all temperature treatments decreased within 5 minutes post–injection, but the change in HR over the duration of immobilization was affected by the temperature, with a progressively smaller range of fall as temperature decreased. At 17 °C, two estuarine crocodiles appeared to re–immobilize after initial recovery, became severely bradycardiac and required ventilation and re–warming.Conclusions and clinical relevanceAlfaxalone IV in small captive estuarine and freshwater crocodiles provides adequate induction of immobilization at various temperatures. However, the unpredictable results following induction mean it is unsuitable for field use and should be restricted to environments where intubation and ventilation are available, where animals can be warmed to optimal temperature, and where access to immersion in water can be restricted for 24 hours.  相似文献   

16.
1. The effects of exogenous corticosterone on plasma corticosterone concentrations, body weight, food intake, the percentage of birds that laid an egg each day and egg weight were measured in laying Japanese quail. Data were collected from birds in the week before corticosterone treatment began, during a 21-d treatment period, and in the 22 d after treatment ended.

2. Groups of quail were treated with corticosterone at three different concentrations in their drinking water. Corticosterone intakes were calculated for each bird and birds were then assigned to 4 intake groups. The groups were 0 (control group), 0·31–0·60, 0·61–0·90, 0·91–1·50 or >1·51 mg corticosterone/bird/d.

3. Plasma corticosterone concentrations in the 4 intake groups increased from around 1 ng/ml on the day before corticosterone treatment began to maximum mean concentrations of 13–18 ng/ml on day 14 of treatment. Mean corticosterone concentrations did not change between day 14 of treatment and the day after treatment ended, and had decreased in only one of 4 intake groups one week later.

4. Mean body weight in the highest intake group remained significantly lower than in controls 22 d after corticosterone treatment ended. Whilst there was no clear effect of corticosterone on food intake during treatment, mean food intake in the three highest corticosterone intake groups was significantly lower than in controls in the week after treatment ended. The percentage of birds that laid an egg each day and egg weight were both decreased by corticosterone, and the percentage of birds that laid an egg each day remained significantly lower in the highest corticosterone intake group compared with controls in the third week after treatment ended.

5. It is suggested that elevated plasma corticosterone concentrations in quail after treatment ended were maintained by a hyperactive hypothalamo–pituitary–adrenal axis for at least one week. Although none of the negative effects of corticosterone were evident in the group of quail with the lowest corticosterone intakes, the findings of the present study show that corticosterone treatment can affect birds for up to several weeks after corticosterone intake ends.  相似文献   


17.
Pelibuey and Suffolk sheep were compared as to their capacity to regulate body temperature under environmental hyperthermia by measuring their differences in cellular response to heat stress (HS). In a first experiment, seven Pelibuey and seven Suffolk ewes were kept in a climatic chamber for 6 h daily during 10 days (temperatures within the 18 to 39.5 °C range). As chamber temperature rose, sheep rectal temperature increased in both groups, but to a lesser extent in Pelibuey (0.3 °C) than in Suffolk sheep (0.7 °C) (P?<?0.05). In a second experiment, cellular viability was assessed using cultured blood mononuclear cells from 15 Pelibuey and 15 Suffolk sheep. They were incubated at 37 °C for 24 h (control) or 43 °C for 6 h followed by 18 h at 37 °C (HS). In a third experiment, another blood mononuclear cells culture from eight Pelibuey and eight Suffolk sheep was kept at 37 °C for 15 h; these were subsequently cultured for 6 h at 37 °C (controls) or 43 °C (HS). Next, HSP-70 concentration was determined. HS reduced the percentage of viable cells to a greater extent in Suffolk [37 °C (73.7 %) vs. 43 °C (61.9 %); P?<?0.05] than in Pelibuey sheep [37 °C (74.9 %) vs. 43 °C (66.7 %); P?>?0.05]. HS significantly increased HSP-70 average concentrations for both breeds at 43 °C. A significant effect was observed for the breed by temperature interaction (P?<?0.05) caused by a greater difference between Pelibuey and Suffolk at 43 °C (2.85 vs. 0.53 ng/mL, respectively; P?<?0.05) than at 37 °C (0.05 vs. 0.03 ng/mL, respectively; P?>?0.05). In conclusion, Pelibuey sheep show more effective body temperature regulation under conditions of environmental hyperthermia. Also, cell viability after HS was higher in Pelibuey than in Suffolk, an effect that could be mediated by an HSP-70-related mechanism.  相似文献   

18.
Chicks hatched from eggs incubated at two temperatures (36.8 °C, 37.8 °C) but similar humidities (30 mmHg during the first 18 d and 40 mmHg thereafter) were reared for 12 weeks in groups of six at 22 °C and in a relative humidity of 45 to 55%.

The lower incubation temperature resulted in a longer incubation period. Female embryos utilised the energy of the egg better than males.

A possible difference in the relationship between the post‐hatching development of males and females and pre‐hatching environmental conditions was indicated by a higher viability at 14 d and a higher body weight after 12 weeks of cocks incubated at 36.8 °C. There were significant effects of sex on food conversion efficiency. Results suggest that pre‐hatching temperatures may influence post‐hatching energy utilisation.  相似文献   


19.
Abstract

AIMS: To assess the effect of two temperatures (ambient temperature and 4°C), three preservation methods (no preservative, yoghurt and potassium sorbate), and two periods of storage (3 and 7 days) on Brix and total bacterial and coliform counts of colostrum collected from New Zealand dairy farms.

METHODS: One litre of colostrum destined to be fed to newborn calves was collected from 55 New Zealand dairy farms in the spring of 2015. Six aliquots of 150 mL were obtained from each colostrum sample, with two aliquots left untreated, two treated with potassium sorbate and two with yoghurt, and one of each pair of aliquots stored at ambient temperature and the other at 4°C. All samples were tested for Brix, total bacterial counts and coliform counts before treatment (Day 0), and after 3 and 7 days of storage. The effect of preservation method and storage temperature on the change in Brix, bacterial and coliform counts after 3 or 7 days of storage was analysed using multivariable random effects models.

RESULTS: For all outcome variables there was a temperature by preservation interaction. For aliquots preserved with potassium sorbate, changes in Brix and bacterial counts did not differ between aliquots stored at ambient temperature or 4°C, but for aliquots preserved with yoghurt or no preservative the decrease in Brix and increase in bacterial counts was greater for aliquots stored at ambient temperature than 4°C (p<0.001). For aliquots preserved with potassium sorbate, coliform counts decreased at both temperatures, but for aliquots preserved with yoghurt or no preservative coliform counts increased for aliquots stored at 4°C, but generally decreased at ambient temperatures (p<0.001). There was also an interaction between duration of storage and temperature for bacterial counts (p<0.001). The difference in the increase in bacterial counts between aliquots stored at 4°C and ambient temperature after 3 days was greater than between aliquots stored at 4°C and ambient temperature after 7 days.

CONCLUSIONS AND CLINICAL RELEVANCE: Use of potassium sorbate to preserve colostrum for 3 or 7 days resulted in little or no reduction in Brix and a lower increase in total bacterial counts than colostrum stored without preservative or with yoghurt added. Colostrum quality was not affected by storage temperature for samples preserved with potassium sorbate, but storage at 4°C resulted in better quality colostrum than storage at ambient temperatures for colostrum with no preservative or yoghurt added.  相似文献   

20.
Further field observations and laboratory studies on the biology and ecology of Damalinia bovis and Linognathus vituli, the two most common cattle louse species in New Zealand, are described.

The life cycle of D. bovis was completed in 27–32 days while L. vituli took 26–31 days. The winter distribution of both species on individual animals was similar with the heaviest concentrations on the cranial half of the body. The effect of the haircoat composition on distribution was examined; correlations between louse counts and hair diameters, colour composition of hair populations, hair and debris density, and sample sites were estimated for both species. The only significant correlation of D. bovis counts was with sample site. Findings were similar for L. vituli except that there was also a significant correlation between louse numbers and weight of hair and skin debris. The importance of self-grooming is discussed in relation to louse distribution.

Reasons for seasonal population fluctuations are considered including coat loss and temperature variations. It was shown experimentally that temperatures 5°C either side of the optimum 35°C prevented D. bovis eggs from hatching.  相似文献   

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