The prophylactic effect of vitamin C supplementation

Avian Pathology

ISSN: 0307-9457 (Print) 1465-3338 (Online) Journal homepage: http://www.tandfonline.com/loi/cavp20

The prophylactic effect of vitamin C supplementation on broiler ascites incidence and plasma thyroid hormone concentration M. Hassanzadeh Ladmakhi , Nadine Buys , Erna Dewil , G. Rahimi & E. Decuypere To cite this article: M. Hassanzadeh Ladmakhi , Nadine Buys , Erna Dewil , G. Rahimi & E. Decuypere (1997) The prophylactic effect of vitamin C supplementation on broiler ascites incidence and plasma thyroid hormone concentration, Avian Pathology, 26:1, 33-44, DOI: 10.1080/03079459708419191 To link to this article: http://dx.doi.org/10.1080/03079459708419191

Published online: 12 Nov 2007.

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Date: 28 January 2016, At: 10:50

Avian Pathology (1997) 26, 33-44

The prophylactic effect of vitamin C supplementation on broiler ascites incidence and plasma thyroid hormone concentration M. HASSANZADEH LADMAKHI, NADINE BUYS, ERNA DEWIL, G. RAHIMI & E. DECUYPERE

Downloaded by [81.19.129.122] at 10:50 28 January 2016

Laboratory for Physiology and Immunology of Domestic Animals, K. U. Leuven, Kardinaal Mercierlaan 92, B-3001 Heverlee, Belgium

SUMMARY In a two-factorial experiment, 420 1-day-old male commercial broiler chickens were randomly divided and fed a basal diet with or without vitamin C (500 parts/106). Half of the birds within each group receiving the same kind of feed were fed a T 3 supplemented diet from day 1, in order to increase the ascites incidence. Weekly body weight and feed intake were measured. Venous blood samples were taken from 10 birds per group weekly from day 14 on, for haematocrit measurements, blood gas analysis, measurement of thyroid hormones and lactate/pyruvate ratios. Ascites mortality was recorded daily. Dietary T 3 significantly increased ascites mortality. Adding vitamin C to the feed significantly reduced ascites mortality while it had no effect on performance parameters. Plasma thyroid hormone levels were significantly reduced by dietary vitamin C administration, but neither haematocrit nor blood gas levels were influenced.

INTRODUCTION The incidence of high altitude disease or ascites resulting from pulmonary hypertension (PH), and, consequently, cardiac hypertrophy, heart failure and oedema, in broiler chickens kept at altitudes of approximately 3000 m, has been described by Sillau et al. (1980). More recently, similar signs and mortality rates were reported in broilers reared at lower altitudes of 1000 to 2000 m (Van Blerck, 1985) and at altitudes down to sea level (Albers & Frankenhuis, 1990). Ascites is a complex syndrome for which the major inducing factor is thought to be a lack of oxygen. Decreased oxygen tensions and/or increased oxygen requirements can create hypoxic conditions at the tissue level and this may Received 27 November 1995; Accepted 15 May 1996. Correspondence: Professor E. Decuypere, Department of Animal Science, Kard. Mercierlaan 92, B-3001 Heverlee, Belgium. 0307-9457/97/010033-12 © 1997 Houghton Trust Ltd


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M. HASSANZADEH ETAL.

seriously influence PH. Many questions remain to be answered concerning the factors leading to hypoxia and the pathophysiological effects of hypoxia on the chicken. Histopathology studies by Maxwell et al. (1986, 1990) indicated that a large number of inflammatory cells were observed in numerous tissues of ascitic birds and in the hearts of experimentally-induced hypoxic birds. Also, Enkvetchakul et al. (1993) pointed out that activated white blood cells can generate a variety of reactive oxidants into surrounding tissues, which may, in turn, alter tissue antioxidant status. In addition, dietary vitamin C has been reported to improve resistance to a variety of Stressors, including toxic salt and hypoxia (Al-Taweil & Kassab, 1990; Agudelo, 1983). The primary cause of ascites in broilers is hypoxia-induced PH, but the exact biochemical mechanisms responsible for producing the disease have not been identified. There are several reports (Enkvetchakul et al, 1993; Al-Taweil & Kassab, 1990; Agudelo, 1983) suggesting that free radical-mediated mechanisms may be involved in the aetiology of PH syndrome (PHS). Bottje & Wideman (1995) reported that the production of free radicals is contributed to by systemic hypoxia, inflammation and thyroid hormones. The potential of oxygen-derived free radicals to cause cytotoxic damage was also proposed by Maxwell et al. (1994). They suggested that, together with granulocytes, mitochondria in ascitic and hypoxic birds may be a source of oxygen-free radicals in injured myocardial cells and that these components may play an important role in the synthesis of tissue damage in broilers. They also argued that oxygen-free radicals cause tissue damage through lipid peroxidation of cell membranes which leads to increased membrane permeability. These reviews support the idea that oxygen-derived free radicals are generated, rather than ischaemia in hypoxic birds. Because oxygen-derived free radicals play an important role in the genesis of tissue damage during inflammatory reactions and ischaemia in humans (Halliwell & Gutteridge, 1990), it is reasonable to hypothesise that the development of ascites may be due in part to free radical generation from mitochondria of cardiomyocytes of ascitic and hypoxic birds, with subsequent depletion of tissue antioxidants (M. H. Maxwell, personal communication). Earlier studies showed that dietary vitamin C can be effective in reducing mortality in laying hens (Ahmad et al., 1967; Thornton, 1962) and broilers (Njoku, 1986) reared under environmental stress. Pardue & Thaxton (1986) concluded that, although vitamin C is not an essential nutrient for chickens maintained in optimal conditions, it may become an essential vitamin for birds under environmentally, pathologically or nutritionally stressful conditions. This experiment was conducted to investigate the effect of vitamin C supplementation on ascites mortality, performance, and some metabolic and hormonal parameters of commercial broilers reared under a relatively low ambient temperature. Since dietary T 3 increases ascites mortality (Decuypere et al, 1994), the administration of 1.5 parts/106 of T 3 in the feed could increase the difference in ascites mortality between birds fed a vitamin C supplemented diet and those receiving a control diet.

PROPHYLACTIC EFFECT OF VITAMIN C ON ASCITES

35


MATERIALS AND METHODS A total of 420 male broiler chickens of a commercial strain (Ross) were randomly divided and fed a basal diet (3500 kcal ME and 24% crude protein) with or without 1.5 parts/106 T 3 (T2627, Sigma, St Louis, MO, USA) from day 1 and with or without 500 parts/106 vitamin C (A7506, Sigma, St Louis, MO, USA) added to the diet in a 2-factorial experiment. Each group was composed of seven replicates of 15 birds per replicate. They were subjected to a step down temperature programme of 1°C per 2 days, starting from 32°C (day 1) down to 16°C (day 33). All birds were then maintained at this ambient temperature until 6 weeks of age. The lighting programme was 23 h light and 1 h dark. Weekly body weight and feed intake were measured per replicate. From 10 birds per group venous blood samples were taken weekly from day 14 on. Blood was collected in heparinized capillaries for haematocrit and blood gas measurements (IL 1306 Blood gas analyser Lexington, MA, USA) and in heparinized tubes on ice for the separation of plasma. Haematocrit was measured immediately while plasma was stored at — 20°C until further analysis. Plasma was analysed for thyroid hormones (T 3 and T4) as described earlier (Decuypere et al, 1994). Plasma lactate and pyruvate concentrations were measured using, respectively, Sigma kits 826 and 726 (Sigma, St Louis, MO, USA). Both assays were based on the spectrophotometric measurement (X = 340 nm) of NADH produced by lactate dehydrogenase. Throughout the study mortality was recorded daily. At the termination of the experiment, five chickens from each group were randomly selected and slaughtered. These birds and the broilers which died during the experimental period were examined for lesions of heart failure syndrome and ascites. The heart was removed and the atria, major vessels and fat were trimmed off. The right ventricle (RV) was carefully cut away from the left ventricle and septum. The right ventricle was weighed, the left ventricle and septum were added, and the total ventricle (TV) was weighed. Birds having a RV/TV ratio of over 0.299 were classified as suffering from right ventricular failure (Julian, 1987). Statistical analysis was performed using the 'LSMeans procedure' (SAS, 1986).

RESULTS Ascites Mortality and RV/TV Ratio The number of broilers that developed right ventricular hypertrophy (RVH) and ascites in the different age and treatment groups and the ratios of RV/TV are shown in Table 1. During the experiment 41 (9.8%) of the 420 birds died. All of them showed RVH and ascites up to 6 weeks of age. Dietary T 3 markedly increased ascites mortality (mean RV/TV ratio = 0.37). There was no difference in mean RV/TV ratio of surviving birds which were killed randomly at 43 days of age. Ascitic chickens showed moderate to severe ascites with clots of fibrin floating in the fluid and covering the liver. The heart was flaccid due to right

36

M. HASSANZADEH ETAL.

Table 1. Ascites mortality and corresponding R V/TVratio in commercial broilers that were reared at low environmental temperature (32°C on day 1 to 16°C on day 33) and given a control or a T3 supplemented diet (1.5 parts/106) with or without 500 parts/106 vitamin C


Ascites mortality in week Dietary supplement

3

4

5

6

Total

RV/TV

None Vitamin C T3 T3 and vitamin C

2 0 3 1

3 0 8 3

1 0 10 2

0 0 5 3

6 0 26 9

0.34 0 0.33 0.37

Total

6

14

13

8

41

0.37

ventricular hypertrophy and dilation. The lungs and kidneys were congested, and sometimes haemorrhagic. The liver was swollen or shrunken. Ascites mortality occurred from 3 weeks of age onwards, and the rate increased considerably between weeks 4 and 6. In the dietary T 3 groups, 26 birds which had been fed T 3 only, died due to RVF induced ascites, while the mortality of ascites was clearly reduced (65%) by the effect of 500 parts/106 vitamin C supplementation in the T 3 treatment group. A similar significant reduction of ascites mortality due to vitamin C supplementation was observed in broilers which were fed control food (without T 3 ). In the control diet group, six birds showed RVH while there were no cases of ascites in the chickens which had received vitamin C in control diets. Growth Maximal absolute growth values were observed at 4 and 5 weeks of age (Table 2). Beside the obvious effect of age, adding T 3 to the diet had a significant growth depressant effect (P< 0.0001) in all conditions while vitamin C did not alter the growth.

Feed intake Feed intake increased as a function of age and dietary T 3 treatment significantly decreased feed intake ( P < 0.001). There was no significant influence of vitamin C supplementation on feed intake (Table 2).

Food conversion The food conversion rate (FCR) increased during the growing period (P< 0.0001). Dietary T 3 tended to increase FCR, but this effect was only significant in week 4. Dietary vitamin C did not alter FCR (Table 2).

37

PROPHYLACTIC EFFECT OF VITAMIN C ON ASCITES

Table 2. Mean body weight gain (g/chicken/week), feed intake (g/chicken/week) and feed conversion ratio in commercial broilers that were reared at low environmental temperature (32°C on day 1 to 16°C on day 33) and given a control or a T¡ supplemented diet (1.5 parts/106) with or without 500 parts/106 vitamin C Week Dietary supplement Body weight gain None Vitamin C T3 T3 and vitamin C


Feed intake

None Vitamin C T3 T3 and vitamin C

1

2

97" a

104 88 e 88 e

3

4

5

6

Total

214a 223 a 179b 166"

313a 319a 23 l b 210b

462a 460a 362b 334"

448ab 476a 358e 380be

404 387 388 405

1990a 1994a 1679b 1623b

284a 292a 244b 242b

433 b 503a 403 e 336e

736a 745a 527b 595b

969a 879ab 780b 836ab

1108 1030 1020 1056

3559a 3451 a 2933" 3105b

1.33 1.32 1.38 1.47

1.39b 1.58a 1.60a 1.64a

1.76 1.62 1.67 1.59

2.25 1.89 2.36 2.08

3.02 2.77 2.78 2.52

1.89 1.81 1.82 1.94

FCR

None Vitamin C T3 T3 and vitamin C a>blC

Means with the same indices within a column are not significantly different for P< 0.05.

Haematocrit At 4 weeks of age dietary T 3 significantly increased haematocrit in birds receiving a diet without vitamin C. Although no significant effect of feed or treatment could be found, the overall haematocrit values changed during the experimental period and a significant interaction between age and treatment was observed (Table 3).

Thyroid hormones In control fed birds, plasma T 3 concentrations decreased and T 4 increased with increasing age from week 3 on ( P < 0.001). Dietary T 3 supplementation significantly increased plasma T 3 levels and decreased T 4 levels ( P < 0.001). Vitamin C decreased plasma T 3 concentrations in birds fed a T 3 supplemented diet ( P < 0.05), but not in control birds at 5 and 6 weeks of age (diet X treatment interaction P< 0.001). At 4 weeks of age, plasma T 4 levels were higher in birds fed a vitamin C supplemented diet compared to those fed a control diet (P