ARTICLE ORIGINAL

Effects of boron supplementation on performance and some serum biochemical parameters in laying hens* ° V. KURTOGLU, °° F. KURTOGLU, ° B. COSKUN, ° E. SEKER, ° T. BALEVI and °°° I.S. ÇETINGUL ° Departments of Animal Nutrition and Nutritional Diseases °° Biochemistry, Faculty of Veterinary Medicine, University of Selçuk, Konya, Turkey °°° Department of Animal Nutritional Diseases, University of Afyon Kocatepe, Faculty of Veterinary Medicine, Afyon, Turkey Correspondence to : Dr. Varol Kurtoglu, Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, University of Selçuk, 42075 Konya, Turkey E-mail : [email protected]

* This study is a research project funded by Research Foundation of Selçuk University (SÜAF) Project Number : SÜAF 99/009

SUMMARY

RÉSUMÉ

In this study, the effects of dietary boron (0,50, 100, 150, 200 and 250 parts per million ; ppm) on performance such as feed consumption, feed conversion ratio, egg production, body weight, egg weight, specific gravity, damaged egg ratio, and some biochemical characters (Ca, P and Mg) in 40 week old laying hens for 120 days were investigated. Boron provided significant improvements on serum Ca levels and damaged egg ratio. There was no significant difference between the controls and the boron supplemented groups in the feed consumption, feed conversion ratio, egg production, body weight, egg weight and specific gravity.

Effets de la supplémentation de l’alimentation en bore sur les performances et sur quelques paramètres biochimiques du sérum chez les poules pondeuses. Par V. KURTOGLU, F. KURTOGLU, B. COSKUN, E. SEKER, T. BALEVI et I.S. ÇETINGÜL.

KEY-WORDS : boron - performance - blood parameters laying hen.

MOTS-CLÉS : bore - performance - paramètres de sang poule pondeuse.

Introduction

Recently it has been suggested that B has a possible role in animal and human nutrition. Several studies have indicated that B is an important mineral for body weight, feed consumption, reduced mortality rate, normal cartilage and bone formation in broilers ; egg production, egg weight, specific gravity in laying hens. QIN and KLANDORF [18] studied the effects of dietary B on egg production, egg shell quality and Ca metabolism in broiler breeder hens. Results from 3 experiments indicated that B decreased egg production in experiment 1, but not in the experiments 2 and 3. WILSON and RUSZLER [29] used a dietary supplement of either 0, 100, 200, or 400 mg kg-1 of B for 12 weeks. Strength characteristics were not affected by increasing concentrations of B but egg production and food consumption were decreased by B concentration of 400 mg kg-1. Body weight was also decreased at 400 mg kg-1 of B. WILSON [27] reported that shear breaking strength increased with bone ash content for

Boron (B), is a dark brown, nonmetal element that is found in nature as borax, colemanite, boronatrocalcite, and boracite. It acts as a Lewis acid, accepting hydroxyl ions, and thus leaving an excess of protons. Boron complexes with organic compounds containing hydroxyl groups, and those with more than two hydroxyl react more strongly. Thus, B is capable of interacting with substances of biological interest, including polysaccharides, pyridoxine, riboflavin, dehydroascorbic acid, and pyridine [10]. The average B content [(part per million ; (ppm)] in dry weight) in different food groups is as follows ; cereals 0.92, meat 0.16, fish 0.36 ; dairy products, 1.1 and vegetable foods 13 [15]. Boron is distributed throughout the tissues and organs of animals at concentrations mostly between 0.05 to 0.6 ppm fresh weight and several times of these levels in the bones [26]. Revue Méd. Vét., 2002, 153, 12, 823-828

Dans cette étude, les effets du bore dans l’alimentation (0,50, 100, 150, 200 et 250 parties par million : ppm) sur les performances telles que la consommation d’aliment, le ratio de conversion de l’aliment, la production des œufs, le poids corporel des volailles, le poids des œufs, leur densité, le taux d’œufs endommagés et quelques paramètres biochimiques (Ca, P et Mg) ont été étudiés chez les poules pondeuses âgées de 40 semaines pendant 120 jours. Le bore a provoqué des améliorations significatives sur le taux sérique de Ca et sur le nombre d’œufs endommagés. Par contre, il n’a été noté aucune différence significative entre le groupe témoin et les groupes traités pour tous les autres critères étudiés.

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laying hens. The other research [31] results support that the 200 mg kg-1 of dietary B supplemented at peak egg production will decrease bone brittleness. Boron has been shown to have a beneficial effect on mineral metabolism of some species. Therefore a method to improve mineral balance in order to increase the bone strength of laying hens could benefit the poultry industry [29]. Boron has been examined as a possible nutritional factor in calcium (Ca) metabolism and utilisation, and thus as a factor in the development and maintenance of normal bone [15]. Bone-breaking strength and bone ash are often used as criteria for assessing the values of various dietary supplements, cage designs and animal densities for preventing bone breakage. For this reason, the National Research Council [11] suggested that the trace mineral supplements to chemically defined diets should contain at least 2 ppm B, although the B requirement for the different categories of poultry has not been determined [5, 16, 21]. HUNT et al., [7] in a series of experiments with day-old chicks fed for 30 days, indicated a relationship between B and other nutrients (Ca, Mg, and vitamin D3). Signs of B deficiency may be related to the level of vitamin D3, Mg and possibly other nutrients in the diet. HUNT and NIELSEN [6] and KURTOGLU et al., [9] supplemented various levels of B and either adequate or inadequate amounts of vitamin D3. They found a positive relationship between B and vitamin D3. Indeed, comparison of the findings on growth from the boron-calcium (B-Ca) and boron-magnesium (B-Mg) studies suggested that the relationship between B-Mg was stronger than that between Ca or P and B. HUNT et al., [8] reported that B acts by at least three different mechanisms. First, B compensates for perturbations in energy substrate utilisation induced by vitamin D3 deficiency. Second, B enhances macro mineral content in normal bone. Third, dietary B independently of vitamin D3, enhances some indices of growth cartilage formation. NIELSEN et al., [13] indicated, this function of B related to its parathormone regulating action. Therefore B is needed by the parathyroid and has been shown to prevent loss of Ca and bone demineralisation especially in postmenopausal women. The purpose of this study was to evaluate the effects of various levels of B supplementation on performance and some biochemical parameters in 40 weeks of age laying hens.

KURTOGLU (V.) AND COLLABORATORS

10 layers making a subgroup) and these animals were housed in eight different cages. The subgroups were distributed randomly among the different compartments of the cage system. Each subgroup consisted of 2 cages, each of which was 55x45x40 cm in dimensions. 5 hens/cage (55x45x40 cm) were placed. The distribution resulted in 96 cages and 480 laying hens. Experimental period was 120 days.

DIET AND BORIC ACID In the trial, chickens received basal diet (as shown Table I). But B were weighed individually and supplemented to diets in homogenous form. As the B source, orthoboric acid was used since it is a common inorganic form of B of high purity (99.995 per cent) and well absorbed from the gastrointestinal tract [17]. In the pre-experimental period B supplementation was not made into diets. Chemical composition of the diet is shown in Table II.

HEN-DAY EGG PRODUCTION The hen-day egg production was recorded for two weeks to check for similar pre-experiments values for treatments. The hen-day egg production were then recorded daily at the same time and calculated as total number of eggs collected divided by total number of live hens per day in each group. The collected eggs were classified as «normal» or «damaged ; the latter included the following : broken eggs (an egg with broken shell and destroyed membrane), cracked eggs (an egg with broken shell but intact membrane), the shell-less eggs (an egg without shell but with intact membrane).

FOOD CONSUMPTION AND FOOD CONVERSION RATIO Feed and water were supplied for ad libitum throughout the 120-day experimental period. Food consumption (FC) and food conversion ratio (FCR) were determined at 14 day intervals.

Materials and methods ANIMALS A total of 480 40-week-old Hysex-Brown layer hybrids, which were obtained from University of Selçuk, Faculty of Veterinary Medicine, Animal Husbandry and Research Unit, were used in this study.

EXPERIMENTAL DESIGN The animals were randomly divided into six groups. To limit the position differences, these groups were divided into eight subgroups consisting of 10 chicks each (8 replicates of

1

Per 2.5 kg of vitamin premix contains 3.6 mg vitamin A, 0.05 mg vitamin D3, 30 mg vitamin E, 3 mg vitamin K3, 3 mg vitamin B1, 6 mg vitamin B2, 5 mg vitamin B6, 0.015 mg vitamin B12, 25 mg niacin, 0.04 mg biotin, 8 mg karotenoid, 1 mg folic acid, 300 mg choline chloride, 50 mg vitamin C. 2 Per kg of mineral premix contains 80 mg Mn, 35 mg Fe, 50 mg Zn, 5 mg Cu, 2 mg I, 0.4 mg Co, 0.15 mg Se. TABLE I. — Composition of the diets.

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EFFECTS OF BORON SUPPLEMENTATION ON PERFORMANCE

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Results B additions (0, 50, 100, 150, 200, 250 mg kg-1) have no significantly effect on egg production, egg weight and specific gravity (Table III, IV and VI). On period of 60-90 d the damaged egg ratio were significantly lower in 150 and 250 mg kg-1 B supplemented groups than control groups (Table V, P < 0.05). Feed consumption and body weight were not influenced by any concentrations of B (Table VII and IX). Serum Ca levels increased, especially in group 250 mg kg-1 B significantly (P < 0.05). There was no significant difference between control and B supplemented groups in serum Mg and P values.

* Obtained by calculation. TABLE II. — Analysis of diets

EGG WEIGHT AND SPECIFIC GRAVITY Egg weight and specific gravity were determined monthly using the methods described by HAMILTON [3] and HEMPE et al., [4].

NUTRIENT COMPOSITION OF EXPERIMENTAL DIETS Crude protein, dry matter, ash, crude fibre, lipid content, Ca and P values of the experimental diet were determined by chemical analysis [1].

BIOCHEMICAL MEASUREMENTS Serum Ca, Mg, and P levels were measured with Spectrophotometer (Shimadzu, UV 2100) using commercial kits (Pointe Scientific Inc., Michigan, USA). Blood samples were taken from 12 chicks in each group by cardiac puncture on the 120th day.

STATISTICAL ANALYSIS One-way analyses of variance of egg yields, egg weights, FC, FCR and damaged egg ratios and biochemical characters (Ca, P and Mg) were conducted. Any significant differences were further analysed by Duncan’s multiple range test [22].

Discussion This study was carried out to evaluate the effects of various levels of B supplementation on egg production, egg weight, specific gravity, FC, FCR, BW, damaged egg ratio and some biochemical parameters in laying hens. In agreement with ROSSI et al., [20] 0-250 mg kg-1 dietary B has no effect on egg production (Table III). Similarly, WILSON and RUSZLER [28, 29, 31] suggested that 0-200 mg kg-1 B supplementation had no effect on egg production. These results contrast with these of QIN and KLANDORF [18] where B supplementation at 100 mg kg-1 caused a significant decrease in egg production in one of two experiments. Also, egg production, were suppressed at a dietary B concentration of 400 mg kg-1 [29, 31]. WILSON and RUSZLER [29] found that 400 mg kg-1 dietary B concentration had no effect on egg weight in 81 week aged birds, but in the other study [31] it was found that the egg weight decreased at 400 mg kg-1 B in 28-72 week aged laying hens. In our study egg weight were not negatively affected by supplementation of 0-250 mg kg-1 B. Egg specific gravity, a measure of egg shell quality was not affected by any of the B concentrations used in this study. In some other research, have been reported that B supplementation to 400 mg kg-1 did not cause negative effect on egg specific gravity in broiler breeder hens [21] and laying hens [18, 29]. Boron supplementation significantly affected the damaged egg ratio (%) on period of 60-90 d, whilst these ratios for this period of the study in the control and 150 and 250 mg kg-1 B supplemented groups were 2.36,

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. * days of experimental period TABLE III. — Effect of different levels of dietary boron on egg production in laying hens fed for 120 days. Revue Méd. Vét., 2002, 153, 12, 823-828

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KURTOGLU (V.) AND COLLABORATORS

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. * days TABLE IV.— Effect of different levels of dietary boron on egg weight in laying hens fed for 120 days.

* Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. a,b Means within columns with no common superscripts are significantly different (P < 0.05), according to Duncan’s multiple range test * days of experimental period TABLE V. — Effect of different levels of dietary boron on damaged egg in laying hens fed for 120 days.

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. * days TABLE VI. — Effect of different levels of dietary boron on egg specific gravity in laying hens fed for 120 days.

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. * days of experimental period TABLE VII. — Effect of different levels of dietary boron on feed consumption in laying hens fed for 120 days.

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EFFECTS OF BORON SUPPLEMENTATION ON PERFORMANCE

0.98 and 0.70 respectively (P < 0.05) (Table V). In the whole period of this study (1-120 d), despite no significant differences, decreases in damaged egg ratios were found in all groups when compared with controls. Obtaining the low damaged egg ratios from the experiments used with laying hens has profitable effect on poultry industry. It is suggested that poor shell quality in aged laying hens is associated, with a loss in the ability to absorb minerals [25]. According to QIN and KLANDORF [18] B can improve mineral balance. It was reported that B supplementation to 200 mg kg-1 did not affect FC in laying hens [29, 31] and white leghorn chicks [30]. Also in our study, B supplementation to 250 mg kg-1 did not affect the FC means (Table VII). However, it was determined that FC was significantly decreased for laying hens and diet containing 400 mg kg-1 [29, 31] and for broilers fed the diet containing 300 mg kg-1 concentration of B [21]. In view of these observations, growing chicks and laying hens may possess more greater tolerance to high B supplementation than broilers [18]. It is possible that, despite no significant differences, positive improvement in FCR obtained from B supplemented groups in period of 90-120 d may be seen profitable in laying hens of present study (Table VIII). ROSSI et al., [21] showed that 21 day aged broiler chicks given 120 mg kg-1 B had FCR values significantly higher than the control in their experiment 1, while in experiment 2 these values were not influenced by B additions. B addition

to diets in all groups did not cause significant effect on BW values (Table IX). However, BW values obtained at the end of the experiment were found higher than the control except for 200 mg kg-1 concentration of B group. It was also determined that BW values were found higher at the end of the experiment than those of at the start of the experiment in all groups. In agreement with our study WILSON and RUSZLER [31] in their experiment used 72 week old laying hens reported that B supplementation with 50, 100 and 200 mg kg1 increased the BW means when compared with the control. In the other study SEABORN and NIELSEN [24] showed that B addition at 3 µg/g diet significantly (P < 0.002) increased the final BW values in rats. It has been hypothesised that B is required for the synthesis of steroid hormones [12] and this stimulation is related to the hydroxylation processes of the cholesterol nucleus [23]. In animals, increases of steroid hormone synthesis reflect on improving the BW or growth rate. However, BW is negatively affected by the high levels of B supplementation. It has been reported that addition of 300 mg kg-1 B in broilers [19, 21] 400 mg kg-1 in laying hens [29, 31] and 400 mg kg-1 in growing pullets [30] significantly decreased the BW (P < 0.05). Some recently reviewed [2, 9, 15, 18] animal studies also support the concept that B affects Ca, P and Mg metabolism. NIELSEN [14] reported that, the apparent absorption and balance of Ca, Mg and P were found to be higher with a B

*

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. * days of experimental period TABLE VIII. — Effect of different levels of dietary boron on feed conversion ratio in laying hens fed for 120 days.

No differences were observed the groups (P > 0.05). Values represent the mean ± SEM of 8 replicates of 10 hens per treatment. TABLE IX. — Effect of different levels of dietary boron on body weight in laying hens fed for 120 days.

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KURTOGLU (V.) AND COLLABORATORS

Values represent the mean ± SEM of 6 groups of 12 layer hens per treatment. a,b,c Means within columns with no common superscripts are significantly different (P < 0.05), according to Duncan’s multiple range test. TABLE X — Effect of different levels of dietary boron on some blood parameters in laying hens fed for 120 days.

supplemented diet (2,72 µg/g) than with a diet deficient in B (0.16 µg/g) in rats. BROWN et al., [2] found that, Ca retention was improved by supplemental B, primarily because of increased Ca digestion in sheep. ROSSI et al., [20, 21] and WILSON and RUSZLER [30] indicated that administration of B to laying hens and broiler resulted in a significantly (P < 0.05) greater tibial bone ash percentage. Although we did not have any evidence, this observation [27, 30, 31] may suggest a positive effect of B on bone calcification in hens. HUNT [5] suggests that there is an interaction between B and Mg. In his trial, B enhanced bone resorption in a Mg adequate diet. In our study which is in agreement with these reports we found that B supplementation also increased the serum Ca (P < 0.05), P, and Mg levels (Table X). In conclusion, evidence from this study suggests that supplementation improved the damaged egg ratio especially in 150 and 250 mg kg-1 B supplemented groups. The other performance parameters from the present study were not influenced by the B supplementation. However 250 mg kg-1 B addition caused a significant improvement in Ca absorption. But further research is needed in order to observe the interaction between B and Ca required to obtain maximal beneficial effects on bone metabolism of laying hens.

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