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Effect of thermal stress on fertility and egg quality of Japanese quail
Author’s Accepted Manuscript Effect of thermal stress on fertility and egg quality of Japanese quail Mahmoud S. el-Tarabany
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S0306-4565(16)30124-3 http://dx.doi.org/10.1016/j.jtherbio.2016.08.004 TB1806
To appear in: Journal of Thermal Biology Received date: 29 April 2016 Revised date: 13 August 2016 Accepted date: 15 August 2016 Cite this article as: Mahmoud S. el-Tarabany, Effect of thermal stress on fertility and egg quality of Japanese quail, Journal of Thermal Biology, http://dx.doi.org/10.1016/j.jtherbio.2016.08.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Effect of thermal stress on fertility and egg quality of Japanese quail Mahmoud S. El-Tarabany* Department of Animal Wealth Development, Faculty of Veterinary Medicine, Zagazig University, Egypt.
*
Corresponding author: Mahmoud S. El-Tarabany
Email: [email protected], [email protected]
Short title: Heat stress and Fertility in quail.
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Abstract Heat stress is one of the major causes of a decreased performance of laying quail in tropical and subtropical countries. The aim of this study was to investigate the impact of temperature humidity index (THI) on fertility aspects, external and internal egg quality parameters in Japanese quail. One hundred and forty four (144) Japanese quail, 12 of weeks age, were used. Birds were divided randomly into three equal groups, control (at low THI, lower than 70), H1 (at moderate THI, 70-75) and H2 (at high THI, 76-80). Quail in the control and H1 groups had significant greater fertility (p = 0.021) and hatchability % (p = 0.037), compared with H2 group. Quail in the control group (at low THI) laid heavier egg weight with a higher external (egg weight (p = 0.03), shell thickness, shell weight, eggshell ratio and eggshell density (p=0.001)) and internal egg quality score (albumin weight (p = 0.026), yolk height (p = 0.003), yolk index (p = 0.039) and Haugh unit (p=0.001)). Otherwise, such quality traits were compromised in heat -stressed quail. At the high THI level, egg weight had a significant positive correlation with albumin weight (r = 0.58, p<0.01), yolk weight (r = 0.22, p < 0.05), albumen ratio (r = 0.17, p < 0.05), yolk height (r = 0.14, p<0.05) and yolk index (r = 0.18, p < 0.05), but was negatively correlated with yolk ratio (r = -0.15, p < 0.05). Japanese quail exposed to heat stress (THI over 75) revealed drop in fertility indices and egg quality traits, indicating a detrimental policy of economic income. Key words: Quail, THI, fertility, egg quality.
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1. Introduction Japanese quail (Coturnix japonica) is a domestic bird of economic importance for commercial egg and meat production in Egypt. The birds are hardy, resist disease, and require lower space and equipment utility (Minvielle, 2004). Japanese quail are considered the smallest avian species raised in farms, used for research purposes (Panda and Singh, 1990) and raised for meat and egg production (Punya Kumari et al., 2008). In European countries, they are reared mainly for meat in contrast to Asian countries that consider them dual-purpose (Minvielle, 1998). Overall egg quality is crucial for both poultry breeders and consumers. Poor egg quality results in major economic losses to the globalized egg industry, such as losses attributed to poor eggshell quality, which calculated to be in the order of 6–8% (Baylan et al., 2011). Measurements of egg quality can be assigned into two main divisions: external and internal traits (Song et al., 2000). External qualities such as egg weight and shell condition are significant for consumer’s acceptability (Wolanski et al., 2007), while the interior parameters are fundamental for the egg production industry (Song et al., 2000). The primary interior quality trait is thick albumin, considered an important criterion for egg freshness (Toussant and Latshaw, 1999). Eggs distinguished by a superior yolk index and Haugh unit are preferable (Ayorinde, 1987). All homeothermal animals including birds maintain a constant internal body temperature. According to thermodynamic basics, animals regularly exchange heat with the surronding environment, but this mechanism is exactly efficient at the animal’s thermoneutral range of environmental temperatures (Hannas, 1999; ElTarabany and El-Bayoumi, 2015). When environmental temperatures exceed the thermoneutral range, rectal temperature elevates, as well as respiratory rate, where
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panting is a mechanism used by birds to promote evaporative heat loss, thereby attempting to preserve body temperature (Silva et al., 2001). Thus, environmental temperature and humidity are substantial factors affecting egg production. Birds raised at environmental temperatures outside their thermoneutral zone may suffer severe physiological changes, including decreased feed intake, decreased feed efficiency and consequent drop in egg production and deteriorated egg quality, including light eggs, decreased yolk weight and percentage, and low specific gravity (Macari et al., 2004). To minimize these detrimental effects of thermal stress, many practical approaches have been suggested to enhance thermotolerance of birds, leading to minimize the adverse impacts on productivity (Del Vesco et al., 2014). Taking these facts into consideration, the aims of this trial were to elucidate the impact of temperature humidity index (THI) on egg quality traits in Japanese quail and estimate the correlations between external and internal egg quality traits. 2. Material and methods 2.1. Birds and management All procedures included in this trial were approved in accordance with the guidelines belonging to the Committee of Animal Ethics (ANWD-206), based on Ethics and Animal Welfare Committee guidelines (ICLAS). One hundred and forty four (144) adult Japanese quail at 12 weeks of age were selected with a homogenous body weight (156.27 g ± 1.49) . The birds were identified by means of wing bands and were assigned randomly into three equal groups (48 birds in each). Each group comprised 4 replicates (12 birds in each), where the allowed floor spaces in the cage was 250 cm2 / bird. The actual measures of each flat deck cage were 60 (L) x 50 (W) x 37 (H) cm.
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The groups were managed in experimental units provided with devices regulated to meet the required temperature and humidity for each experimental group, control [low temperature humidity index (THI), lower than 70; at 23.8 ± 0.7 °C and 58.5 ± 5.7 % RH], H1 (moderate THI, ranged 70-75; at 32.8 ± 0.8 °C and 57.7 ± 4.6 % RH) and H2 (high THI, ranged 76-80; at 35.8 ± 0.6 °C and 59.2 ± 4.5 % RH). Each unit measures 2.5 x 3.5 x 2.5 m, provided with an electrical air heater (power of 2000 Watts), and an air humidifier (4.5 L capacity). The THI was calculated according to formula reported by Zulovich and DeShazer (1990) and modified by Bayhan et al. (2013). THI =0.6 Tdb + 0.4 Twb, where Tdb = dry-bulb temperature, °C; Twb = wet-bulb temperature, °C. The temperature and relative humidity were adjusted using automated thermo-hygrometers. Throughout the period of experiment (6 weeks), birds in the H1 and H2 groups were exposed to controlled temperature and humidity for 8 hours daily, beginning at 8 a.m. A standard layers mash (20.0 % crude protein, 11937 KJ/kg ME) was provided (Table 1). The lighting schedule was 15h light: 9h dark for the whole experimental period. One male: two females mating ratio was applied to ensure fertility aspects. Initial and end of the experiment body weights were determined using a standardized electronic balance (1202 MP, Sartorius, Germany). To record egg quality traits, random egg samples (n=160/group; N=480) were collected over 4 consecutive weeks. Carefully, eggs were labelled immediately after collection and the studied traits of egg quality were taken within 10h of collection. 2.2. Fertility indices Eggs were labeled per experimental group and incubated in automatic incubator, with controlled humidity (60%) and temperature (37.6°C) parameters. On the 15 th day, incubated eggs were transferred to a hatching sector and after two days the hatched
5
chicks were transferred to the rearing area. Unhatched eggs were opened to determine fertility and hatchability percentages. Fertility and hatchability indices over the experimental period (repeated in the form of four sequent batches at 15, 16, 17 and 18 weeks of age) were calculated. Fertility percentage was computed as the of number of fertile eggs divided by total number of eggs incubated. Hatchability percentage was calculated as the number of chicks hatched divided by total number of eggs incubated. 2.3. External egg quality traits Egg weight was measured using an electronic balance (1202 MP, Sartorius, Germany) with accuracy +/- 0.01g. Egg width and egg length (mm) were calibrated using an electronic digital device with accuracy +/- 0.001 mm. Egg shape index was computed as 100 × (egg width / egg length) according to Das et al. (2010). Eggshell thickness (mm) was calibrated via a standardized electronic digital device once the eggshell was dried at room temperature, taken as the average of estimates from both ends and the equator of the examined eggs (Das et al., 2010). Eggshell weight (g) was determined using a standardized Sartorius 1202 MP balance after the shell had been dried at room temperature. Eggshell ratio was computed as 100 × (shell weight / egg weight). The area of egg surface (cm2) was estimated as 3.9782W 0.7056, where W equal to egg weight (Sezer, 2007). Egg shell density was computed as shell weight (mg) ⁄ egg surface area (cm2) (Vits et al., 2005). 2.4. Internal egg quality traits After recording the external parameters, the estimates of internal quality components were recorded. Gently, breaking the egg was performed using a sharp scalpel and emptying the contents onto a glass surface. The albumin was gently separated from the yolk to weigh the yolk mass. The albumin mass was computed via subtracting the 6
weights of shell plus yolk from the total egg weight. Regarding weighing process, the glass surface was washed and dried after each weighing. The yolk and albumin dimensions (mm) were estimated using an electronic device (Reddy et al., 1979). The following traits of the internal egg quality were achieved according to Romanoff and Romanoff (1949). Yolk index value was calculated as 100 x [Yolk height (cm) / Yolk diameter (cm)]. Yolk ratio was calculated as Yolk weight (g) / Egg weight (g) x 100. Albumin ratio was computed as 100 × [Albumin weight (g) / Egg weight (g)], and Haugh units (HU) were determined according to previous formula reported by Haugh (1937). HU equal 100 log (H + 7.57 - 1.7W0.37), H: Albumin height (mm), W: Egg weight (g). 2.5. Statistical analysis All statistical methods were applied using SAS statistical system Package V9.2 (SAS, 2002). After testing normality using Kolmogorov-Smirnov procedure, data were analyzed by means of one-way analysis of variance (ANOVA) through the applied general linear models (GLM) procedure. The MIXED model included the fixed effects of the treated groups (3 levels) and the random effects of replicates. The Duncan’s multiple range test was performed to compare means. Coefficients of Pearson correlation were estimated to evaluate the relationship between external and internal egg quality traits. 3. Results The overall fertility percentages in the control (84.8 %) and H 1 (83.7 %) groups were significantly (p=0.021) higher than those reported in the H2 (78.9 %) group (Fig 1). Furthermore, hatchability percentages in the control (80.2 %) and H 1 (79.4 %) groups
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were significantly (p=0.037) higher than those reported in the H2 (74.1 %) group (Fig 2) Quail housed at low THI level (control group) had a relatively higher external egg quality score in comparison with the heat-stressed group (H2, THI 76-80), based on: egg weight, egg width, eggshell thickness, eggshell weight, eggshell percentage, egg surface area and egg shell density (Table 2 and Fig 3). Similarly, the control group had a higher score for internal parameters compared with H2 including: albumin height, albumin weight and ratio, yolk height, yolk diameter, yolk index and Haugh unit (Table 2, and Fig 4 and 5). However, there were no significant differences (p>0.05) between thermoneutral group and H1 group for albumin height, yolk diameter and yolk index. At the high THI value, egg weight had a significant positive correlation with albumin weight (r = 0.58, P<0.01), albumin ratio (r = 0.17, p < 0.05), yolk height (r = 0.14, P<0.05), yolk weight (r = 0.22, p < 0.05), yolk diameter (r = 0.33, p < 0.01) and yolk index (r = 0.18, p < 0.05) but was negatively correlated with yolk ratio (r = -0.15, p < 0.05). Moreover, egg width had positive correlation estimates with albumin weight (r = 0.25, p<0.01) and yolk index (r = 0.16, p < 0.05). Eggshell weight was positively correlated with albumin weight (r = 0.19, p < 0.05), albumin height (r = 0.48, p < 0.01), yolk height (r = 0.32, p<0.01), yolk diameter (r = 0.19, p < 0.05), yolk index (r = 0.22, p < 0.01) and Haugh unit (r = 0.69, p < 0.01) (Table 3). Shell thickness had a significant positive correlation with albumin height (r = 0.38, p < 0.01), yolk height (r = 0.34, p < 0.01), yolk diameter (r = 0.28, p < 0.05), yolk index (r = 0.24, p < 0.01) and Haugh unit (r = 0.22, p < 0.05). Eggshell density was positively correlated with albumin height (r = 0.34, p < 0.01), yolk height (r = 0.21, p <
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0.05), yolk index (r = 0.19, p < 0.05) and Haugh unit (r = 0.26, p < 0.01) but was negatively correlated with albumin weight (r = -0.16, p < 0.05) (Table 3). 4. Discussion This trial was primarily conducted to inspect the influence of THI level on fertility aspects and egg quality criteria in Japanese quail. The negative impact of high ambient temperature on performance depends on the magnitude and duration of heat stress (Renaudeau et al., 2012). However, Sykes and Fataftah (1986) indicated that acclimation of domestic birds occurs within the first few days of thermal stress. Regarding egg quality parameters in Japanese quail, there have been conflicting results which may be assigned to various factors including: genetic differences, environmental and managerial conditions, health status, birds’ age and diet composition (Kul and Seker, 2004; Alkan et al., 2010, El-Tarabany, 2016). Physiological variations leading to compromise ovarian follicles maturation have also been proposed as influencing factors (Palmer and Bahr, 1992). Eggs from the control group were heavier when compared with the heatstressed birds. Such results are in agreement with those reported by Vercese et al. (2012), but inconsistent with the former results obtained by Emery et al. (1984). Heat stress has been reported to reduce feed intake, as well as digestibility of different components of the diet (Bonnet et al., 1997). Furthermore, when ambient temperature exceeds the thermoneutral zone of a bird, feed consumption is decreased to minimize the production of metabolic heat (Swennen et al., 2007), which adversely affects performance and profitability (Quinteiro-Filho et al., 2010).The reduction in feed intake by birds may be attributed to various physiological responses to heat stress, aimed at limiting the excessive endogenous heat produced in the body due to feed metabolism (Khan and Sarda, 2003). Furthermore, it has 9
been reported that exposure to high temperatures reduce plasma protein concentration and plasma Ca concentration, both of which are required for egg formation (Zhou et al., 1998). Thermal stress causes a series pattern of physiological and metabolic modulations in birds such as increased body temperature, panting and related respiratory alkalosis, and altered metabolic status evolved by reduced concentrations of plasma triiodothyronine (Deyhim and Teeter, 1991). Laying birds in the current trial exposed to high thermal stress (THI 76-80) had compromised fertility and hatchability percentage in comparison with birds exposed to THI up to 75. In related work, similar compromised trends in fertility, hatchability and egg production traits were reported previously (Mahmoud et al., 1996). They stated that heatstressed laying hens had a depressed egg production due to imponderables in calcium-estrogen relationship. This implies that thermal stress decreases albumin consistency, yolk size and calcium deposit in the egg shell. The depression in the ovarian blood flow is a possible mechanism for the reduction of the ovarian function; a differential ovarian blood flow pattern was detected in laying hens subjected to elevated ambient temperatures (Mashaly et al., 2004). The values of egg shape indices as markers for shell thickness and shell ratio is questionable (Abu Tabeekh, 2011), but they might serve a more applied advantage in defining the eggshell strength (Yannakopoulos and Tserveni-Gousi, 1986). In the current experiment, results reported in the thermoneutral group were compatible with the findings of Abu Tabeekh (2011). Furthermore, the estimates of shell thickness, weight and percentage were greater than those reported by Zita et al. (2013). In this study the eggshell weight was superior in the thermoneutral group in comparison with heat-stressed groups which is consistent with Vercese et al. (2012). The higher eggshell weight might be attributed to higher egg weight (Karaman and Bascillar,
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2012), as heavier eggs exist for a longer period in the female reproductive tract mainly in the uterine portion for calcification deposition and pigmentation (Akram et al., 2013). The greater egg surface area in the control group might be related to larger eggs having a greater surface area and an elongated shape (Akram et al., 2013). The eggshell density was greater in the thermonuetral group compared to the heat-stressed groups and this may be due to the greater egg size overall in the thermonuteral group. Sezer (2007) found that the eggshell density decreased as shell weight decreased and egg weight increased. The deteriorated shell quality in the present trial may be partially attributed to a decreased Ca level in plasma. It has been recorded that estimated level of plasma Ca was significantly decreased in the laying hens confined to high temperatures. In addition, former reports concluded that Ca uptake by epithelial cells in the duodenum was decreased by exposure to high ambient temperatures (Mahmoud et al., 1996). High ambient temperature may affect the feed (and consequently calcium) intake of the bird, thus resulting in a diminished availability of calcium for shell formation. Furthermore, this catalyzes the mechanism of bone resorption, resulting in an adaptive hyperphosphataemia which prohibts the depostion of calcium carbonate material in the shell gland of laying birds (Rama and Nagalakshmi, 1998). However, respiratory evaporative heat loss is the principal pathway of heat loss in the birds; however, reduced feed intake is also considered an adaptive mechanism (Blem, 2000). Moreover, Van kampen (1981) suggested a limited scope for increasing heat loss by vasodilatation in birds. It was noted that eggshell formation is under the effect of the acid-base balance in blood. Laying hens will try to conquer thermal stress by panting. However, this causes a reduction in the availability of carbon dioxide (CO2) in the hens’ blood, a condition recognized as respiratory alkalosis. As egg shells are composed mainly from calcium carbonate
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(CaCO3), this reduction in blood CO2 levels, consolidated with an increase in blood pH and a subsequent decrease in Ca ions utilized by the shell gland, leads to thinner or softer shelled eggs (Arima et al., 1976). The albumin height in the current trial was higher in the control group than that in the heat-stressed groups; however, such estimates in the control group were comparable to those reported by others (Kul and Seker, 2004; El-Tarabany, 2015). The estimated height of albumin and yolk increased with increasing egg size (Sekeroglu and Altuntas, 2009). Furthermore, measures reported for albumin weight in the control group corroborate a previous work (Genchev, 2012). It has been reported that most the estimated yolk height has significant impacts on other egg quality parameters (Alkan et al., 2010). The yolk index is the most favorable egg quality (Ayorinde, 1987). In the present trial, the estimated yolk index in the thermoneutral group was similar to that recorded by Zita et al. (2013), but greater than that estimated by others (Kul and Seker, 2004). Albumin viscosity is the most important quality traits. Unfortunately, it might be evaluated only indirectly by determining the albumin height and its surface area. The Haugh unit score is considered as one of the superior methods to calculate egg quality (El-Tarabany et al., 2015). The higher the Haugh unit, the better the egg quality (Haugh, 1937). The reported estimates of Haugh unit herein, in control and heat stressed groups, were comparable with former trials (Vercese et al., 2012). The superior Haugh unit in control hens could be attributed to improved viscosity of albumin, resulting in a higher estimate of albumin height (Akram et al., 2013). In the present study, the deteriorated albumen and yolk quality in heat-stressed groups might be attributed to the compromised functions of both ovary and oviduct (Arima et al., 1976).
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The current results indicated that
lower egg weights
at high THI were
positively correlated with albumin weight and ratio, yolk weight, yolk height and diameter, and yolk index, however, were negatively correlated with yolk ratio and such estimates were comparable to that recorded by other researchers (Kul and Seker, 2004; Zita et al., 2013). Furthermore, shell weight had positive correlation with albumin and yolk height, yolk index and Haugh unit as reported formerly (Kul and Seker, 2004; Alkan et al., 2010). Minvielle et al. (1997) detected that the genetic correlation between fresh egg weight and the weight of other internal components was positive and estimated to be more than 0.5. Therefore, most of the internal egg quality traits were positively correlated with egg weight and eggshell weight. Accordingly, improving the egg weight, as well as eggshell weight will ameliorate most of the egg quality parameters. In conclusion, laying Japanese quail subjected to the stress of high thermal environment (mainly at THI over 75), showed deteriorated fertility indices, external and internal egg quality parameters, reflecting the numerous economical hazards of such condition. That’s why appropriate ways should be used to relieve these stressors as possible in order to maximize production and profit. Accordingly, various strategies have been suggested to alleviate the detrimental effects of thermal stress by maintaining optimum feed intake, electrolytic and water balance, as well as supplementation of micronutrients such as vitamins and minerals to meet the suspected high requirements during heat stress. Supplemental dietary Chromium (Sahin et al., 2002) offers an applicable way to minimize the losses in performance of Japanese
quail
reared
under
heat
stress.
Furthermore,
dietary
lycopene
supplementation may restore the heat stress-induced impairment in antioxidant status of laying hens (Sahin et al., 2006).
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performance and carcass characteristics in heat-stressed Japanese quail. J. Therm. Biol. 31, 307–312 Sahin, K., Ozbey, O., Ondericikim, M., Aysondu, M.H., 2002. Chromium supplementation can alleviate negative effects of heat stress on egg production, egg quality and some serum metabolites of laying Japanese quail. J. Nutr. 132, 1265–1268. SAS Institute, 2002. SAS/STAT users guide. SAS Institute Inc., Cary, NC, USA. Sekeroglu, A., Altuntas, E., 2009. Effects of egg weight on egg quality characteristics. Journal of the Science of Food and Agriculture 89, 379-383. Sezer, M., 2007. Heritability of exterior egg quality traits in Japanese quail. Journal of Applied Biological Science 1, 37-40. Silva, M.A.N., Silva, I.J.O., Piedade, S.M.S., Martins, E., Coelho, A.A., Savino, V.J.M., 2001. Resistência ao estresse calórico em frangos de corte de pescoço pelado. Revista Brasileira de Ciência Avícola 3, 27-33. Song, K.T., Choi, S.H., Oh, H.R., 2000. A comparison of egg quality of pheasant, chukar, quail and guinea fowl. Asian-Australasian Journal of Animal Sciences 13, 986-990. Swennen, Q., Verhulst, P.J., Collin, A., Bordas, A., Verbeke, K., Vansant, G., Decuyper E., Buyse, J., 2007.Further investigations on the role of diet-induced hermogenesis in the regulation of feed intake in chickens: comparison of adult
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cockerels E62 Bottje and Carstens of lines selected for high or low residual feed intake.Poult.Sci.86, 1960–1971. Sykes, A.H., Fataftah, A.R.A.,1986.Acclimatisationofthefowltointermittentacute heat stress.Br.Poult.Sci.27,289–300. Toussant, M.J., Latshaw, J.D., 1999. Ovomucin content and composition in chicken eggs with different interior. Journal of the Science of Food and Agriculture 79, 1666-1670. Van kampen, M.,1981.Water balance of colostomised and non-colostomised hens at different ambient temperatures.Br.Poult.Sci.22,17–23. Vercese, F., Garcia, E.A., Sartori, J.R., Pontes Silva, A., Faitarone, A.B.G., Berto, D.A., Molino, A., Pelícia, K., 2012. Performance and Egg Quality of Japanese Quails Submitted to Cyclic Heat Stress. Revista Brasileira de Ciência Avícola 14, 37-41. Vits, A., Weitzenbuerger, D., Hamann, H., Distl, O., 2005. Production, egg quality, bone strength, claw length, and keel bone deformities of laying hens housed in furnished cages with different group sizes. Poultry Science 84, 1511-1519. Wolanski, N.J., Renema, R.A., Robinson, F.E., Carney, V.L., Fancher, B.I., 2007. Relationships among egg characteristics, chick measurements, and early growth traits in ten broiler breeder strains. Poultry Science 86, 1784-1792. Yannakopoulos, A.L., Tserveni-Gousi, A.S., 1986. Quality characteristics of quail eggs. British Poultry Science 27, 171-176. Zhou, W.T., Fujita, M., Yamamoto, S., Iwasaki, K., Ikawa, R., Oyama, H., Horikawa, H., 1998. Effects of glucose in drinking water on the changes in whole blood viscosity and plasma osmolality of broiler chickens during high temperature exposure. Poultry Science 77, 644-647. 20
Zita, L, Ledvinka, Z ., Klesalova, L., 2103. The effect of the age of Japanese quails on certain egg quality traits and their relationships. Veterinarski Arhiv 83, 223232. Zulovich, J.M., DeShazer, J.A., 1990. Estimating egg production declines at high environmental temperatures and humidifies. ASAE Paper No. 90-4021. St. Joseph, Mich.: ASAE.
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Table 1. Diet composition in the laying period % diet Ingredients Yellow corn 64.50 Soybean meal (44%) 20.50 Concentrate (52%) 10.00 Di- calcium phosphate 2.31 Limestone 0.96 DL- methionine 0.09 Lysine 0.08 Vitamin and trace mineral 0.30 Premix 1.06 Coccidostate 0.10 Antioxidant 0.10 Calculated analysis ME (KJ / kg) 11937 Crude protein (cp %) 20.00 Calcium% 2.33 Available phosphorus% 0.66 Lysine % 1.04 Methionine % 0.52
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Table 2. Effects of temperature humidity index (THI) level on the external and internal egg quality traits in Japanese quail 1
Trait
2
CON
Body weight (18th wk, g)
H1
233.5 a
5
ADFI (g/day)
219.4 b
3
H2
4
RSE
P value
201.8c
3.2
0.001
Egg weight (g)
26.5a 12.15a
21.6b 11.68b
20.6b 11.54b
0.4 0.21
0.038 0.003
Egg width (mm)
25.76
25.75
25.70
0.42
0.695
Egg length (mm)
31.78
32.03
31.93
0.46
0.877
Egg shape index (%)
78.01
77.33
78.52
0.13
0.237
Shell thickness (mm)
0.24a
0.21b
0.20b
0.01
0.001
Shell weight (g)
1.30a
1.08b
1.05b
0.05
0.001
Eggshell %
10.66a
9.15b
8.99b
0.03
0.001
Egg surface area (cm2)
23.50a
22.31b
22.39b
0.41
0.001
Eggshell density (mg/cm2)
48.98a
44.01b
43.10b
0.73
0.001
Albumin height (mm)
5.07a
4.86ab
3.84b
0.07
0.031
Albumin weight (g)
6.68a
6.25b
6.11b
0.14
0.026
Albumin ratio %
54.45
53.54
52.22
0.17
0.274
Yolk height (mm)
10.78a
8.96b
8.24c
0.18
0.003
Yolk diameter (mm)
24.40a
23.80ab
23.14b
0.43
0.026
Yolk weight (g)
4.28
4.15
4.11
0.08
0.512
Yolk ratio %
35.95
36.01
36.11
0.11
0.912
Yolk index (%)
42.72a
39.01ab
35.13b
0.08
0.039
Haugh Unit
92.37a
87.33b
85.66b
0.22
0.001
1
2
3
CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80. RSE: residual standard error. Heat-stressed groups exposed to controlled temperature and humidity for 8 hours daily, beginning at 8 a.m, throughout the experimental period (4 weeks). 5 ADFI: average daily feed intake. a,b,c Values within a row with different superscripts differ significantly. 4
Table 3. Correlation coefficients among the external and internal egg quality traits in H2 Japanese quail 23
0.38a 0.48a 0.43a 0.13b
Eggshell density
Egg surface area
0.02
Eggshell %
Egg shape index
0.04
Shell weight
Egg length
0.10
Shell thickness
Egg width
Internal egg quality traits
Egg weight
External egg quality traits
0.34a
Albumin height
0.09
Albumin weight
0.58a 0.25a 0.46a -0.16b
0.10 0.19b -0.18b 0.51a -0.16b
Albumin ratio
0.17a 0.12 0.19b -0.17b
0.04 0.10 -0.02
Yolk height
0.14b -0.09 0.07
0.02
0.34a 0.32a 0.32a 0.21b
Yolk diameter
0.33a 0.14b 0.25a
-0.06
0.28b 0.19b 0.03
0.07
-0.02
Yolk weight
0.22b 0.06
0.11
0.18b
0.04
0.18b 0.12
0.06 -0.08
0.17b -0.05 0.21b
Yolk ratio
-0.15b -0.13b -0.15
0.17b
0.03 -0.09 0.04 -0.10
Yolk index
0.18b 0.16b 0.11
0.03
0.24a 0.22a 0.31a 0.15b 0.19b
Haugh Unit
0.02 -0.08 -0.12
0.08
0.22b 0.69a 0.65 a 0.05
a
0.02
0.26a
P<0.01, b P<0.05.
Figure legend Fig. 1. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on fertility percentages at 4 sequent weeks in laying quail. Fig. 2. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on hatchability percentages at 4 sequent weeks in laying quail. Fig. 3. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on shell weight and shell thickness in laying quail.
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Fig. 4. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on Yolk index and Haugh units in laying quail. Fig. 5. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on Yolk height and Yolk diameter in laying quail.
Highlights This study evaluates the effect of different THI levels on fertility indices in Quail
The current work investigates the effect of different THI levels on external and internal egg quality in Quail.
Correlation coefficients have been estimated among external and internal egg quality parameters
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PII: DOI: Reference:
S0306-4565(16)30124-3 http://dx.doi.org/10.1016/j.jtherbio.2016.08.004 TB1806
To appear in: Journal of Thermal Biology Received date: 29 April 2016 Revised date: 13 August 2016 Accepted date: 15 August 2016 Cite this article as: Mahmoud S. el-Tarabany, Effect of thermal stress on fertility and egg quality of Japanese quail, Journal of Thermal Biology, http://dx.doi.org/10.1016/j.jtherbio.2016.08.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Effect of thermal stress on fertility and egg quality of Japanese quail Mahmoud S. El-Tarabany* Department of Animal Wealth Development, Faculty of Veterinary Medicine, Zagazig University, Egypt.
*
Corresponding author: Mahmoud S. El-Tarabany
Email: [email protected], [email protected]
Short title: Heat stress and Fertility in quail.
1
Abstract Heat stress is one of the major causes of a decreased performance of laying quail in tropical and subtropical countries. The aim of this study was to investigate the impact of temperature humidity index (THI) on fertility aspects, external and internal egg quality parameters in Japanese quail. One hundred and forty four (144) Japanese quail, 12 of weeks age, were used. Birds were divided randomly into three equal groups, control (at low THI, lower than 70), H1 (at moderate THI, 70-75) and H2 (at high THI, 76-80). Quail in the control and H1 groups had significant greater fertility (p = 0.021) and hatchability % (p = 0.037), compared with H2 group. Quail in the control group (at low THI) laid heavier egg weight with a higher external (egg weight (p = 0.03), shell thickness, shell weight, eggshell ratio and eggshell density (p=0.001)) and internal egg quality score (albumin weight (p = 0.026), yolk height (p = 0.003), yolk index (p = 0.039) and Haugh unit (p=0.001)). Otherwise, such quality traits were compromised in heat -stressed quail. At the high THI level, egg weight had a significant positive correlation with albumin weight (r = 0.58, p<0.01), yolk weight (r = 0.22, p < 0.05), albumen ratio (r = 0.17, p < 0.05), yolk height (r = 0.14, p<0.05) and yolk index (r = 0.18, p < 0.05), but was negatively correlated with yolk ratio (r = -0.15, p < 0.05). Japanese quail exposed to heat stress (THI over 75) revealed drop in fertility indices and egg quality traits, indicating a detrimental policy of economic income. Key words: Quail, THI, fertility, egg quality.
2
1. Introduction Japanese quail (Coturnix japonica) is a domestic bird of economic importance for commercial egg and meat production in Egypt. The birds are hardy, resist disease, and require lower space and equipment utility (Minvielle, 2004). Japanese quail are considered the smallest avian species raised in farms, used for research purposes (Panda and Singh, 1990) and raised for meat and egg production (Punya Kumari et al., 2008). In European countries, they are reared mainly for meat in contrast to Asian countries that consider them dual-purpose (Minvielle, 1998). Overall egg quality is crucial for both poultry breeders and consumers. Poor egg quality results in major economic losses to the globalized egg industry, such as losses attributed to poor eggshell quality, which calculated to be in the order of 6–8% (Baylan et al., 2011). Measurements of egg quality can be assigned into two main divisions: external and internal traits (Song et al., 2000). External qualities such as egg weight and shell condition are significant for consumer’s acceptability (Wolanski et al., 2007), while the interior parameters are fundamental for the egg production industry (Song et al., 2000). The primary interior quality trait is thick albumin, considered an important criterion for egg freshness (Toussant and Latshaw, 1999). Eggs distinguished by a superior yolk index and Haugh unit are preferable (Ayorinde, 1987). All homeothermal animals including birds maintain a constant internal body temperature. According to thermodynamic basics, animals regularly exchange heat with the surronding environment, but this mechanism is exactly efficient at the animal’s thermoneutral range of environmental temperatures (Hannas, 1999; ElTarabany and El-Bayoumi, 2015). When environmental temperatures exceed the thermoneutral range, rectal temperature elevates, as well as respiratory rate, where
3
panting is a mechanism used by birds to promote evaporative heat loss, thereby attempting to preserve body temperature (Silva et al., 2001). Thus, environmental temperature and humidity are substantial factors affecting egg production. Birds raised at environmental temperatures outside their thermoneutral zone may suffer severe physiological changes, including decreased feed intake, decreased feed efficiency and consequent drop in egg production and deteriorated egg quality, including light eggs, decreased yolk weight and percentage, and low specific gravity (Macari et al., 2004). To minimize these detrimental effects of thermal stress, many practical approaches have been suggested to enhance thermotolerance of birds, leading to minimize the adverse impacts on productivity (Del Vesco et al., 2014). Taking these facts into consideration, the aims of this trial were to elucidate the impact of temperature humidity index (THI) on egg quality traits in Japanese quail and estimate the correlations between external and internal egg quality traits. 2. Material and methods 2.1. Birds and management All procedures included in this trial were approved in accordance with the guidelines belonging to the Committee of Animal Ethics (ANWD-206), based on Ethics and Animal Welfare Committee guidelines (ICLAS). One hundred and forty four (144) adult Japanese quail at 12 weeks of age were selected with a homogenous body weight (156.27 g ± 1.49) . The birds were identified by means of wing bands and were assigned randomly into three equal groups (48 birds in each). Each group comprised 4 replicates (12 birds in each), where the allowed floor spaces in the cage was 250 cm2 / bird. The actual measures of each flat deck cage were 60 (L) x 50 (W) x 37 (H) cm.
4
The groups were managed in experimental units provided with devices regulated to meet the required temperature and humidity for each experimental group, control [low temperature humidity index (THI), lower than 70; at 23.8 ± 0.7 °C and 58.5 ± 5.7 % RH], H1 (moderate THI, ranged 70-75; at 32.8 ± 0.8 °C and 57.7 ± 4.6 % RH) and H2 (high THI, ranged 76-80; at 35.8 ± 0.6 °C and 59.2 ± 4.5 % RH). Each unit measures 2.5 x 3.5 x 2.5 m, provided with an electrical air heater (power of 2000 Watts), and an air humidifier (4.5 L capacity). The THI was calculated according to formula reported by Zulovich and DeShazer (1990) and modified by Bayhan et al. (2013). THI =0.6 Tdb + 0.4 Twb, where Tdb = dry-bulb temperature, °C; Twb = wet-bulb temperature, °C. The temperature and relative humidity were adjusted using automated thermo-hygrometers. Throughout the period of experiment (6 weeks), birds in the H1 and H2 groups were exposed to controlled temperature and humidity for 8 hours daily, beginning at 8 a.m. A standard layers mash (20.0 % crude protein, 11937 KJ/kg ME) was provided (Table 1). The lighting schedule was 15h light: 9h dark for the whole experimental period. One male: two females mating ratio was applied to ensure fertility aspects. Initial and end of the experiment body weights were determined using a standardized electronic balance (1202 MP, Sartorius, Germany). To record egg quality traits, random egg samples (n=160/group; N=480) were collected over 4 consecutive weeks. Carefully, eggs were labelled immediately after collection and the studied traits of egg quality were taken within 10h of collection. 2.2. Fertility indices Eggs were labeled per experimental group and incubated in automatic incubator, with controlled humidity (60%) and temperature (37.6°C) parameters. On the 15 th day, incubated eggs were transferred to a hatching sector and after two days the hatched
5
chicks were transferred to the rearing area. Unhatched eggs were opened to determine fertility and hatchability percentages. Fertility and hatchability indices over the experimental period (repeated in the form of four sequent batches at 15, 16, 17 and 18 weeks of age) were calculated. Fertility percentage was computed as the of number of fertile eggs divided by total number of eggs incubated. Hatchability percentage was calculated as the number of chicks hatched divided by total number of eggs incubated. 2.3. External egg quality traits Egg weight was measured using an electronic balance (1202 MP, Sartorius, Germany) with accuracy +/- 0.01g. Egg width and egg length (mm) were calibrated using an electronic digital device with accuracy +/- 0.001 mm. Egg shape index was computed as 100 × (egg width / egg length) according to Das et al. (2010). Eggshell thickness (mm) was calibrated via a standardized electronic digital device once the eggshell was dried at room temperature, taken as the average of estimates from both ends and the equator of the examined eggs (Das et al., 2010). Eggshell weight (g) was determined using a standardized Sartorius 1202 MP balance after the shell had been dried at room temperature. Eggshell ratio was computed as 100 × (shell weight / egg weight). The area of egg surface (cm2) was estimated as 3.9782W 0.7056, where W equal to egg weight (Sezer, 2007). Egg shell density was computed as shell weight (mg) ⁄ egg surface area (cm2) (Vits et al., 2005). 2.4. Internal egg quality traits After recording the external parameters, the estimates of internal quality components were recorded. Gently, breaking the egg was performed using a sharp scalpel and emptying the contents onto a glass surface. The albumin was gently separated from the yolk to weigh the yolk mass. The albumin mass was computed via subtracting the 6
weights of shell plus yolk from the total egg weight. Regarding weighing process, the glass surface was washed and dried after each weighing. The yolk and albumin dimensions (mm) were estimated using an electronic device (Reddy et al., 1979). The following traits of the internal egg quality were achieved according to Romanoff and Romanoff (1949). Yolk index value was calculated as 100 x [Yolk height (cm) / Yolk diameter (cm)]. Yolk ratio was calculated as Yolk weight (g) / Egg weight (g) x 100. Albumin ratio was computed as 100 × [Albumin weight (g) / Egg weight (g)], and Haugh units (HU) were determined according to previous formula reported by Haugh (1937). HU equal 100 log (H + 7.57 - 1.7W0.37), H: Albumin height (mm), W: Egg weight (g). 2.5. Statistical analysis All statistical methods were applied using SAS statistical system Package V9.2 (SAS, 2002). After testing normality using Kolmogorov-Smirnov procedure, data were analyzed by means of one-way analysis of variance (ANOVA) through the applied general linear models (GLM) procedure. The MIXED model included the fixed effects of the treated groups (3 levels) and the random effects of replicates. The Duncan’s multiple range test was performed to compare means. Coefficients of Pearson correlation were estimated to evaluate the relationship between external and internal egg quality traits. 3. Results The overall fertility percentages in the control (84.8 %) and H 1 (83.7 %) groups were significantly (p=0.021) higher than those reported in the H2 (78.9 %) group (Fig 1). Furthermore, hatchability percentages in the control (80.2 %) and H 1 (79.4 %) groups
7
were significantly (p=0.037) higher than those reported in the H2 (74.1 %) group (Fig 2) Quail housed at low THI level (control group) had a relatively higher external egg quality score in comparison with the heat-stressed group (H2, THI 76-80), based on: egg weight, egg width, eggshell thickness, eggshell weight, eggshell percentage, egg surface area and egg shell density (Table 2 and Fig 3). Similarly, the control group had a higher score for internal parameters compared with H2 including: albumin height, albumin weight and ratio, yolk height, yolk diameter, yolk index and Haugh unit (Table 2, and Fig 4 and 5). However, there were no significant differences (p>0.05) between thermoneutral group and H1 group for albumin height, yolk diameter and yolk index. At the high THI value, egg weight had a significant positive correlation with albumin weight (r = 0.58, P<0.01), albumin ratio (r = 0.17, p < 0.05), yolk height (r = 0.14, P<0.05), yolk weight (r = 0.22, p < 0.05), yolk diameter (r = 0.33, p < 0.01) and yolk index (r = 0.18, p < 0.05) but was negatively correlated with yolk ratio (r = -0.15, p < 0.05). Moreover, egg width had positive correlation estimates with albumin weight (r = 0.25, p<0.01) and yolk index (r = 0.16, p < 0.05). Eggshell weight was positively correlated with albumin weight (r = 0.19, p < 0.05), albumin height (r = 0.48, p < 0.01), yolk height (r = 0.32, p<0.01), yolk diameter (r = 0.19, p < 0.05), yolk index (r = 0.22, p < 0.01) and Haugh unit (r = 0.69, p < 0.01) (Table 3). Shell thickness had a significant positive correlation with albumin height (r = 0.38, p < 0.01), yolk height (r = 0.34, p < 0.01), yolk diameter (r = 0.28, p < 0.05), yolk index (r = 0.24, p < 0.01) and Haugh unit (r = 0.22, p < 0.05). Eggshell density was positively correlated with albumin height (r = 0.34, p < 0.01), yolk height (r = 0.21, p <
8
0.05), yolk index (r = 0.19, p < 0.05) and Haugh unit (r = 0.26, p < 0.01) but was negatively correlated with albumin weight (r = -0.16, p < 0.05) (Table 3). 4. Discussion This trial was primarily conducted to inspect the influence of THI level on fertility aspects and egg quality criteria in Japanese quail. The negative impact of high ambient temperature on performance depends on the magnitude and duration of heat stress (Renaudeau et al., 2012). However, Sykes and Fataftah (1986) indicated that acclimation of domestic birds occurs within the first few days of thermal stress. Regarding egg quality parameters in Japanese quail, there have been conflicting results which may be assigned to various factors including: genetic differences, environmental and managerial conditions, health status, birds’ age and diet composition (Kul and Seker, 2004; Alkan et al., 2010, El-Tarabany, 2016). Physiological variations leading to compromise ovarian follicles maturation have also been proposed as influencing factors (Palmer and Bahr, 1992). Eggs from the control group were heavier when compared with the heatstressed birds. Such results are in agreement with those reported by Vercese et al. (2012), but inconsistent with the former results obtained by Emery et al. (1984). Heat stress has been reported to reduce feed intake, as well as digestibility of different components of the diet (Bonnet et al., 1997). Furthermore, when ambient temperature exceeds the thermoneutral zone of a bird, feed consumption is decreased to minimize the production of metabolic heat (Swennen et al., 2007), which adversely affects performance and profitability (Quinteiro-Filho et al., 2010).The reduction in feed intake by birds may be attributed to various physiological responses to heat stress, aimed at limiting the excessive endogenous heat produced in the body due to feed metabolism (Khan and Sarda, 2003). Furthermore, it has 9
been reported that exposure to high temperatures reduce plasma protein concentration and plasma Ca concentration, both of which are required for egg formation (Zhou et al., 1998). Thermal stress causes a series pattern of physiological and metabolic modulations in birds such as increased body temperature, panting and related respiratory alkalosis, and altered metabolic status evolved by reduced concentrations of plasma triiodothyronine (Deyhim and Teeter, 1991). Laying birds in the current trial exposed to high thermal stress (THI 76-80) had compromised fertility and hatchability percentage in comparison with birds exposed to THI up to 75. In related work, similar compromised trends in fertility, hatchability and egg production traits were reported previously (Mahmoud et al., 1996). They stated that heatstressed laying hens had a depressed egg production due to imponderables in calcium-estrogen relationship. This implies that thermal stress decreases albumin consistency, yolk size and calcium deposit in the egg shell. The depression in the ovarian blood flow is a possible mechanism for the reduction of the ovarian function; a differential ovarian blood flow pattern was detected in laying hens subjected to elevated ambient temperatures (Mashaly et al., 2004). The values of egg shape indices as markers for shell thickness and shell ratio is questionable (Abu Tabeekh, 2011), but they might serve a more applied advantage in defining the eggshell strength (Yannakopoulos and Tserveni-Gousi, 1986). In the current experiment, results reported in the thermoneutral group were compatible with the findings of Abu Tabeekh (2011). Furthermore, the estimates of shell thickness, weight and percentage were greater than those reported by Zita et al. (2013). In this study the eggshell weight was superior in the thermoneutral group in comparison with heat-stressed groups which is consistent with Vercese et al. (2012). The higher eggshell weight might be attributed to higher egg weight (Karaman and Bascillar,
10
2012), as heavier eggs exist for a longer period in the female reproductive tract mainly in the uterine portion for calcification deposition and pigmentation (Akram et al., 2013). The greater egg surface area in the control group might be related to larger eggs having a greater surface area and an elongated shape (Akram et al., 2013). The eggshell density was greater in the thermonuetral group compared to the heat-stressed groups and this may be due to the greater egg size overall in the thermonuteral group. Sezer (2007) found that the eggshell density decreased as shell weight decreased and egg weight increased. The deteriorated shell quality in the present trial may be partially attributed to a decreased Ca level in plasma. It has been recorded that estimated level of plasma Ca was significantly decreased in the laying hens confined to high temperatures. In addition, former reports concluded that Ca uptake by epithelial cells in the duodenum was decreased by exposure to high ambient temperatures (Mahmoud et al., 1996). High ambient temperature may affect the feed (and consequently calcium) intake of the bird, thus resulting in a diminished availability of calcium for shell formation. Furthermore, this catalyzes the mechanism of bone resorption, resulting in an adaptive hyperphosphataemia which prohibts the depostion of calcium carbonate material in the shell gland of laying birds (Rama and Nagalakshmi, 1998). However, respiratory evaporative heat loss is the principal pathway of heat loss in the birds; however, reduced feed intake is also considered an adaptive mechanism (Blem, 2000). Moreover, Van kampen (1981) suggested a limited scope for increasing heat loss by vasodilatation in birds. It was noted that eggshell formation is under the effect of the acid-base balance in blood. Laying hens will try to conquer thermal stress by panting. However, this causes a reduction in the availability of carbon dioxide (CO2) in the hens’ blood, a condition recognized as respiratory alkalosis. As egg shells are composed mainly from calcium carbonate
11
(CaCO3), this reduction in blood CO2 levels, consolidated with an increase in blood pH and a subsequent decrease in Ca ions utilized by the shell gland, leads to thinner or softer shelled eggs (Arima et al., 1976). The albumin height in the current trial was higher in the control group than that in the heat-stressed groups; however, such estimates in the control group were comparable to those reported by others (Kul and Seker, 2004; El-Tarabany, 2015). The estimated height of albumin and yolk increased with increasing egg size (Sekeroglu and Altuntas, 2009). Furthermore, measures reported for albumin weight in the control group corroborate a previous work (Genchev, 2012). It has been reported that most the estimated yolk height has significant impacts on other egg quality parameters (Alkan et al., 2010). The yolk index is the most favorable egg quality (Ayorinde, 1987). In the present trial, the estimated yolk index in the thermoneutral group was similar to that recorded by Zita et al. (2013), but greater than that estimated by others (Kul and Seker, 2004). Albumin viscosity is the most important quality traits. Unfortunately, it might be evaluated only indirectly by determining the albumin height and its surface area. The Haugh unit score is considered as one of the superior methods to calculate egg quality (El-Tarabany et al., 2015). The higher the Haugh unit, the better the egg quality (Haugh, 1937). The reported estimates of Haugh unit herein, in control and heat stressed groups, were comparable with former trials (Vercese et al., 2012). The superior Haugh unit in control hens could be attributed to improved viscosity of albumin, resulting in a higher estimate of albumin height (Akram et al., 2013). In the present study, the deteriorated albumen and yolk quality in heat-stressed groups might be attributed to the compromised functions of both ovary and oviduct (Arima et al., 1976).
12
The current results indicated that
lower egg weights
at high THI were
positively correlated with albumin weight and ratio, yolk weight, yolk height and diameter, and yolk index, however, were negatively correlated with yolk ratio and such estimates were comparable to that recorded by other researchers (Kul and Seker, 2004; Zita et al., 2013). Furthermore, shell weight had positive correlation with albumin and yolk height, yolk index and Haugh unit as reported formerly (Kul and Seker, 2004; Alkan et al., 2010). Minvielle et al. (1997) detected that the genetic correlation between fresh egg weight and the weight of other internal components was positive and estimated to be more than 0.5. Therefore, most of the internal egg quality traits were positively correlated with egg weight and eggshell weight. Accordingly, improving the egg weight, as well as eggshell weight will ameliorate most of the egg quality parameters. In conclusion, laying Japanese quail subjected to the stress of high thermal environment (mainly at THI over 75), showed deteriorated fertility indices, external and internal egg quality parameters, reflecting the numerous economical hazards of such condition. That’s why appropriate ways should be used to relieve these stressors as possible in order to maximize production and profit. Accordingly, various strategies have been suggested to alleviate the detrimental effects of thermal stress by maintaining optimum feed intake, electrolytic and water balance, as well as supplementation of micronutrients such as vitamins and minerals to meet the suspected high requirements during heat stress. Supplemental dietary Chromium (Sahin et al., 2002) offers an applicable way to minimize the losses in performance of Japanese
quail
reared
under
heat
stress.
Furthermore,
dietary
lycopene
supplementation may restore the heat stress-induced impairment in antioxidant status of laying hens (Sahin et al., 2006).
13
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Table 1. Diet composition in the laying period % diet Ingredients Yellow corn 64.50 Soybean meal (44%) 20.50 Concentrate (52%) 10.00 Di- calcium phosphate 2.31 Limestone 0.96 DL- methionine 0.09 Lysine 0.08 Vitamin and trace mineral 0.30 Premix 1.06 Coccidostate 0.10 Antioxidant 0.10 Calculated analysis ME (KJ / kg) 11937 Crude protein (cp %) 20.00 Calcium% 2.33 Available phosphorus% 0.66 Lysine % 1.04 Methionine % 0.52
22
Table 2. Effects of temperature humidity index (THI) level on the external and internal egg quality traits in Japanese quail 1
Trait
2
CON
Body weight (18th wk, g)
H1
233.5 a
5
ADFI (g/day)
219.4 b
3
H2
4
RSE
P value
201.8c
3.2
0.001
Egg weight (g)
26.5a 12.15a
21.6b 11.68b
20.6b 11.54b
0.4 0.21
0.038 0.003
Egg width (mm)
25.76
25.75
25.70
0.42
0.695
Egg length (mm)
31.78
32.03
31.93
0.46
0.877
Egg shape index (%)
78.01
77.33
78.52
0.13
0.237
Shell thickness (mm)
0.24a
0.21b
0.20b
0.01
0.001
Shell weight (g)
1.30a
1.08b
1.05b
0.05
0.001
Eggshell %
10.66a
9.15b
8.99b
0.03
0.001
Egg surface area (cm2)
23.50a
22.31b
22.39b
0.41
0.001
Eggshell density (mg/cm2)
48.98a
44.01b
43.10b
0.73
0.001
Albumin height (mm)
5.07a
4.86ab
3.84b
0.07
0.031
Albumin weight (g)
6.68a
6.25b
6.11b
0.14
0.026
Albumin ratio %
54.45
53.54
52.22
0.17
0.274
Yolk height (mm)
10.78a
8.96b
8.24c
0.18
0.003
Yolk diameter (mm)
24.40a
23.80ab
23.14b
0.43
0.026
Yolk weight (g)
4.28
4.15
4.11
0.08
0.512
Yolk ratio %
35.95
36.01
36.11
0.11
0.912
Yolk index (%)
42.72a
39.01ab
35.13b
0.08
0.039
Haugh Unit
92.37a
87.33b
85.66b
0.22
0.001
1
2
3
CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80. RSE: residual standard error. Heat-stressed groups exposed to controlled temperature and humidity for 8 hours daily, beginning at 8 a.m, throughout the experimental period (4 weeks). 5 ADFI: average daily feed intake. a,b,c Values within a row with different superscripts differ significantly. 4
Table 3. Correlation coefficients among the external and internal egg quality traits in H2 Japanese quail 23
0.38a 0.48a 0.43a 0.13b
Eggshell density
Egg surface area
0.02
Eggshell %
Egg shape index
0.04
Shell weight
Egg length
0.10
Shell thickness
Egg width
Internal egg quality traits
Egg weight
External egg quality traits
0.34a
Albumin height
0.09
Albumin weight
0.58a 0.25a 0.46a -0.16b
0.10 0.19b -0.18b 0.51a -0.16b
Albumin ratio
0.17a 0.12 0.19b -0.17b
0.04 0.10 -0.02
Yolk height
0.14b -0.09 0.07
0.02
0.34a 0.32a 0.32a 0.21b
Yolk diameter
0.33a 0.14b 0.25a
-0.06
0.28b 0.19b 0.03
0.07
-0.02
Yolk weight
0.22b 0.06
0.11
0.18b
0.04
0.18b 0.12
0.06 -0.08
0.17b -0.05 0.21b
Yolk ratio
-0.15b -0.13b -0.15
0.17b
0.03 -0.09 0.04 -0.10
Yolk index
0.18b 0.16b 0.11
0.03
0.24a 0.22a 0.31a 0.15b 0.19b
Haugh Unit
0.02 -0.08 -0.12
0.08
0.22b 0.69a 0.65 a 0.05
a
0.02
0.26a
P<0.01, b P<0.05.
Figure legend Fig. 1. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on fertility percentages at 4 sequent weeks in laying quail. Fig. 2. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on hatchability percentages at 4 sequent weeks in laying quail. Fig. 3. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on shell weight and shell thickness in laying quail.
24
Fig. 4. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on Yolk index and Haugh units in laying quail. Fig. 5. Effect of THI zone [CON: low THI, less than 70; H1: moderate THI, 70-75; H2: high THI, 76-80] on Yolk height and Yolk diameter in laying quail.
Highlights This study evaluates the effect of different THI levels on fertility indices in Quail
The current work investigates the effect of different THI levels on external and internal egg quality in Quail.
Correlation coefficients have been estimated among external and internal egg quality parameters
25
26
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