Some hormonal changes related to some trace elements deficiency in ration of male lambs

doi:10.21608/ejah.2022.220757

Some hormonal changes related to some trace elements deficiency in ration of male lambs

Egyptian Journal of Animal Health

Article 2, Volume 2, Issue 1, January 2022, Pages 13-20 PDF (1005.19 K)

Document Type: Original researches

DOI: 10.21608/ejah.2022.220757

Abstract

Trace element deficiency in male lambs is a serious problem. It refers to either insufficient nutrients or mineral elements imbalance. This work aimed to investigate the hormonal and some biochemical changes related to some trace element deficiency and the effect of mineral mixture supplementation on these changes. To achieve this aim we induced trace element deficiency in a tested male lambs group (N=10) belonged to our sheep herd and received a mineral mixture as a feed supplement for 10 days. The analysis of tested diet revealed protein 12.32%, calcium 1.21%, phosphorus 0.27%, and zinc 25.96 mg/kg DM. While the control healthy group (N=10) received a traditional diet. The results of serum hormones and biochemical analysis of tested group revealed a significant (P˂0.05) decrease in TSH, T3, T3/T4, testosterone, free testosterone, SHBG, GH, albumin and zinc, with a significant (P˂0.05) increase in T4, total protein and globulin compared to control healthy group. On the other hand, the results obtained after mineral mixture supplementation revealed a significant (P˂0.05) increase of TSH, T3, T3/T4, testosterone, free testosterone, SHBG, GH, albumin and zinc. Also, a significant (P˂0.05) decrease in T4, total protein, and globulin was observed compared with this group before mineral mixture supplementation, with observation of the changes were gradually toward recovery. Moreover, insignificant changes were recorded in calcium, phosphorus and iodine. In conclusion to trace element deficiency have an effect on vital hormones with extension to metabolic process, general health condition and proper growth of male lambs.

Keywords

Trace element deficiency; mineral mixture; hormones; zinc

Full Text

Some hormonal changes related to some trace elements deficiency in ration of male lambs

Hanan A. Tag El Din, Hamada M. Yousif, Reda A. A. Rezk

Biochemistry, Toxicology and Feed Deficiency Department, Animal Health Research Institute (AHRI), Dokki, Giza.

ABSTRACT

Trace element deficiency in male lambs is a serious problem. It refers to either insufficient nutrients or mineral elements imbalance. This work aimed to investigate the hormonal and some biochemical changes related to some trace element deficiency and the effect of mineral mixture supplementation on these changes. To achieve this aim we induced trace element deficiency in a tested male lambs (N=10) group belonged to our sheep herd and received a mineral mixture as a feed supplement for 10 days. The analysis of tested diet revealed protein 12.32%, calcium 1.21%, phosphorus 0.27%, and zinc 25.96 mg/kg DM. While the control healthy group (N=10) received a traditional diet. The results of serum hormones and biochemical analysis of tested group revealed a significant (P˂0.05) decrease in TSH, T3, T3/T4, testosterone, free testosterone, SHBG, GH, albumin and zinc, with a significant (P˂0.05) increase in T4, total protein and globulin compared to control healthy group. On the other hand, the results obtained after mineral mixture supplementation revealed a significant (P˂0.05) increase of TSH, T3, T3/T4, testosterone, free testosterone, SHBG, GH, albumin and zinc. Also, a significant (P˂0.05) decrease in T4, total protein, and globulin was observed compared with this group before mineral mixture supplementation, with observation of the changes were gradually toward recovery. Moreover, insignificant changes were recorded in calcium, phosphorus and iodine. In conclusion to trace element deficiency have an effect on vital hormones with extension to metabolic process, general health condition and proper growth of male lambs.

KEY WORDS: Trace element deficiency, mineral mixture, hormones, zinc.

INTRODUCTION

Trace elements are important for raising lambs. So a new fed ingredients could be used in lamb diet that will be contributed to increase weight gains and improvement of meat quality (Valença et al. 2020). However, the goal of productive efﬁciency in feedlot animals, relies upon many factors, including the strategy of how diet is fed (De-Oliveira et al. 2020). Increasing the frequency of feeding diets composed of hay and concentrates could stimulate the appetite of feedlot and productivity (Saldanha et al. 2021). The proper growth and improvement of growing lambs mainly rely upon the level of nutrition, on contrary insufficient nutrition may decrease the growth performance of intensively managed sheep (Ebrahimi et al. 2007).

Mineral elements are nutritionally essential for small ruminants. These include macrominerals as calcium, phosphorous, sodium, chlorine, potassium, magnesium, and sulfur. Trace elements, or microminerals as copper, selenium, zinc, iodine, cobalt, iron, manganese and molybdenum. Improvement of trace element nutrition that meet consumer perceptions and preferences, is a current cost effective challenge (Radostitis et al. 2007).

Zinc (Zn) is an important microminerals essential for all animals (Suttle 2010). The counseled minimal necessities of zinc are 20 mg/kg DM for growth and 33 mg/kg DM for maintenance of normal reproductive function including male testicular development and female pregnancy and lactation. The high calcium diet (about 1.2-1.8% calcium) adversely affect zinc utilization (Mills et al. 1967). The effect of zinc on reproductive functions besides its effect on hormones (impacting on gonadotropins excretion, influencing the sperm motility and their ability to penetrate the ova) (Noakes et al. 2001). Zinc deficiency results in decreased levels of thyroid hormones secretion which affecting the normal feed metabolism and resting metabolic rate. This low level also badly affects testosterone levels (Yan et al. 2010).

Iodine is necessary for thyroid hormone synthesis with normal basal metabolic rate (BMR) and reproductive energy metabolism (Suttle 2010). Iodine is essential for thyroxin synthesis with general metabolic regulation, particularly mitochondrial activity. Decreased thyroxin is associated with non-specific signs of poor growth, loss of libido, hence affects the animal reproductive performance (Sargison et al. 2011).

Calcium (Ca) and phosphorus (P) are closely interrelated, particularly in the development and maintenance of skeletal system function. The high calcium diet may cause a deficiency of another elements, as phosphorus, magnesium, iron, iodine, zinc, and manganese (NRC 2007).

Blood thyroid hormone level indicates the changes in thyroid gland activity and circulating thyroid hormones that reflects the metabolic and nutritional status of the animal (Todini 2007; Antunović et al. 2019).

Additional supplementations are generally required because the native forages often not fulfills the growth requirements (Ward & Gifford 2017). Therefore mineral mixtures are usually mixed with concentrates diet for improving the growth rate, reproduction, feed utilization, immune response and general health (Kalita et al. 2003).The supplementation of mineral mixture in conventional adequate diets of lambs were helpful in improving the daily body weight gain, feed efficiency and feed conversion ratio(Kharb et al. 2017).

The aim of this work is to investigate the effects of nutritional trace elements deficiency on some hormones and serum biochemical with the role of mineral mixture supplementation in recovery of the changes occurred.

MATERIALS AND METHODS

Experimental design

The study were established in a sheep farm in Kalubia governorate. Ten male lambs aged 9-12 months were isolated received diet composed of imbalanced trace elements and examined before and after mineral mixture supplementation. The animals were compared to control healthy group (N=10) that feeding by traditional methods (using roughage, corn grains, wheat bran, barely, concentrates, wheat straw, rice straw).

Supplementation

Mineral mixture, composed of a group of minerals zinc, manganese, iron, copper, iodine, selenium, cobalt, sodium chloride, phosphorus and calcium carbonates manufactured by AGRIVET Company, Egypt. This mineral mixture added to concentrated diet as feed additives according to the manufactured company (3 kg for one ton concentrate) for 10 days.

Samples

The sample of diets were collected from the concentrate diet of the animals in a clean dry plastic bag and preserved at room temperature until examination.

The blood sampling were collected from the jugular vein (Pugh 2002) from control andat the time of disease detection and after the end of 10 days of mineral mixture supplementation in the deficient group. The blood samples were centrifuged at 5000 rpm for 5 minutes to obtain the serum samples. The clear sera were aspirated carefully by automatic pipette and transferred into clean dry labeled Eppendorf tubes, and stored at −20°Ctill examination.

Methods

1- Concentrated diet examination

The collected concentrated diet samples were examined forprotein, fat, carbohydrates, TDN, crude fiber, calcium, phosphorus, zinc, iron, copper, magnesium, sodium, potassium and iodine according to AOAC (2005). Also aflatoxin and ocratoxin were examined.

2- Serum examination

2-1- Biochemical determination

Special kits (Stain Bio Company) were used for spectrophotometric determination of total protein, albumin, and a special kits (Biodiagnostic Company) were used for spectrophotometric determination of zinc, calcium, inorganic phosphorus and iodine.

2-2- Hormonal Determination

Quantitative determination of serum thyroid stimulating hormone (TSH); Triiodothyronine (T3) and thyroxin (T4) were determined by using enzyme immunoassay ELISA kit (Immunospec corporation, USA, catalog No. E29-227; E29-229 and E29-230, respectively). The assay is based on a solid phase enzyme-linked immunosorbent assay with sensitivity 0.2µIU/ml; 0.25ng/ml and 0.5 µg/dl for TSH, T3 and T4 respectively. Also, quantitative determination of serum testosterone, free testosterone, sex hormone binding globulin (SHBG) and growth hormone were determined by using enzyme immunoassay ELISA kit (abia testosterone, catalog No. Dk 040 013; DBC, Canada, catalog No. CAN-FTE-260; Cloud-Clone Crop., catalog No. E-0095BO and catalog No. MBS-743413 with sensitivity 0.2 ng/ml; 0.018 pg/ml; 1 ng/ml and 0.1ng/ml respectively.

Statistical analysis

The data were statistically analyzed using one way (ANOVA) as previously described (Bailey 2008) using SPSS 16 software to test the significance difference between control group and the diseased group before and after mineral mixture supplementation. The results were demonstrated as means ± SE. The results were considered statistically significant when P˂0.05.

RESULTS

The clinical examination of diseased animal noted that the animals were weakened, depressed with decreased appetite and weight loss. The result of feed analysis revealed negative (-ve) result of aflatoxin and ocratoxin, protein 12.32%, TDN 69%, fat 1.51%, fiber 30.38%, calcium 1.21%, phosphorus 0.27% and zinc 25.96 mg/kg dry matter basis (DM). The other nutrients and minerals examined were within the reference range of nutrient requirement.

The results of serum biochemical examination of diseased animals before mineral supplementation (Tab. 1) revealed a significant (P˂0.05) increase in total protein, globulin with significant (P˂0.05) decrease in albumin level compared to control healthy group. On the other hand, the serum biochemical examination after mineral supplementation revealed a significant (P˂0.05) decrease in total protein and globulin with significant (P˂0.05) increase in albumin compared to this group before mineral supplementation. The serum minerals examination (Tab. 1) in diseased group before mineral supplementation revealed significant (P˂0.05) decrease in zinc level, but non-significant changes after mineral supplementation compared to control healthy group. Calcium, inorganic phosphorus and iodine revealed non-significant changes between groups.

The results of serum hormones examination (Tab. 2) revealed significant (P˂0.05) decrease in TSH, T3, T3/T4, testosterone, free testosterone, SHBG and GH with a significant (P˂0.05) increase in T4 of the animals suffered from nutritional trace element deficiency before mineral mixture supplementation compared to control healthy group. On the other hand, the results after mineral mixture supplementation revealed significant (P˂0.05) increase in TSH, T3, T3/T4, testosterone, free testosterone, SHBG and GH with a significant (P˂0.05) decrease in T4 in comparing to this group before mineral mixture supplementation and these changes were nearly toward the control level.

Table (1): Results of serum biochemical and minerals of the trace element deficient group before and after mineral mixture supplementation compared to control healthy group.

Parameters

Control group

Trace element deficient group

Before supplementation

After supplementation

Total Protein

(g/dl)

7.045^b

±0.357

8.092^a

±0.473

7.275^b

±0.298

Albumin

(g/dl)

3.442^a

±0.151

3.041^c

±0.17

3.265 ^b

±0.168

Globulin

(g/dl)

3.603^c

±0.234

5.051^a

±0.332

4.01^b

±0.22

Zinc

(µg/dl)

100.08^a

±5.07

80.86^b

±5.34

97.94^a

±5.9

Calcium

(mg/dl)

9.12 ^a

±0.33

9.348 ^a

±0.416

9.284^a

±0.334

Inorganic Phosphorus

(mg/dl)

5.218^a

±0.296

5.14 ^a

±0.55

5.193 ^a

±0.308

Iodine

(µg/dl)

81.24 ^a

±7.31

82.31 ^a

±7.62

81.82 ^a

±6.22

Data are expressed as mean ± SE of 10 samples.

^{a, b, c} Means within the same raw with different superscripts are significantly different at (P˂0.05).

Table (2): Results of serum hormonal changes of the trace element deficient group before and after mineral mixture supplementation compared to control healthy group.

Parameters

Control group

Trace element deficient group

Before supplementation

After supplementation

TSH

(µIU/ml)

0.43^a

±0.052

0.312^b

±0.054

0.384^a

±0.051

Total T3

(ng/ml)

1.817^a

±0.0696

1.49^c

±0.116

1.658^b

±0.055

Total T4

(µg/dl)

54.49^c

±0.644

69.86^a

±1.37

60.8^b

±0.96

T3/T4

(%)

0.033^a

±0.0012

0.021^c

±0.002

0.027^b

±0.0012

Testosterone

(ng/ml)

4.429^a

±0.428

2.512^b

±0.556

4.503^a

±0.598

Free Testosterone

(pg/ml)

0.333^a

±0.054

0.158^b

±0.071

0.288^a

±0.046

SHBG

(ng/ml)

1630.8^a

±75.9

1406.4^b

±98.1

1616.8^a

±75.4

Growth hormone

(ng/ml)

1.18^a

±0.047

0.126^c

±0.082

1.11^b

±0.071

Data are expressed as mean ± SE of 10 samples.

^{a, b, c}Means within the same raw with different superscripts are significantly different at (P˂0.05).

DISCUSSION

The clinical examination of diseased animal showed that there were weakness, depression, decreased appetite and weight loss. These signs were in agreement with NRC (2007). Malnutrition has a prominent effect on the production and reproductive functions (Abecia et al. 2006).The result of feed analysis revealed calcium 1.21%, phosphorus 0.27%, zinc 25.96 mg/kg DM, the other nutrients and minerals within the reference range of nutrient requirements. While, the daily nutrient requirement are calcium 0.42% and phosphorus 0.21% according to NRC (2007). The nutrient requirements of zinc were 33 mg/kg DM needed for testicular maturation and normal reproductive function in male lambs (Mills et al. 1967). These results provided imbalance in minerals and trace element as the diet is high in calcium and low in zinc.

The serum minerals in diseased animals revealed decreased zinc level. This result agreed with Ibrahim et al. (2016) who reported experimental zinc deficiency after feeding diet contains 26ppm zinc with high calcium level after the 6th week. This also may be attributed to the elevated level of calcium in diet that adversely affects zinc utilization (Mills et al. 1967).

The analysis of serum biochemistry in diseased animals showed elevated total protein and globulin with decreased albumin. An increase in serum globulin indicates the development of an antibody response to the present antigen and deprived diet stress factors with nutritional zinc deficiency. Furthermore, increase the total protein is related to increased globulin (Van den Broek et al. 2000). On the other hand decreased albumin may be attributed to decreased appetite and the distorted hepatic protein metabolism. Loss of appetite and subsequently weight losses may develop changes in hepatic function and decrease in nutrients digestion (Fisher & Crookshank 1982).

The result of serum hormones of diseased animals revealed increased T4 and decrease in T3 and TSH. These results may be related to the nutritional zinc deficiency as a result of oxidative stress that leading to thyroid dysfunction (Ganapathy & Volpe 1999). Zinc deficiency in the body may result in decreased levels of secretion of thyroid hormones (Yan et al. 2010). The activity of type I-5’deiodinase enzyme and consequently the conversion of T4 to T3 is curbed in nutritional zinc deficiency (Wada & King 1986). Both the hypothalamus and hypophysis are susceptible to nutritional zinc deficiency. Consequently, it was suggested that zinc might be necessary for the enzymes involved in thyroid releasing hormone (TRH) and TSH synthesis (Pekary et al. 1991). Moreover, Tag El-Din et al. (2015) found that decrease in T3 levels in ewes may be due to zinc deficiency recorded in these animals as it has been reported that zinc participate in synthesis of protein and essential for thyroid function since involved in T3 binding to its nuclear receptor (Liu et al. 2001).

The decreased testosterone, free testosterone and sex hormone binding globulin (SHBG) in diseased animals may be related to nutritional zinc deficiency. Thus, Zn is closely related to the male reproductive hormones. Severe and moderate zinc deficiency in males causes hypogonadism (Prasad et al. 1996). Low level of zinc may affect the production of these hormones, as well as testosterone level (Yan et al. 2010). Zinc deficiency disrupts the activity of angiotensin converting enzyme, which is involved in the production of adrenal androgens (Kwok et al. 2010). This disruption results in decreased testosterone production and the inhibition of spermatogenesis (Bedwal & Bahuguna 1994). Nutritional zinc deficiency in male rat considerably inhibits testosterone (Ozturk et al. 2005). Also, deficiency of zinc suppresses the receptor activity of androgenic hormones and thus zinc has a critical part in the regulation of male reproductive functions (Om & Chung 1996). These results investigate the relation between nutrition trace element mainly zinc and hormones. Changes in serum hormones are indicator for nutritional status, animal healthy and reproduction status (Todini 2007; Antunović et al. 2019).

Drop in level of growth hormone (GH) may be related to nutritional trace element deficiency mainly zinc deficiency (Roth & Kirchgessner 1997). Moreover, zinc deficiency resulted in decrease the affinity of growth hormone receptors and growth factor binding protein-3 (IGFBP-3) in rat (McNall et al. 1995).

The serum analysis of animals after mineral mixture supplementation revealed an increased level of testosterone, free testosterone, SHBG, TSH, T3, T3/T4, GH and zinc with decreased T4 level in comparison with this group before mineral supplementation. These results provided the role of mineral mixture supplementation in compensation of zinc and leading to the recovery of vital and reproductive hormones. Supplementation of mineral mixture in conventional lamb diets is helpful in improving the daily body weight gain, feed efficiency and conversion ratio, production and reproduction performance (Kalita et al. 2003; Kharb et al. 2017).

CONCLUSION

Based upon the results of this work it could be concluded that; Nutritional trace elements deficiencies mainly zinc in male lambs is a serious problem. It refers to either insufficient or imbalance between mineral and trace elements levels. The main nutritional trace element deficiency in this work was zinc deficiency that occurred due to high calcium diet. Nutritional zinc deficiency leading to changes in thyroid hormones, growth hormone and sexual hormones not only but also some serum biochemical. Mineral mixture supplementation in conventional lamb diet was helpful in improvement of reproductive hormones and for compensation of mineral requirements.

Recommendation

Nutritional trace elements requirement are very necessary to be concerned by using total mixed ration (TMR) either during growing and fattening or reproduction of lambs. Also using a traditional method of feeding is satisfy.
Supplementation of mineral mixture in the lamb diets is recommended and could be used all over the period of growing, fattening and reproduction.

References

Abecia JA, Sosa C, Forcada F, Meikle A. 2006. The effect of under nutrition on the establishment of pregnancy in the ewe. Reprod. Nutr. Dev., 46: 367–378. doi: 10.1051/rnd:2006018.

Antunović, Z, Marić I, Klir Z, Mioč B, Novoselec J. 2019. The effect of concentrates on production traits, biochemical parameters and thyroid hormones concentration in Dubrovnik sheep fed forage based-diets. Veterinarski Arhiv, 89(4): 505-518. doi:10.24099/vet.arhiv.0559.

AOAC. 2005. Ofﬁcial Methods of Analysis of the Association of Ofﬁcial Analytical Chemists, 18th edn. Association of Ofﬁcial Analytical Chemists Inc.: Gaithersburg, MD, USA.

Bailey RA. 2008. Design of Comparative Experiments. Cambridge University Press. Pp: 116-128.

Bedwal RS, Bahuguna A. 1994. Zinc, copper and selenium in reproduction. Experientia, 50: 626-640.

De-Oliveira CRN, Santos SA, Mariz LDS, Carvalho GGP, De-Azevêdo JAG, Tosto MSL, Dos-Santos ACS. 2020. Dietary phase-feeding as feedlot strategy for Santa Ines lambs: Performance, N retention and meat quality. Livest. Sci. 239: 104106.

Ebrahimi R, Ahmadi HR, Zamiri MJ, Rowghani E. 2007. Effect of energy and protein levels on feedlot performance and carcass characteristics of Mehraban ram lambs. Pakistan Journal of Biological Sciences, 15(15): 1679–1684.

Fisher WF, Crookshank HR. 1982. Effects of Psoroptes ovis (Acariña: Psoroptidae) on certain biochemical constituents of cattle serum. Veterinary Parasitology, 11: 241-251.

Ganapathy S, Volpe SL. 1999. Zinc, exercise and thyroid hormone function. Crit. Rev. Food Sci. Nutr., 39: 369-390.

Ibrahim SO, Helal MA, Abd El Raof YM, Elattar HM. 2016. Experimental study on zinc deficiency in sheep. BVMJ. 31(1): 110-118.

Kalita DJ, Sarmah BC, Sarmah DN. 2003. Effect of mineral supplementation on retention blood mineral profile of Assam local goats. Indian Journal of Animal Nutrition, 20: 467-470.

Kharb R, Kumar G, Dhama K, Akbar MA. 2017. Effect of Mineral Supplementation on Nutrient Utilization and Growth Performance of Lambs. Journal of Experimental Biology and Agricultural Sciences, 5(6): 774-779.

Kwok T, Ohlsson C, Vandenput L, Tang N, Zhang YF, Tomlinson B, Leung PC. 2010. ACE inhibitor use was associated with lower serum dehydroepiandrosterone concentrations in older men. Clin. Chim. Acta. 411: 1122-1125.

Liu N, Pingsheng L, Qing X, Li Z, Zhiying Z, Zhengzhou W, Yanfen L, Wejing F, Lianzhen Z. 2001. Elements in erythrocytes of population. Trace Element Res. 84: 37-43.

McNall AD, Etherton TD, Fosmire GJ. 1995. The impaired growth induced by zinc deficiency in rats is associated with decreased expression of the hepatic insulin-like growth. J. Nutr. 125: 874-879.

Mills CF, Dalgarno AC, Williams RB, Quarterman J. 1967. Zinc deficiency and the zinc requirements of calves and lambs. Br. J. Nutr. 21: 751-768.

NRC. 2007. Nutrient requirements of small ruminants (sheep, goats, cervids and new world camelides). National Research Council. The national academies press. Washington, D.C., p: 362.

Noakes DE, Parkinson TJ, England GCW. 2001. Arthur’s Veterinary Reproduction and Obstetrics. W .B. Saunders, London – Edinburgh – New York – Philadephia – St Louis – Sydney – Toronto, 8th edn. p: 868.

Om AS, Chung KW. 1996. Dietary zinc deficiency alters 5 alpha-reduction and aromatization of testosterone and androgen and estrogen receptors in rat liver. J. Nutr. 126: 842-848.

Ozturk A, Baltaci AK, Mogulkoc R, Oztekin E, Kul A. 2005. The effects of zinc deficiency and testosterone supplementation on leptin levels in castrated rats and their relation with LH, FSH and testosterone. Neuro Endocrinol. Lett. 26: 548-554.

Pekary AE, Lukaski HC, Mena I, Hershman JM. 1991. Processing of TRH precursor peptides in rat brain and pituitary is zinc dependent. Peptides, 12: 1025-1032.

Prasad AS, Mantzoros CS, Beck FW, Hess JW, Brewer GJ. 1996. Zinc status and serum testosterone levels of healthy adults. Nutrition, 12: 344-348.

Pugh DG. 2002. A Text Book of Sheep and Goat Medicine. 1st edn. W.B. Saunders, USA. ISBN-10: 0-7216-9052-1.

Radostits OM, Gay CC, Hinchcliff KW, Constable PD. 2007. Veterinary Medicine, a Text Book of the Diseases of Cattle, Sheep, Pigs, Goats and Horses. 10th edn. W.B. Saunders, USA.

Roth HP, Kirchgessner M. 1997. Course of concentration changes growth hormone, IGF-1, insulin and C-peptide in serum, pituitary and liver of zinc deficient rats. J. Anim. Phys. Anim. Nutr. 77: 91-101.

Saldanha RB, Dos Santos ACP, Alba HDR, Rodrigues CS , Pina DD-S, Cirne LGA, Santos SA, Pires AJV, Silva RR, Tosto MSL, Bento SC, Grimaldi AB, Becker CA, De-Carvalho GGP. 2021. Effect of Feeding Frequency on Intake, Digestibility, Ingestive Behavior, Performance, Carcass Characteristics, and Meat Quality of Male Feedlot Lambs. Agriculture, 11: 776.

Sargison ND, West DM, Clark RG. 2011. The effect of iodine deficiency on ewe fertility and perinatal lamb mortality. New Zealand Veterinary Journal, 46(2): 72-75.

Suttle NF. 2010. Mineral Nutrition of Livestock, 4th edn. CABi Publishing, USA.

Tag El-Din HA, Abo El-Soud SM, Snosy SAA, El-Ekhnawey K, El-Said FG. 2015. A trial to pinpoint some causes of infertility in ewes from the New Valley governorate. Egypt. J. Chem. Environ. Health, 1(1): 134-152.

Todini L. 2007. Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors. Animal, 1(7): 997-1008. doi: 10.1017/S1751731107000262.

Valença RDL, Sobrinho AGD, Borghi TH, Meza DAR, De-Andrade N, Silva LG, Bezerra LR. 2020. Performance, carcass traits, physicochemical properties and fatty acids composition of lamb’s meat fed diets with marine microalgae meal (Schizochytrium sp.). Livest. Sci. 243: 104387.

Van den Broek, AH, Huntiey JF, MacHeii J, Tayior M, Bates P, Groves B, Miiier HR. 2000. Cutaneous and systemic responses during primary and challenge infestations of sheep with the sheep scab mite, Psoroptes ovis. Parasit Immunol. 22 (8): 407-414. doi: 10.1046/j.1365-3024.2000.00318.x.

Wada L, King JC. 1986. Effect of low zinc intakes on basal metabolic rate, thyroid hormones and protein utilization in adult men. J. Nutr. 116: 1045-1053. doi: 10.1093/jn/116.6.1045.

Ward M, Gifford C. 2017. Sheep Nutrition (Circular 685). College of Agriculture, Consumer and Environmental sciences. Las Cruces: New Mexico State University Cooperative Extension Service.

Yan M, Hardin K, Ho E. 2010. Differential response to zinc-induced apoptosis in benign prostate hyperplasia and prostate cancer cells. J. Nutr. Biochem. 21: 687–694. doi:10.1016/j.jnutbio.2009.04.002.

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