Research Article

 

 

Temperament during Milking Process and its Effect on Behavioral, Productive Traits and Biochemical Parameters in Friesian Dairy Cows

 

Shereen El. Abdel-Hamid1, Doaa M.Abdel Fattah2, Hanaa Mohamed Ghanem3*, Eman Abd-Allah Manaa4

1Veterinary public health Department, Faculty of Veterinary Medicine, Zagazig University, Egypt; 2Department of biochemistry, Faculty of Veterinary Medicine, Zagazig University, Egypt; 3Department of Animal Husbandry and Wealth Development, Faculty of Veterinary Medicine, Mansoura University, 35516, Egypt; 4Department of Animal Wealth Development, Faulty of Veterinary Medicine, Banha University, El-Kalyobia, Egypt.

 

Editor | Kuldeep Dhama, Indian Veterinary Research Institute, Uttar Pradesh, India.

Received | July 05, 2017; Accepted | August 18, 2017; Published | November 22, 2017

*Correspondence | Hanaa Mohamed Ghanem, Department of Animal Husbandry and Wealth Development, Faculty of Veterinary Medicine, Mansoura University, 35516, Egypt; Email: moody_henno@yahoo.com

Citation | Abdel-Hamid SE, Fattah DMA, Ghanem HM, Manaa EA (2017). Temperament during milking process and its effect on behavioral, productive traits and biochemical parameters in friesian dairy cows. Adv. Anim. Vet. Sci. 5(12): 508-513.

DOI | http://dx.doi.org/10.17582/journal.aavs/2017/5.12.508.513

ISSN (Online) | 2307-8316; ISSN (Print) | 2309-3331

Copyright © 2017 Abdel-Hamid et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

 

INTRODUCTION

 

Cattle are social animals and live in groups, and behave in a manner associated with this way of life as each member of the groups maintains its relationships and communicates between themselves (Charlton et al., 2011). Milk and milk products constituted about 75% from the total income obtained from animals in Egypt and it play a great role in human supplementation with high amount of daily protein intake (Atallah, 2004).

 

There was positive relationship between dairy temperament score and milk production traits in cows. Temperament of the animal is very important especially during the production phase, so any changes during lactation in temperament of cows scored directly before milking is associated with stress and so convert the animals from docile animal to aggressive one (Wanger, 2007). Therefore, any stress affects the temperaments of the animals has a significant ecological and evolutionary role and so make functional interactions and disturbances among several important traits (Von Schantz et al., 1999; Costantini et al., 2008). Stress leads to a number of physiological changes in the body including altered locomotors activity and general exploratory behavior which associated with almost all of the body processes, for example, with reproductive processes (Monaghan et al., 2009). Since under physiological conditions a certain level of free radicals and reactive metabolites is required, complete suppression of this free radical formation which caused by stress would not be beneficial (Halliwell and Gutteridge, 2007).

 

Release of oxytocin as result of teat stimulation is important for fast and complete milk removal (Bruck maierand Blum, 1998). In addition, release of prolactin and cortisol is induced by machine (Goreweitet al., 1992) or suckling (Williams et al., 1993). If the animal has been interrupted before milking, the release of all hormones can be affected, as,lack of oxytocin release and delayed cortisol and augmented prolactin release (Bruck maier et al., 1992), and may reached to inhibited milk ejection after parturition (Bruck maier et al., 1993), which in turn affects on several productive and milk related traits (Silveria et al., 1993).The objectives of the present study were to reveal the effect of temperament on behavioral, productive traits and biochemical parameters (cortisol and prolactin) in Friesian Dairy Cows.

 

MATERIALS AND METHODS

 

This study was reviewed and approved by the Animal Care and Welfare Committee of faculty of veterinary medicine, Zagazig University, Egypt.

 

Experimental Animals and Management

This study was carried out on one hundred Friesian dairy cows aging 3 to 6 years old belonging to private dairy cow’s farm at Hehia city in Sharkeya Governorate during the period between March 2016 to March 2017. The animals were housed free in an open yards, supplied with a cool spraying system during hot climate. Animals had free access to clean water from common water troughs under a shaded area. The animals were fed on total mixed ration according to its production state NRC (2001). The animals were identified by applying an ear tag containing the number of dairy cow and the same number was applied on the side of neck of each animal by using a coloring material.

All cows were machine milked; 3 times a day with eight hours interval. Milking was carried out in a ventilated herringbone-milking parlor, it was connected with electronic digital display to record the milked cow’s number. All data were collected through automatic central computer, which is specialized for dairy farm’s electronic data management. Thirty dairy cows were selected according to their temperament and allocated in the same yard with stocking density 30 m2 / cow.

 

Temperament Score

The cows were classified according to their temperament during milking and the milkier questionnaire into calm (in which the cow indicated docile reaction during teat preparation and during milking process), nervous (restless) (in which cows show frequent movement, foot lifting and tail movement with flicked tail and shift her weight) and aggressive (in which the cows show intensive restlessness during teat preparation, butting and kicking the milker) (Najafi et al., 2009).

 

Data Measurments

Maintenance Activities:

Observation was carried out 3 hours per week (6 minute interval for each cow through one hour observation for each group), by using a focal sample technique (Youssef, 1995). A stopwatch, field notice and photo-graphing camera were used during the observation time. All maintenance activities were recorded as time and frequency by each animal per 12 h observation period.

 

-Ingestive behavior (Eating- Drinking- Rumination) (Phillips, 2002).

-Standing, walking and lying behavior (Fraser and Broom, 1990).

-Eliminative behavior (Defecation and Urination).

- Body care and agonistic behavior (Grooming &Aggression) (Philips,1993).

 

Productive Traits:

- Total milk production: is the actual amount of milk produced by the cow in one lactation.

- Day in milk: is the period from calving to the first breeding.

- Daily milk production: is theactual amount of milk produced by cowper day.

- Morning time: is the time consuming for milking in the morning.

- Evening time: is the time consuming for milking in the evening.

 

Biochemical Parameters:

Cortisol: Stock solutions of cortisol and sample preparation were done according to Kushnir et al. (2004) and Kao et al. (2001).

Prolactin: By Sequential Method Test System Product Code: 4475-300 (Maddox et al., 1991).

 

STATISTICAL ANALYSIS

 

Preliminary test was applied to the percentage data before comparison and analysis and found that data was homogeneous and did not need a transformation to the corresponding arcsine angle. Data were statistically analyzed by SPSS (2013) using General Linear Model (GLM) procedure according to the following model: Yijk = μ + Ti+ eij, where, μ is the overall mean, Ti is the fixed effect of different ages groups and eij is random error. All data are expressed as the Least Square Mean (LSM) ± S.E. Also, the resultants pvalues were also expressed pvalue of < 0.05 was considered to be statistically significant.

 

Table 1: Effect oftemperamenton ingestive and kinetic behaviour of dairy cow.

 

Temperament	Calm	Nervous	Aggressive
Behavior
Eating time	85.66± 7.44a	78.00± 3.46a	73.00± 6.55a
Eating frequency	23.33± 3.52a	22.66± 0.88a	30.33± 4.17a
Drinking time (min)	1.33± 0.33a	0.66± 0.16a	0.83± 0.16a
Drinking frequency	5.00± 0.57a	5.00± 1.15a	2.66± 0.88a
Rumination time (min)	96.66± 12.01a	80.66± 5.20a	62.00± 6.42a
Rumination frequency	21.33± 2.02a	18.66± 3.38a	13.33± 0.88a
Walking time(min)	22.33± 1.45c	77.00± 11.93b	112.00± 9.45a
Walking frequency	48.33± 4.40c	102.67± 3.71b	111.67± 4.40a
Standing time (min)	115.00± 2.88a	140.00± 15.27a	142.33± 16.69a
Standing frequency	23.66± 4.70a	12.66± 1.20b	8.33± 0.88c

Means with different superscripts in each row are significant at (P <0.05).

 

RESULTS

 

Table 1 showed the effect of temperament on ingestive and kinetic behavior of dairy cow, results showed that there were non significant differences between different types of temperament of dairy cow on ingestive behavior although the eating, ruminating times were increased with docile temperament. Table 2 showed the effect of temperament on comfort and resting behavior of dairy cow, as the urination, defecation frequency were increased with aggressive temperament then nervous one and at lowest level with calm temperament. While, resting and sleeping were increased with calm temperament than nervous and aggressive temperament, Grooming increased with calm animal while aggressive increased with nervous ones. Table 3 showed the effect of temperament of dairy cow on some productive traits, results showed that the daily milk, day in milk and total milk production was increased with calm temperament and decreased with nervous and aggressive temperament and the differences were highly significant. On the other hand the milking time either morning or evening milking was prolonged with aggressive temperament which may be affected the time, effort of the employer of the dairy farm.

 

Table 2: Effect oftemperamenton comfort and resting behaviour of dairy cow.

 

Temperament	Calm	Nervous	Aggressive
Behavior
Urination frequency	11.00± 0.57c	22.66± 1.20b	32.66± 3.71a
Defecation frequency	12.33± 1.45c	26.33± 4.33b	35.00± 2.88a
Recumbancy time (min)	80.00± 2.88a	50.00± 5.77b	34.33± 2.96c
Recumbancy frequency	15.66± 0.88a	12.00± 1.52a	13.33± 0.88a
Sleeping time(min)	63.33± 6.00a	25.00± 2.88ab	24.33± 3.48b
Sleeping frequency	17.66± 1.45a	12.00± 0.57b	8.66± 0.88c
Grooming frequency	36.00± 2.08a	27.33± 0.88b	22.66± 0.88c
Aggression frequency	8.33± 0.88b	15.00± 2.88ab	24.00± 5.03a

Means with different superscripts in each row are significant at (P <0.05)

 

Table 3: Effect of temperament of dairy cow on some productive performance.

 

Temperament	Calm	Nervous	Aggressive	P value
Traits
Daily milk (kg)	39.64± 0.60a	28.81± 0.76b	21.07± 0.80c	**
Day in milk (days)	335.78± 39.76a	187.33± 7.93b	141.33± 39.76c	**
Total milk production(kg)	1779.60± 358.69a	591.39± 12.79b	385.98± 21.44c	**
Morning time	4.41± 0.22a	6.70± 0.29b	9.71± 0.36c	**
Evening time	3.95± 0.22a	5.84± 0.27b	8.98± 0.38c	**

 

Means of different ages within the same row having different superscripts are significantly different (p ≤ 0.05).

 

Table 4 showed the effect of temperament of dairy cow on biochemical parameters, results showed that significant differences between aggressive, nervous, calm cows in relation to cortisol and prolactin level due to the correlation between cortisol and prolactin release. It was founded that the level of cortisol in first stage of experiment was significantly increased in aggressive cows than calm and nervous cows, while the level of cortisol in second time of experiment calm cows were significantly increased than aggressive and nervous cows. Our results showed that third time cortisol level significantly increased in aggressive than nervous and calm cows. On other hand the prolactin level in first time was significantly increased with aggressive and nervous cows than calm cows, while in second time calm and nervous cows were significantly increased than aggressive cows, but in third time prolactin was significantly increased in nervous cows than aggressive and calm cows.

 

Table 4: Effect of temperament of dairy cow on some biochemical parameters.

 

Temperament	Calm	Nervous	Aggressive	P value
Traits
First time cortisol	1.32c ±0.58	2.20b±0.05	2.53a ±0.06
Second time cortisol	3.12a ±0.58	2.24c ±0.01	3.04b ±0.01
Third time cortisol	1.14b ±0.58	1.11c ±0.05	1.28a ±0. 05
First stage prolactin	0.55b ±0.15	0.66a ±0.01	0.63a ±0.05
second stage prolactin	0.62a ±0.08	0.62a ±0.05	0.50b ±0.05
Third stage prolactin	0.73b ±0.58	0.77a ±0.05	0.65c ±0.05

 

Means of different ages within the same row having different superscripts are significantly different (p ≤ 0.05).

 

DISCUSSION

 

Non significant differences were found between different types of temperament of dairy cow on ingestive behavior although the eating, ruminating times were increased with docile temperament. These results were similar to (Langbein and Raasch, 2000) who stated that calm high yield dairy cow required more time for feeding and rumination while walking and standing time were increased with nervous and aggressiveness. Phillips, (2002), Ceballos and Weary, (2002); and Fukasawa and Tsukad, (2010), stated that walking, exploring and licking object were increased with aggressive animal in order to evaluate stressful conditions. In contrast (Cavallina et al., 2008; Tripaldi et al., 2004; Stafford and Gregory, 2008) stated that when agonistic behavior increased with stress caused by mechanical milking the time of locomtion decreased. Regarding urination, defecation frequency, it was increased with aggressive temperament then nervous one and at lowest level with calm temperament. Similar results with (Horning and Kramer, 2003) mentioned that nervous cattle defecate more and produce more liquid faces as an indication of more stress. While, resting and sleeping were increased with calm temperament than nervous and aggressive temperament (Munksgaard et al.,1999; Cavallina et al., 2008).Grooming increased with calm animal while aggressive increased with nervous ones (Von keyserligk et al., 2008)

 

Concerning the productive performance of dairy cows in relation to their temperament during preparation for milking and actual milking process, results showed that the daily milk, day in milk and total milk production were increased with calm temperament and decreased with nervous and aggressive temperament and the differences were highly significant. The obtained results were in agreement with (Devyatkina, 1986) who revealed linear relationship stands between temperament score and daily and total milk yields, but the relationship with lactation length was not clear. Furthermore (Roy and Nagpoul, 1986), found that in Bos indicus cows with unfavorable temperament produced less milk and their ability of releasing milk was the worst compared to cows having better temperament and suggested that milk yield significantly decreased with nervousness and aggressiveness. As well as, docile temperament had more milk producer than nervous and aggressive temperament even with the same breed and the same management (Youssef and Fouda, 1995). In contrast (Munkgaard et al., 2001) found that temperament of cow had no effect on milk yield. Furthermore, (Szentleleki, 2008) did not reveal any correlation between milk production and temperament and suggested No correlation was found between daily milk yield and temperament score.

 

Regarding to the effect of temperament of dairy cow on biochemical parameters, results showed that there were significant differences between aggressive, nervous, calm cows in relation to cortisol level and prolactin due to the correlation between cortisol and prolactin release.

These results were in agreement with (Silveria et al., 1993) who reported that the first suckling of dairy cows after four weeks of only machine milking caused a lack of oxytocin release. The effect is more variable according to the temperament of cows. The possible relationship of dairy temperament induced lack of oxytocin release to maternal bond. Also prolactin release was inhibited during suckling by alien calves (Perez et al., 1985). In suckling management system, oxytocin and prolactin release in ewes are not under the similar central regulation (Marnet and Negreo, 2000). Stress can be defined as a process of altered biochemical homeostasis produced by psychological, physiological, or environmental stressors (Dimitrios et al., 2003). There is evidence that under physiological conditions the endogenous opoids have atonic effect on oxytocin release which suppress cortisol and stimulate prolactin (Schams et al., 1998). The milking temperament can be considered as a kind of emotional response resulting in increase of beta-endorphine (Bishop et al., 1999). Probably the endogenous opoid system could play some role in the release of measured hormones in first suckling of the cows conditioned to machine milking (Bruckmaier and Blum, 1998).

 

SUMMARY

 

Based upon these results, it is concluded that temperament test application is positive benefits for dairy cattle breeders, e.g. calm animals can produce more productive and behavioral performance. As the maintenance behavior and productive performance of female dairy cows were changed according to their temperament during milking and so we should keep the temperament of the animal. So it was recommended that, the cows which are nervous and aggressive with frequent tail movement and kicking during milking process should be milked separately from normal calm cows to not altered their behavior and affect their milking process then its production and consequently the income.

 

ACKNOWLEDGEMENTS

 

We are grateful to all staff of the dairy farm which locates at Hehia city at Sharkiya governorate, Egypt, for supplying us with all the information expressed temperment and cow’s milk production.

 

CONFLICT OF INTEREST

 

The authors have declared that no competing interest exists.

 

AUTHORS CONTRIBUTION

 

SE. Abdel-Hamid conceived and designed the experiments; HM Ghanem and EA. Manaa performed the productive part of experiments, wrote the manuscript and analyzed the data, DM. Abdel Fattah analysed the biochemical parameters.

 

REFERENCES

 

• Atalla ST (2004). Effect of cattle diseases on reproduction, production and economic efficiency of dairy farms. Minufeia Vet. J. 3(1): 99-114.

• Bishop JD, Malven PV, Singleton Wl., Weesner GD (1999). Hormonal and behavioral correlates of emotional states in sexually trained boars. J. Anim., Sci. 77: 3339-3345. https://doi.org/10.2527/1999.77123339x

• Bruckmaier RM, Blum JW (1998). Oxytocin release and milk removal in ruminants’ .J. Dairy Sci. 81: 930-949. https://doi.org/10.3168/jds.S0022-0302(98)75654-1

• Bruckmaier RM, Schams D, Blum JW (1992). Etiology of disturbed milk ejection in parturient primiparous cows. J. Dairy Res. 59: 479-489. https://doi.org/10.1017/S002202990002714X

• Bruckmaier RM, Schams D, Blum JW (1993). Milk removal in familiar and unfamiliar surroundings: concentration of oxytocin, prolactin, cortisol, and B-endorphin. J. Dairy Sci. 60: 449-456. https://doi.org/10.1017/S0022029900027813

• Cavallina R, Roncoroni C, Campagna NC, Canali E (2008). Buffaloe behavioral response to machine milking in early lactation. Ital. Anim. Sci. 7: 287-295. https://doi.org/10.4081/ijas.2008.287

• Ceballos A, Weary DM (2002). Feeding small quantities of grain in the parlour facilities pre-milking handling of dairy cows: anote. Appl. Anim. Behav. Sci. 77: 249-254. https://doi.org/10.1016/S0168-1591(02)00054-0

• Charlton GL, Rutter SM, East M, Sinclair LA (2011). Preference of dairy cows: indoor cubicle housing with acess to atotal mixed ration vs. access to pasture. Appl. Anim. Behav. Sci. 130: 1-9. https://doi.org/10.1016/j.applanim.2010.11.018

• Costantini D (2008). “Oxidative stress in ecology and evolution: lessons from avian studies,” Ecology Letters. 11(11): 1238–1251. https://doi.org/10.1111/j.1461-0248.2008.01246.x

• Devyatkina GS (1986). Selection of cows for stress resistance. Zhinvontnovodsto. 9: 40-41.

• Dimitrios, NT, Geogrios KC, Dmitrios IXH (2003). “Neurohormonal hypothesis in heart failure,” Hellenic J. Cardiol. 44(3): 195–205.. View at Google Scholar • View at Scopus.

• Fraser AF, Broorn DM (1990). Farm animal behavior and welfare. Third edition. Pp 137-138.

• Fukasawa M, Tsukada H (2010). Relationship between milk cortisol concentration and the behavioral characteristics of postpartum cows introduced to a new group. Anim. Sci. J. 81: 612–617. https://doi.org/10.1111/j.1740-0929.2010.00770.x

• Gorewit RC, Svennersten K, Butler WR, Uvnäs-Moberg K (1992). Endocrine responses in cows milked by hand and machine. J. Dairy Sci. 75: 443-448. https://doi.org/10.3168/jds.S0022-0302(92)77780-7

• Halliwell JM, C Gutteridge (2007). Free Radicals in Biology and Medicine, Oxford University Press, Oxford, UK, 3rd edition.

• Horning B, Kramer C (2003). Behavior of dairy cows in the laying area of three loose housing systems. In: Ferrante, V.; Canali, E.; Mattiello, S.; Minero, M.; Pslestrinei, C.; Tosi M.V.and Verga, M. (Eds). Proc. Int. Soc. Appl. Etho. Italy. 24-28th June, p. 210.

• Kushnir MM, Neilson R, Roberts WL, Rockwood AL (2004). Cortisol and cortisone analysis in serum and plasma by atmospheric pressure photoionization tandem mass spectrometry. Clin. Biochem. 37(5): 357–362. https://doi.org/10.1016/j.clinbiochem.2004.01.005

• Kao PC, Machacek DA, Magera MJ, Lacey JM, Rinaldo P (2001). Diagnosis of adrenal cortical dysfunction by liquid chromatography-tandem mass spectrometry. Annals Clin. Laborat. Sci. 31(2): 199–204.

• Langbein J, Raasch ML (2000). Investigations on the hiding behavior of calves at pasture, ArchivfurTierzucht-Achives if animal breeding. 43: 203-210.

• Maddox PR, Jones DL, Mansel RE (1991). Acta Endocrinol. 125: 621

• Marnet, Negreo (2000). The effect of a mixed management system on the release of oxytocin, prolactin and cortisol in ewes during suckling and machine milking. Reprod. Nutr. Dev. 40: 271-281. https://doi.org/10.1051/rnd:2000131

• Monaghan P, Metcalfe NB, Torres R (2009). “Oxidative stress as a mediator of life history trade-offs: mechanisms, measurements and interpretation,” Ecology Letters. 12(1): 75–92. https://doi.org/10.1111/j.1461-0248.2008.01258.x

• Munksgaard L, Ingvartsen KL, Pedersen LJ, Nielsen VKM (1999): Deprivation of lying dawn affects behavioural and pituitary- adrenal axis responses in young bulls. Acta Agric. Scandinavica Section A- Anim. Sci. 49:172-178.

• Munksgaard L, Passille AM, Rushen J, Herskin MS, Kristensed AM (2001). Dairy cows fear of people: social learning, milk yield and behavior at milking. Appl. Anim. Behav. Sci. https://doi.org/10.1016/S0168-1591(01)00119-8

• Najafi M, Mortazavi SA, Koocheki A, Khorami J, Rokik B (2009). Fat and protein contents, acidity and somatic cell counts in bulk milk of Holstein cows in the khorasan rozavi province, Iran. Int. J. Dairy Technol. 62:19-26. https://doi.org/10.1111/j.1471-0307.2008.00451.x

• NRC (National Research Council) (2001). Nutrient requirements of dairy cattle. National Academy Press. Washington, D. C.

• Perez O, Jimenez De Perez N, Poindron P, Le Neindre P, Ravault JP (1985). Mother- young relations prolactin response to mammary stimulation in cows: influence of milking and free or fettered suckling. Reprod. Nutr. Dev. 25: 605- 618. https://doi.org/10.1051/rnd:19850502

• Phillips CJC (1993). Cattle behavior farming press, wharfedale road, Ipswich, IPI4LG. UK. Pp 68-74.

• Phillips CJC (2002). Cattle behavior and welfare, 2nd ed. BlackWell. Science Ltd., Oxford. https://doi.org/10.1002/9780470752418

• Roy PK, Nagpoul PK (1986). The influence of gentic and milking parameters in dairy animals. Indian J. Anim. Prod. Manage.. 2:11-15.

• Schams D, Tancin V, Kraetsl W (1998). The effect of morphine and naloxone on the release of oxytocin, cortisol and prolactin and on milk ejection in dairy cows. J.Anim. Sci . 76(Suppl . 1). J. Dairy Sci. 81(Suppl 1), 213.

• Silveira PA, Spoon RA, Rayan DP, Williams GL (1993). Evidence for maternal behavior as a requisite link in suckling –mediated an ovulation in cows. Biol. Reprod. 49: 1338 -1346. https://doi.org/10.1095/biolreprod49.6.1338

• SPSS (2013). IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp.

• Stafford KJ, Gregory NG (2008). Implications of intensification of pastroral animal production of animal welfare. J. Newzeol Vet. 56: 74-280.

• Szentleki A, Zengo G, Szentleki K, Keke K, Tozser J (2008). Behavior of Holstien friesian cows during conventional milking. Allattenyesztes esTakarmanyozas. 57(4): 315-326.

• Tripaldi C, De Rosa G, Grasso F, Napalitano F (2004). Housing system and welfare of buffaloe cow. J. Anim. Sci. 68: 477-483.

• Von Keyserlingk MAG, Olenick D, Weary DM (2008). Acute behavioral effects of regrouping dairy cows. J. Dairy Sci. 91: 1011–1016. https://doi.org/10.3168/jds.2007-0532

• Von Schantz T, Bensch S, Grahn M, Hasselquist D, Wittzell H (1999). “Good genes, oxidative stress and condition-dependent sexual signals,” Proceedings of the Royal Society B. 266 (1414): 1–12. https://doi.org/10.1098/rspb.1999.0597

• Wanger S (2007). Understanding bovine behavior for safe handling proceeding of the fortieth annual conference, American association of bovine practitioners, Vancouver, british Columbia, Canada, 20-22 September. 207-208.

• Williams GL, McVey WR, Hunter JF (1993). Mammary somatosensory pathways are not required for suckling–mediated inhibition of luteinizing hormones secretion and delay of ovulation in cows. Biol. Reprod. 49: 1328-1337. https://doi.org/10.1095/biolreprod49.6.1328

• Youssef MYI (1995). Behavioral factors affecting calves and sheep performance. Ph. D., Thesis. Facult. Vet. Med. Zagazig University. Egypt.

• Youssef MYI, Fouda MM (1995). The effect of temperament of friesian cows on milking ability. Alex. J. Vet. Sci. 2: 147-150.