ReseaRch PaPeR Journal of Agricultural and Marine Sciences Vol. 21 (1): 2-7 DOI: http://dx.doi.org/10.24200/jams.vol21iss0pp1-6 Received 15 Sep 2014 Accepted 08 Nov 2015 Genetic and environmental factors affecting 305-day mature equivalent milk yield of Holstein Friesian cows in the United Arab Emirates Mohamed ElNour ElBoshra1, Tagelsir Eisa Ali2* and Ali Ahmed Hassabo3 العوامل الوراثية والبيئية اليت تؤثر على إنتاجية احلليب من أبقار اهلولستاين فريزاين يف دولة اإلمارات العربية املتحدة حممد النور البشرى1, تاج السر عيسى علي2 وأمحد علي حسابو3 Abstract. The main objective of this research was determining the effect of sire of cow, year and season of freshening, lactation number, and their different interactions on 305-day mature equivalent (ME) milk yield of Holstein Friesian cows in the United Arab Emirates (UAE). It also aimed to estimate sire and error variance and heritability of 305-day ME milk yield. The data was collected from AL Salamat Dairy Farm in Al Ain. The average size of the herd was 1000 animals during the experimental period. The Dairy Comp 305 computer program was used for compiling the data. The data under the study covered the years 2004 to 2007. The climatic temperature during the summer (April to September) varied from moderate to very hot. The winter (October to March) had lower temperature and higher relative humidity than the summer. All the effects were fixed except for random sire and residual error term. The overall least-square mean of the 305-day ME milk yield was 11060±355 kg/305 days. The data showed a significant effect of sire of cow (p≤0.001), year of freshening (p≤0.001), lactation number (p≤0.01), year x season of freshening (p≤0.01), and year of freshening x lactation number (p≤0.001) on milk yield. However, the effect of season of freshening showed non signif- icant effect. No significant seasonal differences were found in 2004. However, in the year 2005 and 2006, the summer fresheners had significantly higher yield than those of the winter season. The 305-day ME pertaining to summer vs. win- ter were 11691±400 kg vs. 11483±410 kg and 11522±369 kg vs. 11041±374 kg for the year 2005 and 2006, respectively. However, the reverse was true in 2007 with the fresheners during summer that have lower 305-day ME (10286±372kg) than those freshening during winter (10672±388 kg). The differences among the three lactations were relatively high in 2004 (9837 to 12116 kg), compared to 2005 - 2006 (11267 to 11747 kg) and 2007 (9853 to 11355 kg). The heritability of 305-day ME was 0.31 indicating that a significant response to selection would be achieved through a well-designed progeny testing and cow evaluation program. املســتخلص:كان اهلــدف األول مــن هــذا البحــث هــو دراســة تأثــر األب وســنة اإلنتــاج وموســم اإلنتــاج ورقــم الــوالدة والعالقــة فيمــا بــن هــذه العوامــل علــى اإلنتاجيــة الســنوية للحليــب )إنتــاج احلليــب املعــدل لــر305 يــوم( يف أبقــار اهلولســتاين فريزيــان بدولــة اإلمــارات العربيــة املتحــدة. أمــا اهلــدف الثــاين فــكان حســاب معامــل التوريــث بعــد حتديــد مقــدار التبايــن لــأب وللخطــأ العشــوائي. مت مجــع بيانــات هــذا البحــث مــن مزرعــة ســيح الســالمات يف مدينــة العــن بدولــة اإلمــارات العربيــة املتحــدة. كان متوســط حجــم القطيــع خــالل ســنوات الدراســة )2004-2007م( هــو 1000 رأس مــن األبقــار. مت إســتخدام برنامــج الديــري كومــب )2000( لتجميــع هــذه البيانــات وحتريرهــا. تباينــت درجــات احلــرارة خــالل فــرة الصيــف )أبريــل إىل ســبتمرب( مــن متوســطة إىل عاليــة مــع درجــات رطوبــة عاليــة أيضــاً. ويف فــرة الشــتاء )أكتوبــر إىل مــارس( تنخفــض درجــات احلــرارة وتزيــد الرطوبــة النســبية بدرجــة كبــرة مقارنــة بفصــل الصيــف. مت إســتخدام برنامــج هــاريف للمربعــات الصغــرى واإلحتمــاالت الكــربي للتحليــل اإلحصائــي. حــوت املعادلــة اإلحصائيــة لتحليــل إنتاجية احلليب على أب البقرة ورقم الوالدة وســنة اإلنتاج وموســم اإلنتاج والتفاعل بن ســنة اإلنتاج وموســم اإلنتاج كان بن ســنة اإلنتاج ورقم الوالدة باإلضافــة إىل اخلطــأ العشــوائي. كان تأثــر مجيــع العوامــل ثابتــاً مــا عــدا تأثــر األب واخلطــأ العشــوائي فــان تأثرمهــا عشــوائياً. كان املتوســط العــام إلنتاجيــة احلليب 11060±355كجم. كان تأثر األب )p>001( وســنة اإلنتاج )p>001( ورقم الوالدة )p>001( والتفاعل بن ســنة اإلنتاج وموســم اإلنتــاج )p>0,01(, وكذلــك ســنة اإلنتــاج ورقــم الــوالدة )P>0,01( دااًل معنويــاً علــى إنتاجيــة احلليــب الســنوية للبقــرة بينمــا كان تأثــر موســم اإلنتــاج غــر دال معنويًــا علــى تلــك الصفــة اإلنتاجيــة اهلامــة. مل يكــن هنــاك تأثــر ملوســم اإلنتــاج يف ســنة 2004. ولكــن عنــد دراســة الســنوات 2005 و 2006 وجــد أن إنتاجيــة البقــرة يف فصــل الصيــف كانــت أعلــى منهــا يف فصــل الشــتاء. وبنــاءاً علــى ذلــك وجــد أن متوســط إنتاجيــة البقــرة يف هذيــن املومســن )الصيــف مقابــل الشــتاء( هــو 11691±400 كجــم مقابــل 11483±410 كجــم و11522±369 كجــم مقابــل 11041±374 كجــم للســنوات 2005 و 2006 علــى التــوايل. ولكــن العكــس كان صحيحــاً يف عــام 2007 حيــث وجــد أن األبقــار الــي بــدأت موســم إنتاجهــا يف فصــل الصيــف لديهــا أقــل إنتاجيــة )10286±372 كجــم( مــن مثيالهتــا الــي بــدأت مومسهــا يف فصــل الشــتاء )10672±388 كجــم (. كانــت الفروقــات بــن الــوالدات كبــرة نوعــاً مــا يف عــام 2004 )تراوحــت مــن 9837 إىل 12116كجــم(, وصغــرة يف عامــي 2005 و 2006 )تراوحــت مــن 11267 إىل 12747كجــم( ومتوســطة يف عــام 2007 )تراوحــت مــن 9853 إىل 11355كجــم(. كان معامــل التوريــث هــو 0,31 ممــا يــدل علــى أن هنالــك فرصــة كبــرة للتحســن الوراثــي مــن خــالل برنامــج إختبــار النســل الذائــع الصيــت. الكلمات املفتاحية: دولة اإلمارات العربية املتحدة ، أبقار حليب ، هولستاين فريزيان، انتاج احلليب ، البيئة 1 AlAin Dairy Farm, AlSalamat dairy farm, AlAin, UAE. 2* Tagelsir Eisa Ali ( )Dept of Presidents’ Affairs AlAin, MNC, AlAin,UAE. email: tagali@hotmail.com 3AlNileen University, Faculty of Agriculture science, Khartoum, Sudan. 3Research Article ELboshra, Ali and Hassabo Introduction There is an increasing demand of animal products in all countries around the world. However these demands exert more pressure on the countries in the arid zone to increase the animal production (Phil- ip, 2010). It is well-known that the indigenous cattle are low-producing animals. Thus, almost all the countries in the tropics and sub-tropics have imported high milk producing cattle from temperate zone. The dairy cattle such as Friesian and Holstein-Friesian are the most com- monly imported cattle. AL Ain Dairy Farm is a leading dairy company in UAE. Several problems have been en- countered in raising these animals in the tropics. Heat stress was one of the most important problem (Yousef, 1985). Furthermore, Yousef (1985) defined heat stress as the magnitude of forces external to the body system which tend to displace its system from their resting or ground state. Climate is a combination of elements that include temperature, humidity, rainfall, air movement, radiation, barometric pressure, and ionization (John- son, 1987). The relationship between the animal and en- vironment determines the degree to which the animal remains in thermal equilibrium with its environment (Finch, 1976). Effects of heat stress are more severe in hot humid climates, but dairy cattle raised in areas with relatively moderate climates are also exposed to periods of heat burden. So the thermal environment is a major factor that affects milk production and reproductive performance of dairy cows especially in animals with high genetic merit (Koppock et al,1982). Dairy cattle research tended to concentrate on genet- ic improvements in order to increase milk production. Little attention had been paid to the thermoregulatory ability of the modern cow, as her capacity to produce milk (Murphy et al. 1983). Tao and Dah (2013) reported that cows which were heat stressed during late gestation have impaired mammary growth before parturition and decreased milk production in the subsequent lactation. Ray (1992) found that milk production was depressed for cows calving in summer and fall. Heat stress threat- ens the normal metabolic balance and usually produces positive feedback, which affects the performance of the animal when the heat exceeds the upper critical tem- perature (UCT). High producing cows are affected more than low pro- ducing and dry cows as the thermonuteral zone (TNZ) shifted down as milk production, feed intake, and heat production increased (Koppock et al, 1982). Johnson et al. (1963) showed that cows consumed less feed as am- bient temperature and combined ambient temperature and percent relative humidity (RH) were increased. Ber- man et al. (1985) suggested that the upper limit of am- bient temperatures at which Holstein cattle may main- tain a stable body temperature was 25 to 26°C, and that above 26°C, practices should be instituted to minimize the rise in body temperature. However, in the humid area, one of the major challenges is the combined effects of high RH with high ambient temperature. When the temperature reaches 29°C with 40% RH the milk yield of Holstein, Jersey and Brown Swiss cows was 97%, 93%, and 98% of the normal yield, respectively. But when the RH was increased to 90%, the yields of these breeds de- creased to 69%, 75%, and 83% of the normal values, re- spectively (Binaca, 1965). Knowledge of other non-genetic factors that influ- ence production is important for better assessment of genetic ability of dairy farm. Knowledge of the inter- action between genetics and environment is also very important for successful selection and progeny testing programs. Moreover increased milk production can be achieved by implementation of environmental modifi- cation such as installation of cooling facilities through shades, water spray, and fans (Armstrong 1994). Fur- thermore, Armstrong (1994) stated that the economic benefit should be determined before installing these equipments to reduce heat stress. A point to mention is that environmental modifications can not only be used to protect the animals, but they can also be used to pro- tect dairy products from deterioration of their quality. Intawiwat et al. (2013) developed green polyethylene film for protection of dairy products to reduce degra- dation of photosensitizers. Beede and Collier (1986) and Chase (2005) identified three management strategies to minimize the effects of heat stress: physical modification of the environment (shading and cooling), genetic de- velopment of heat-tolerant breeds and improved nutri- tional management practices. For accurate selection of bull and better evaluation of dairy farms, 305-day ME milk yield was used. The 305-day ME milk yield is the standardized milk yield according to some factors. The most important factors in this standardization are lactation length, calving age and milking frequency (Suleyman, 2006). Standardizing records according to these factors will raise accuracy in selection as they reflect the genetic structure of animals. This method is also important for proper evaluation of strength of the cow in milk production as well as estima- tion of the excepted of subsequent lactations yield (Su- leyman, 2006). While superior bulls or cows are being selected for breeding, their ability to transfer this genetic merit to their progeny should be considered by breeders. In simple terms heritability (h2) measures the degree to which the phenotypic value of an individual reflects the actual genetic merits of that individual. This study focuses on the performance of the Holstein Friesian cows in the United Arab Emirates with the fol- lowing specific objectives: 1-To determine the effect of sire of cow, lactation number, year of freshening, season of freshening, and year X season of freshening, and year of freshening X lactation interaction on 305-day ME milk yield of the Holstein Friesian cows in UAE. 2-To estimate heritability of 305-day ME milk yield 4 SQU Journal of Agricultural and Marine Sciences, 2016, Volume 21, Issue 1 Genetic and environmental factors affecting milk yield of Holstein Friesian cows in the United Arab Emirates using sire and residual variance components for Hol- stein Friesian in UAE. Materials and methods Area of study and climate This study was conducted in Sei’h AL Salamat Dairy Farm which is one of AL Ain Farms for Livestock and Animal Production. It is located in Al Ain city, found in the eastern part of UAE. This farm was initially estab- lished in 1987 with 300 milking cows. Now the farm has 1000 milking cows and 750 rearing heifers for replace- ment. The latitude at Sei’h AL Salamat Dairy Farm area is 24°12’N and the longitude is 55°46’ E. The ambient tem- perature, relative humidity and rainfall were taken from AL Ain Weather Station, located in the same farm area. Climatic condition in the UAE is generally hot and hu- mid during April to September and warm to cool from October to March. The RH throughout the year is high in the coastal area and decreases gradually toward the interior region. Al Ain city is about 200 km away from the costal area, so it is less humid than the costal area. The maximum temperature during the period of study gradually increased from 26.6º C in January and reached the peak of approximately 44.0º C during the period from June to August and then declined gradually to reach 27.2º C in December. On the other hand the max- imum RH started with a peak of 93% in January and de- clined to the lowest value; of approximately 62%; during May to August, then gradually increased to reach 91% in December. These results indicated that the months with high maximum temperature has low RH and this was very important and helpful in the use of evaporative cooling system. Similar tendency were observed with the minimum monthly temperature and RH months. Management system According to the routine management based on person- al communication with the farm managers, the breed of cattle studied was Holstein Friesian. The sheds were free-stall and each was 72x63 meters in dimension and accommodated 125 cows. The shaded area was 15.5% of the total area of the shed. The space between adjacent sheds was 4.5 meters wide and it was roofed and used as feeding area. All the cows’ standing and feeding area were covered with concrete. The sheds were equipped with fans, sprinkles and Korral Kool system (American Cooling System using sprinkles and fans controlled by a computer). During the years of the study (2004-2007), all the different groups of cows were covered with the cool- ing system. Cow shower was fixed at the exit of milking parlor. The cows were fed total mixed ration (TMR) which was formulated in the farm according to the need of the different cow groups. The cows were milked four times a day. The daily milk yield per cow was measured two times a month. Drinking water was available on a 24- hour basis, providing eight inch as water space per cow. Intensive management practices were implemented in order to counteract the heat stress. Dairy Comp 305 program (Valley Agricultural Software, 2000) was used for cow management. The program monitored milk pro- duction, conception rate, pregnancy rate, culling rate and ME milk yield calculation. Animal health and vaccination Based on the personal communication with the veter- inarian in charge, the program of treatment and vacci- nation against infectious disease (e.g. Foot and Mouth Disease, Rinder Pest, Clostridium, Brucela, Rota Virus, Corona Virus and E coli) was designed and applied by qualified staff. Sick animals were isolated and treated. The application of preventive measurement was started at the gate of the farm by good bio-security and foot and wheel bath. The cow sheds were cleaned three to four times daily. The flies and insects were controlled by AL Ain Municipality. Samples specimens were sent to the laboratory for investigation when necessary. The farm received feedback report from the milk factory showing the composition analysis and microbiology counting of total Bacteria and Coli-form for the farm raw milk on daily basis. Corrective action was taken if necessary. Data collection The data for the current study were collected from Se’h Al Salmat Dairy Farm, during the years 2004 to 2007 in- clusive. Cow milk record consisted of cow identification Table 1. Distribution of ME yield records by year x season of freshening subclass1. Year of Freshening Season of Freshening Total Summer Winter 2004 47 57 104 2005 110 107 217 2006 227 166 393 2007 323 114 437 Total Records 707 444 1151 1ME: 305-days mature equivalent 5Research Article ELboshra, Ali and Hassabo number (ID), sire ID, dam ID, cow date of birth, cow date of calving, cow lactation number, days open, ME milk yield and days in milk. The data were thoroughly edited and records with missing information were discarded. The total numbers of cow records which were used to de- termine the genetic and environmental factors affecting 305-day ME milk yield as well as to estimate heritability for this economically important trait were 1151 record distributed by year and season of freshening (Table 1). Statistical analysis The statistical model which was used to analyze the 305- day ME milk yield data is presented as follows: Yijklm=µ + si + aj + bk + cl + abjK + acjl + eijklm Where Yijklm = ijklm th ME milk yield/cow. µ = fixed mean constant to all observation. si = effect of i th sire of cow for i =1 to 50 (random) aj = effect of j th year of freshening group for j = 2004 to 2007 (fixed) bk = effect of k th season of freshening group for k = 1 for summer and 2 for winter (fixed) cl = effect of l th lactation number for l = 1 to 3 (fixed) abjk = effect of jk th year X season of freshening inter- action (fixed) acjl = effect of jl th year of freshening X lactation num- ber interaction (fixed) eijklm = effect of ijklm th residual error term (random). First, conventional analysis of variance was carried out with all the factors assumed to be fixed except for the random residual error term. Then, Harvey Least square and Maximum Likelihood Computer Program (1988) was used to fit this model (model 2) and also to estimate the sire (σs²) and error (σe²) variance components. For the variance component estimation, the sire of cow and residual error variance term were assumed to be random and have the following distribution N~ (0, σs²) and N~ (0, σe²), respectively. The sires were un-related and errors un-correlated. The heritability (h²) of 305-day ME milk yield was es- timated as follows: h² = 4 σs²/ (σs²+ σe²) Results Factors affecting 305-day ME milking yield Results in Table 2 show that the effects of sire of cow (P ≤ 0.001), year of production (P ≤ 0.001) and lactation num- ber (P ≤ 0.01) were significantly affecting ME milk yield. Furthermore, the effects year X season of freshening (P ≤ 0.01) and year of freshening X lactation number (P ≤ 0.001) interactions were also highly significant. Howev- er, the effect of season of freshening had non significant (P > 0.05) effect. Since the interactions had significant effect on ME mild yield, then the main effect of the in- dividual factors has little value and will not receive any further discussion. The least-square means for the effect of year X season of freshening and year of freshening x lactation number interactions were also depicted on fig- ures 1 and 2 respectively. Heritability of 305-day ME Milk Yield The heritability of milk yield measures the portion of the genetic merit that is transferred from the parent to their progeny. In the present study, a sire model was used and maximum likelihood method was utilized to estimate sire and error variance components. The result in Table 3 shows that the heritability for ME Mature Equivalent milk yield was 0.31. Table 2. Analysis of variance for 305-day ME milk yield¹. Source d.f. Sum of Square Mean squares P-value Sire of cow 49 331659687 6768565 *** Year of freshening 3 112576245 37525415 *** Season of freshening 1 800652 800652 NS Lactation number 2 25277098 12638549 ** Year X Season 3 32795915 10931972 ** Year X Lactation 6 116558474 19426412 *** Residual error 1086 2968086550 2733045 1*P ≤ 0.05, **P≤ 0.01 ***P≤ 0001, NS=Not significant Table 3. Estimation of variance components and heritability of 305d ME milk yield1. Source Value Sire Variance ( σs² ) 230137 Residual Variance ( σe² ) 2733045 Heritability (h² ) 0.31 1h² = (4 σs²/ σs²+ σe²) 6 SQU Journal of Agricultural and Marine Sciences, 2016, Volume 21, Issue 1 Genetic and environmental factors affecting milk yield of Holstein Friesian cows in the United Arab Emirates Discussion Results indicated that the effects of year of freshen- ing (P ≤ 0.001) and lactation number(P ≤ 0.01) on 305- day ME milk yield were highly significant. This finding is close to that of Suleyman (2009) who used the same Least-square method to analyze milk yield of Holstein cows in Turkey. The interaction of year X season of fresh- ening on 305 day-ME milk yield was highly significant (P ≤ 0.01). Similar results were also reported by Ray et.al. (1992). The results in Figure 1 show that during the years 2004 the difference between 305-day ME milk yield of summer and winter calving was insignificant. However, during the years 2005 (11691±400 kg vs. 11483±410 kg) and 2006 (11522±369 kg vs.11041±374 kg) cow freshen- ing during the summer season gave significantly higher average ME milk yield than those freshening during the winter season. However, in the year 2007 those freshening during the summer season gave significantly lower 305-day ME milk yield (10286±372  kg) than their winter counter- parts (10672 ±388  kg). The superiority of the summer freshening over the winter freshening during the years 2005 and 2006, occurred as a result of provision of the efficient cow cooling system. On the other hand the in- feriority of the summer freshening in the year 2007 was due to the increase of the numbers of cows without a parallel increase in the cow cooling system a fact that rendered the cooling system inefficient. These results are in agreement with Ray et al. (1992) who reported that in the absence of efficient cooling system, the summer season had significantly lowered 305-days ME milk yield (7387± 193  kg) than the winter season (7765± 193  kg) in Arizona. As it was mentioned above, the effect of year of fresh- ening x lactation number interaction on 305-days ME milk yield was highly significant (P ≤ 0.001). This inter- action is evident in Fig. 2 where the difference among lactation fluctuated with years of freshening. The largest difference observed among lactations in the year 2004, 2005, 2006 and 2007 was 2279, 449, 122 and 1502 kg, re- spectively. The change of differences among lactations, with increasing years might indicate unavoidable man- agement differences from one year to another. Another reason of year of freshening x lactation number inter- action was the change in ranking of the lactations with years of freshening. A point to mention is that the sec- ond-parity cows had the highest 305-days ME milk yield in the year 2004 (12116±453 kg) while the first lactation cows had the highest 305 day ME milk yield in the years 2007 (11355±407 kg). Another point to mention is that the third-parity cows had the lowest 305-day ME yield throughout the years 2004 to 2007. The heritability of 305-day ME milk yield was 0.31. This result is close to the value of 0.29 which was report- ed by Ojango and Pollott (2001) in Kenya. Estimates of heritability for milk yield from European breeds kept in the tropics were lower than those from similar breeds kept in temperate countries (Lobo et al., 2000). The farm under study imports semen of high quality progeny test- ed breeding bulls. But a heritability of this magnitude suggests that a successful sire evaluation program could be established. Conclusion and recommendations The least-square mean of 305-day ME milk yield for Holstein Friesian cows was 11060 ±355 kg /305 days/ cow. The effect of genetic (sire of cow) and non genetic interacting factors (year and season of production and lactation number) had significantly affected ME milk yield. The heritability of ME milk yield was 0.31 indi- cating that improvement programs would be effective. Reproductive performance of Holstein Friesian cattle should be investigated in future studies. Acknowledgements I acknowledge the support of Engineer Abdulla Saif Al Darmaki, Chief Executive Officer of Al Ain Farms for Livestock Production. I would also like to thank Dr. Saleh Abdu Al Shorepy of the University of the United 2004 2005 2006 2007 10000 10500 11000 11500 12000 12500 Milk Production (L) Y ea r Season Summer Winter Figure 1. Effect of year and season of freshening on 305- day ME milk yield. 5000 7500 10000 12500 15000 2004 2005 2006 2007 Year M ilk P ro du ct io n (L ) Lactation Lact 1 Lact 2 Lact 3 Figure 2. Effect of year and season of lactation number on 305-day ME milk yield. 7Research Article ELboshra, Ali and Hassabo Arab Emirates, for his support and excellent information about heat stress. This manuscript was typed and edited by Mr. Walid Mirghany Mohammed of the Department of the President’s Affair in UAE. References Armstrong, D.V. 1994. Heat stress interaction with shade and cooling. Journal of Dairy Science, 77: 2044-2050. 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