مقايسه عملكرد توليدي، توليدمثلي و سلامت گاوهاي آميخته‌ مونت‌بليارد × هلشتاين وسيمنتال × هلشتاين با هلشتاين خالص در شرايط پرورشي دامداري صنعتي تحت اقليم نيمه گرمسيري مرطوب

Comparison of heat-stressed purebred Holstein vs. crossbred Holstein × Montbeliarde and Holstein × Simmental cows: Production, reproduction, metabolism and health

سابقه و هدف: فرضيه پژوهش اين بود كه گاوهاي آميخته‌ شيرده عملكرد بهتري نسبت به گاو هاي نژاد هلشتاين تحت شرايط پرورشي تنش‌ زا داشته باشند . هدف از پژوهش حاضر مقايسه عملكرد توليدي ، توليدمثلي و وضعيت سلامت و متابوليكي گاو هاي نژاد خالص هلشتاين با آميخته هاي سيمنتال × هلشتاين و مونت‌بليارد × هلشتاين در نيمه گرمسيري مرطوب در يك گاوداري صنعتي در ساري بود. مواد و روش ‌ها : اين تحقيق در واحد شير و گوشت مهدشت از شركت‌ هاي تابعه بنياد مستضعفان انقلاب اسلامي (مازندران ، ايران) انجام شد . آميخته‌ هاي شيري حاصل از تلقيح گاو هاي ماده هلشتاين با اسپرم نژاد هاي سيمنتال و مونت‌بليارد بودند. عملكرد گاو هاي آميخته با گاو هاي هلشتاين در زايش اول با استفاده از 70 راس به ازاي هر يك از سه گروه ژنتيكي (مجموع 210 راس تليسه) مورد مقايسه قرار گرفت . نمونه‌ هاي خون جهت انجام آزمايشات متابوليت‌ هاي خوني (شامل گلوكز، بتاهيدروكسي بوتيرات يا BHBA ، اسيد هاي چرب غير استريفيه يا NEFA ، كلسيم و منيزيم ) در زمان كلوزآپ (سه هفته قبل از زايش)، زمان زايش و 21 روز پس از زايش از دام‌ هاي تحت مطالعه (از هر گروه 15رأس) اخذ شد. تجزيه و تحليل آماري داده‌ها با استفاده از نرم افزار SAS انجام گرفت .ﯾﺎﻓﺘﻪ ﻫﺎ: ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از اﯾﻦ ﭘﮋوﻫﺶ ﻧﺸﺎن داد، ﺗﻔﺎوت ﻋﻤﻠﮑﺮد در ﺻﻔﺎت ﺑﺎروري، ﺗﻮﻟﯿﺪ ﺷﯿﺮ، ﻣﻘﺪار ﭼﺮﺑﯽ و ﭘـﺮوﺗ ﺌﯿﻦ 305 روز، دﻣﺎي رﮐﺘﺎل، درﺻﺪ ﻣﺮدهزاﯾﯽ، ورم ﭘﺴﺘﺎن، ﻟﻨﮕﺶ و ﺷﺎﺧﺺ ﻫﺎي ﻣﺘﺎﺑﻮﻟﯿﺖ ﺧﻮن ﮔﺎوﻫﺎي ﻫﻠﺸﺘﺎﯾﻦ ﺧﺎﻟﺺ ﻧﺴـﺒﺖ ﺑـﻪ آﻣ ﯿﺨﺘـﻪ ﻫـﺎ ﻣﻌﻨﯽدار ﻧﺒﻮد )0/05>P(. درﺻﺪ وﻗﻮع ﺳﺨﺖزاﯾﯽ آﻣﯿﺨﺘﻪ ﻣﻮﻧﺖﺑﻠﯿﺎرد × ﻫﻠﺸﺘﺎﯾﻦ ﻧﺴﺒﺖ ﺑـﻪ آﻣﯿﺨﺘـﻪ ﺳـ ﯿﻤﻨﺘﺎل × ﻫﻠﺸـﺘﺎ ﯾﻦ ﺑﻄـﻮر ﻣﻌﻨﯽداري ﺑﺎﻻﺗﺮ ﺑﻮد و ﻫﻤﭽﻨﯿﻦ ﺑﺮوز ﻣﺘﺮﯾﺖ آﻣﯿﺨﺘﻪﻫﺎ ﻧﺴﺒﺖ ﺑﻪ ﻫﻠﺸﺘﺎﯾﻦ ﺧﺎﻟﺺ ﺑﻪ ﻃﻮر ﻣﻌﻨﯽداري ﺑﺎﻻﺗﺮ ﺑﻮد )0/05

Comparison of heat stressed purebred Holstein vs. crossbred Holstein × Montbeliarde and Holstein × Simmental cows : Production, reproduction, metabolism and health Abstract Background and objectives : Crossbred lactating cows were hypothesized to outperform Holsteins under environmental stresses . The objective of this study was , therefore, to compare production, reproduction, metabolism and health of purebred Holstein cows vs . crossbred Holstein × Montbeliarde and Holstein×Simmental cows under hot and humid conditions of north of Iran ( Sari , Mazandaran ) . Material and methods : Dairy crosses were produced by crossing Holstein ( H ) cows with Montbeliarde ( M ) and Simmental ( S ) bulls’ semen . The performance and health of 70 primiparous cows from each breed ( 210 cows in total) were compared during their first lactation . Blood samples were taken from 15 primiparous cows from each breed at stages of close-up , calving , 21 days after calving. Samples were analyzed for glucose , BHBA, NEFA, calcium and mangium . Statistical analyses were performed using SAS programs ( GLM and MIXED procedures ). Results: Results showed that Montbeliarde × Holstein and Simmental×Holstein crossbred cows were not different (P> 0.05) from pure Holsteins in rectal temperature , fertility and other reproductive indices , 305-d milk yield, milk fat and protein yield, stillbirth, mastitis, and laminitis rates and close-up blood metabolites. However , Montbeliarde × Holstein cows had greater calving difficulty than did Simmental×Holstein cows (P < 0.05 ) . Also , both crossbred groups had higher incidence of metritis compared to purebred Holstein cows ( P < 0.05 ) . The purebred Holsteins exhibited more desirable udder traits than did crossbred cows (P < 0.05). The crossbred cows had more body condition score ( BCS ) during the transition period than did the pure Holsteins (p < 0.05 ). However, stature of Simmental × Holstein crossbred cows was shorter than pure Holstein . Foot angle was steeper for Holstein×Simmental and Holstein × Montbeliarde crossbred cows , but Holstein × Montbeliarde crossbred cows were similar to pure Holstein cows for hoof measurements . Conclusions: findings of this study suggest that Holstein×Simmental and Holstein × Montbeliarde crossbred cows did not outperform first - lactation purebred Holstein cows, and that they experienced higher rates of dystocia and metritis under stressful hot and humid conditions .