Sward Factors Influence on Pasture Dry Matter Intake of Grazing Dairy Cows: A Review
محورهای موضوعی : Camel
آ.ال. روکا فرناندز
1
(Centro de Investigaciones Agrarias de Mabegondo, INGACAL, Apdo 10, 15080, A Coruna, Spain)
آ. گنزالو ردریگوئز
2
(Centro de Investigaciones Agrarias de Mabegondo, INGACAL, Apdo 10, 15080, A Coruna, Spain)
کلید واژه: defoliation frequency and intensity, grazing dairy cattle, grass feeding value, grass / legume species, sward characteristics, pasture dry matter intake,
چکیده مقاله :
Successful pasture-based milk production systems pivot on balancing dairy cows’ feed requirements with seasonal and annual fluctuations in pasture production. In order to maximise cow production from grazing dairy systems, it is necessary to reach an efficient utilization of grazed grass for feeding cows and the development of appropriate grazing management systems designed to maximize daily pasture dry matter intake (PDMI) per cow and per hectare, while maintaining high sward quality over the grazing season by keeping high pasture levels of crude protein, water soluble carbohydrates and digestibility of organic matter and low levels of acid and neutral detergent fibers in the swards. To maximize PDMI, cows need to consume plants that have characteristics that allow rapid consumption and lead to fast rates of passage through the rumen. This review considers the role of sward factors which affect the short-term feed budget of cows at pasture and, therefore, condition cow feed requirements at grazing and influence on PDMI. Furthermore, it highlights the relevance that havefor the development of pasture-based milk production systems the study of the species of grasses and / or legumes that integrate the pastures, the changes on sward structure, the seasonality in grass production, the pasture chemical constituents, the sward botanical composition, the grass feeding value, the digestibility of pastures, the intensity of sward defoliation, and the importance of sward height and herbage mass in relation to maximizing PDMI. The amount of herbage consumed is the major determinant of cow production but it is yet one of the most difficult aspects of forage quality to predict. In this review, three methods for PDMI calculation are presented as faecal output/diet digestibility method, sward difference method and the grazing-behaviour method. Also, three equations for PDMI estimation are described considering different sward and animal variables.
سیستم‌های موفق مرتعی تولید شیر، بر اساس ایجاد توازن بین نیازمندیهای خوراکی دام با نوسانات فصلی و سالیانه در تولید مرتع پایه‌گذاری شده‌اند. به‌منظور حداکثر نمودن تولید گاوهای شیری در سیستم‌های چرا، دست‌یابی به استفاده با راندمان از علوفه چرا شده و توسعه سیستم‌های مدیریتی مناسب جهت حداکثر نمودن مصرف روزانه ماده خشک مرتع توسط هر گاو و در هر هکتار، ضمن داشتن یک مرتع با کیفیت بالا در طی فصل رشد از طریق حفظ سطوح بالای پروتئین خام، کربوهیدرات‌های محلول درآب، هضم‌پذیری ماده خشک و سطوح پایین الیاف‌های قابل حل در شوینده خنثی و اسیدی، ضروری است. برای حداکثر نمودن ماده خشک مصرفی از مراتع، لازم است تا گاوها از گیاهانی مصرف نمایند که دارای شاخصه‌های مصرف سریع بوده و منجر به نرخ سریع عبور از شکمبه شوند. در این مرور عوامل مرتعی که روی تنظیم کوتاه‌مدت مصرف خوراک گاوها تأثیر‌گذار بوده و بنابراین نیازمندیهای خوراکی دام‌های چرا کننده را مشخص می‌کنند، مد نظر قرار گرفته‌اند. گرچه مقدار علوفه مصرفی یک عامل تعیین‌کننده عمده تولید گاوها است، اما برآورد آن هنوز یکی از مشکل‌ترین جنبه‌های کیفی علوفه برای پیش‌بینی می‌باشد. در این مرور به سه روش خروجی مدفوعی / قابلیت هضم جیره‌ای، روش تفاوت مرتع و روش رفتار چرا برای محاسبه مصرف ماده خشک مرتع اشاره شده است. همچنین، سه معادله در بر گیرنده متغییرهای مرتعی و حیوانی برای تخمین میزان مصرف ماده خشک مرتع توصیف می‌شوند.
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