2024 : 7 : 15
Mehdi Hossein Yazdi

Mehdi Hossein Yazdi

Academic rank: Assistant Professor
ORCID: https://orcid.org/0000-0003-3763-6507
Education: PhD.
ScopusId: 55332944500
Faculty: Agriculture and Environment
Address: Arak University


Forage source (alfalfa hay versus wheat straw) and rumen undegradable to degradable protein ratio: Effects on growth performance, microbial protein yield, digestibility, blood metabolites, and behavior of Holstein dairy calves
urea recycling, fiber, nitrogen efficiency, calf growth
Journal Spanish Journal of Agricultural Research
Researchers Milad Mohammadzadeh Ghomi ، Mehdi Kazemi bonchenari ، Mehdi Hossein Yazdi ، Mehdi Mirzaei


Aim of the study: The effects of forage source (alfalfa hay; AH vs. wheat straw; WS) with rumen undegradable to degradable protein ratio [low ratio (LR) = 28:72; high ratio (HR) = 36:64] were evaluated in young dairy calves. Area of study: Interaction of forage source and protein degradability in starter diet of dairy calves. Materials and methods: Forty-eight 3-d old female Holstein dairy calves (44.5 kg of BW) were allocated in four treatments: (1) AH with low dietary RUP:RDP ratio (AH-LR); (2) AH with high dietary RUP:RDP ratio (AH-HR); (3) WS with low dietary RUP:RDP ratio (WS-LR); and (4) WS with high dietary RUP:RDP ratio (WS-HR). The calves weaned on d 53 of the experiment and remained in the study until d 73 of age. Main results: The average daily gain and feed efficiency were improved in dairy calves receiving HR diets compared to LR diets during the post-weaning period (p < 0.05). The fecal score (p = 0.03) and neutral detergent fiber digestibility (p = 0.04) were improved when calves fed WS diets compared to AH diets. Feeding HR diets increased allantoin (p = 0.04) and microbial protein yield, and reduced blood urea nitrogen concentration (p = 0.03) compared to LR diets. Assessing the interaction effects of the experimental factors resulted that the greatest BW, wither height, and blood beta-hydroxybutyrate, and the lowest urinary nitrogen concentration were observed in the WS-HR treatment (p < 0.05). Research highlights: Feeding WS with high RUP:RDP ratio is recommendable in dairy calves due to the improvement in gain and nitrogen efficiency.