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- Title
Effect of Rumen-Protected L-Tryptophan or L-Ascorbic Acid on Plasma Metabolites and Milk Production Characteristics of Lactating Holstein Cows during Summer Conditions.
- Authors
Kim, Young-Lae; Lee, So-Hee; Son, Gi-Hwal; Shin, Jong-Suh; Kim, Min-Ji; Park, Byung-Ki
- Abstract
Simple Summary: Summer heat stress adversely affects the productivity and economic viability of lactating Holstein cows. We explored the effects of dietary supplementation with L-tryptophan or L-ascorbic acid on milk production characteristics and plasma metabolites in lactating Holstein cows during the summer. The results showed that the supplementation with L-tryptophan or L-ascorbic acid reduced heat stress in lactating Holstein cows during the summer. In particular, L-tryptophan supplementation increased the concentration of melatonin in milk. However, there were no significant differences in milk yield or composition between the treatments. Therefore, further research is needed to explore the effects of increasing the dosage of supplements and to investigate the combination strategies of the dietary supplements used in the current study. This study investigated the effects of rumen-protected L-tryptophan or L-ascorbic acid supplementation on the productivity of lactating Holstein cows during a high-temperature period. Thirty cows were assigned to three dietary groups: control (CON), treatment 1 (TRT 1; rumen-protected L-tryptophan, 20 g/cow/d), and treatment 2 (TRT 2; rumen-protected L-ascorbic acid, 20 g/cow/d). As the high-temperature period progressed, the decrease in milk yield and dry matter intake (DMI) in the TRT 1 and TRT 2 groups was lower than that in the CON group. The total protein level in the plasma of the TRT 1 group was higher than that in the CON group (p < 0.05). Milk melatonin concentration was higher in the TRT 1 group than in the CON and TRT 2 groups (p < 0.05). Thus, the present results indicate that rumen-protected L-tryptophan or L-ascorbic acid has positive effects in preventing declines in DMI and milk yield by reducing heat stress in Holstein cows. In particular, rumen-protected L-tryptophan is considered effective in increasing the melatonin concentration in milk.
- Subjects
LACTATION in cattle; MILK yield; COWS; LACTATION; TRYPTOPHAN; BLOOD lactate; COMPOSITION of milk
- Publication
Animals (2076-2615), 2024, Vol 14, Issue 12, p1820
- ISSN
2076-2615
- Publication type
Article
- DOI
10.3390/ani14121820