Effects of subcutaneously injected Ca Cu EDTA on concentrations of Cu in liver, milk production and reproductive performance in New Zealand dairy cowsAuthors: Hawkins D
Publication: New Zealand Veterinary Journal, Volume 62, Issue 5, pp 244-249, Sep 2014
Publisher: Taylor and Francis
AIMS: To determine the effect of dose and frequency of injection of Cu as Ca Cu EDTA on concentrations of Cu in liver, and the effect of a single 200â€…mg treatment on milk production and reproductive performance in New Zealand dairy cows.
METHODS: Four groups of dairy cows (n=18 per group) on three farms were injected with 100 or 200â€…mg Cu S/C once, or three times at 6-weekly intervals, commencing 6âˆ’8 weeks into lactation. Concentrations of Cu in liver were determined to 119 days after treatment. Cows at peak lactation on one farm were treated with 200â€…mg of Cu S/C, or received no treatment (n=92 per group). Milk production was determined 11 days before and 24 hours following treatment. In seven dairy herds from throughout New Zealand cows were injected S/C with 200â€…mg Cu 10 days prior to mating start date (MSD) or received no treatment. Oestrus detection and artificial inseminations were carried out for â‰¥24 days from MSD. Pregnancy diagnosis was performed at 12 weeks following MSD. The percentage of cows inseminated in the 21 days after MSD (21-day submission rate; n=2,022) and cows pregnant after 21 or 28 days (21- and 28-day pregnancy rates; n=2520) was determined.
RESULTS: Injecting with 200â€…mg Cu once or 6-weekly increased concentrations of Cu in liver compared with 100â€…mg (p<0.05). Injection of 200â€…mg Cu decreased total milk yield (p=0.006) and protein production (p<0.001) in the 24âˆ’36â€…hours after treatment. Compared with Control cows, 200â€…mg Cu 10 days before MSD reduced 21-day submission (78 vs. 75%; p=0.04) and 21-day pregnancy rates (47 vs. 43%; p=0.03). For 28-day pregnancy rates there was a farm by treatment interaction (p=0.02), with a negative effect observed on some, but not other, farms.
CONCLUSIONS: Injection of 200â€…mg Cu raised concentrations of Cu in liver for >42 days. A negative impact on milk yield and composition occurred immediately following injection. Injection 10â€…days prior to mating had a negative effect on submission and pregnancy rates. Further study is required to determine a safe treatment to mating interval and the mechanism by which adverse impacts occur.
CLINICAL REVELENCE: Although 200â€…mg of Cu as Ca Cu EDTA is an effective supplement and generally well tolerated, determining the necessity for, and giving specific thought to the timing of, parenteral Cu supplementation is imperative to avoid negative impacts on herd production and reproductive performance.
KEY WORDS: Copper, supplementation, Ca Cu EDTA, dairy cattle, liver, fertility, reproduction, production, milk composition