PSII-A-10 - Impact of Altered Photoperiod on Colostral Iga and Lactoferrin in Dairy Cattle

Abstract: Intake of poor-quality colostrum reduces thriftiness and survival of dairy calves and cost dairy producers in 2017 $70 per head for each calf receiving poor quality colostrum. Studies suggest levels of lactoferrin and IgA within good colostrum are 1.5 - 5 mg/ml and 5.36 mg/ml respectively. Today, producers are recommended to expose cows to short-day photoperiod (SDPP) during the dry period as this has been shown to increase milk production during the next lactation. However, the impact of SDPP on colostrum quality is unknown. The objective of this study was to determine the effect of day length during the entire dry period on the colostrum quality. We measured the levels of lactoferrin and IgA from both Jersey and Holstein dry cows (n=33) exposed to 8 hours of light for SDPP (n=9 Holstein, n=8 Jersey) or 16 hours of light for long-day photoperiod (LDPP) (n=8 Holstein, n=8 Jersey) using enzyme-linked immunosorbent assays (Bethyl Laboratories). Colostrum samples were collected from the cows, skimmed and frozen at -20oC until assayed. Data were analyzed with SAS 9.4. We found that the levels of lactoferrin and IgA did not differ between breed and photoperiod treatment (P = 0.57, P = 0.46, respectively). The average for lactoferrin in SDPP animals was 1.41 mg/mL and 1.55 mg/mL for LDPP. The average for IgA in SDPP animals was 5.08 mg/mL and 3.88 mg/mL for LDPP. Based on these data we suggest that dry period photoperiod exposure does not impact colostral IgA or lactoferrin levels.