L.O. Ely

Identification and properties of yeasts associated with the aerobic deterioration of wheat and alfalfa silages

Populations of fungi in aerobically deteriorating wheat and alfalfa silages were identified as: Endomycopsis burtonii, E. selenospora, Hansenula canadensis, Candida tenuis and C. silvicola. The yeasts recovered were similar for both silages, but H. canadensis was recovered only in wheat silages. All of these yeasts could utilize lactic acid aerobically, but not anaerobically. Only Endomycopsis spp. could utilize propionic acid aerobically and none of the yeasts utilized this acid anaerobically. However, all yeasts grew in complete media supplemented with propionate. Therefore, while lactic and propionic acids may contribute to stability under anaerobic conditions, they are much less less effective after the silage is exposed to air.

Effects of Artificial Insemination vs Natural Service Breeding on Production and Reproduction Parameters in Dairy Herds

The effects of four combinations of AI and natural service (NS) breeding on production and reproduction parameters were analyzed using Holstein Dairy Herd Improvement herd summary records for years 1999 through 2002. Herds were assigned to breeding systems (BS) by percentage of NS usage as follows: 1) 0%, 2) 1 to 20%, 3) 21 to 89%, and 4) 90 to 100%. Regions were North, Midsouth, and South. Herd sizes were small ( 250 cows). The mean percentages of AI and NS usage over 4 yr by BS were 1) 100%, 0%; 2) 92.9%, 7.1%; 3) 54.2%, 45.8%; and 4) 1.0%, 99.0%. Actual calving interval was shorter (P<0.05) for BS4 compared with the other systems. Herds using a combination of AI and NS (BS2 and BS3) had longer actual calving intervals than did herds in BS1 (P<0.05). Days dry and the percentage of dry periods between 40 to 70 d were less for BS1 (P<0.05). The percentage of cows leaving the herd was significantly less for BS4. The percentage of cows leaving the herd for reproductive reasons was greater for BS1 (P<0.05). Overall reproductive efficiency as measured by the percentage of cows in milk and herd milk yield was greater (P<0.05) for BS1 and declined as the percentage of NS increased. Actual calving interval, days dry, and percentage of dry periods between 40 to 70 d were less in the North (P<0.05). Percentage of cows in milk and herd milk yield were greater in the North (P<0.05). Herd milk yield was greater (P<0.05) for large-size herds and decreased with declining herd size.

0105 Serum and colostrum antibody titers in Holstein cows, and the relationship between these titers and serum antibody titers in their calves.

Abstract Vaccination of cows in late gestation is sometimes used to improve maternal antibody titers in their calves. However, scant published research has reported the relationship between serum antibody titers to specific infectious agents in vaccinated cows, the colostrum of these cows, and the serum of calves consuming their colostrum. As part of a larger study, the relationship between cow serum and colostrum antibody titers and calf titers was evaluated. Fifty-four multiparous Jersey and Jersey-cross cows were vaccinated between dry-off and calving with commercially available vaccines containing bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), rotavirus, coronavirus, E. coli J-5, and Salmonella siderophore receptor and porin (SRP); blood was collected at dry off, mid-dry, and at calving. Calves born to enrolled cows were fed colostrum from only their dams; calf serum was collected at 7 and 30 d of life. Antibody titers against agents in the vaccine were measured in serum and colostrum of cows by standard neutralizing techniques or ELISA, and correlations between cow serum antibodies at 30 d before calving, cow colostrum, and calf serum antibodies at 7 d of life were evaluated. Correlations between cow serum antibodies and colostrum antibodies for different agents were significant (P < 0.05) but only moderately strong (Pearson correlation coefficient [PCC] range: 0.32–0.7), and varied for different agents. Similarly, correlations between cow colostrum antibodies and calf serum antibodies were usually significant, but only moderate (PCC range: 0.36–0.77). The R2 value for the correlation between colostrum antibodies and calf antibodies ranged from 0.11–0.59, indicating that for most agents, the colostrum antibody titer to a given agent did not explain a majority of variation in the calf serum antibody titer to that agent. Antibody titers to specific agents in cows are significantly, but not strongly, correlated with their colostrum antibody titers, and colostrum antibody titers are significantly but not strongly, related to antibody titers in calves. These data suggest that, in addition to maternal antibody concentration, other factors have an important impact on serum antibody titers to specific infectious agents in young dairy calves.