Peripartal propylene glycol supplementation and metabolism, animal health, fertility, and production in dairy cows.

The effect of peripartal supplementation with concentrate enriched at 10% propylene glycol (PG) on metabolism, animal health, fertility, and milk production was studied using 234 cows from 8 dairy farms with production averages of 8019 to 10,656 kg/yr. The feeding schedule for the PG group (n=117) was as follows: 13 d antepartum: 1.5 kg/d (= 150 mL PG); 12 d antepartum until parturition: 3 kg/d (= 300 mL PG); 1 to 12 d postpartum: 1 kg/d (= 100 mL PG). Control cows (n=117) received the same concentrate without PG. From a subset of cows (PG: n = 43; control: n = 40), blood samples were collected at 6, 3, and 1 wk antepartum, 3 d antepartum, on the day of parturition, and 1, 3, 5, 7, 9, and 11 wk postpartum for the determination of nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), insulin-like growth factor (IGF)-I, and activities of aspartate-aminotransferase (AST) and glutamate-dehydrogenase (GLDH). From another subset of cows (PG: n=11; control: n=10), blood samples were collected 1 wk antepartum, on the day of parturition, and 1 wk postpartum to determine immunophenotypical and functional parameters of blood neutrophils. From 1 wk antepartum to 1 d postpartum, concentrations of NEFA were significantly lower in cows receiving PG compared with controls. Also, concentrations of BHBA in cows receiving PG were significantly lower from 1 wk antepartum until 7 wk postpartum. Concentrations of IGF-I were significantly higher in the PG group, from 1 wk antepartum until 1 wk postpartum than in the control group. Activities of AST and GLDH did not differ between groups. Immunophenotypical and functional characteristics of blood neutrophils were not influenced by treatment nor were animal health, reproduction, or milk production. Although indicators of metabolic status were improved by peripartal use of PG-enriched concentrate, economic benefits are questionable for dairy farms with good nutritional programs, as economically important factors such as milk production, animal health, and fertility were not influenced.