Abstract
Four dairy cows in a positive energy balance were used to study the effect of propylene glycol supplementation variants on blood indices. The treatments were: without glycol, glycol mixed with the total mixed ration (TMR), glycol delivered as top dressing (TD), and glycol administered as an oral drench (OD). Oral drenching had the positive effect of higher blood insulin concentration 1.5 and 2.5 h after supplementation compared to the TD method (P ≤ 0.05). Glycol supplemented as TD had the negative effect of higher concentration of non-esterified fatty acids (NEFA) 3.5 h after supplementation (P ≤ 0.05) with a trend towards a higher mean concentration of this marker (P ≤ 0.1). A decreasing tendency was recorded for the NEFA concentration 1.5 h after glycol supplementation with TMR or OD (P ≤ 0.1). Glycol supplemented as OD had the positive effect of lowering the β-hydroxybutyric acid concentration 1.5 and 2.5 h after feeding (P ≤ 0.05). A downward trend in the mean β-hydroxybutyric acid level after glycol delivery as OD was also observed (P ≤ 0.1). Glycol supplemented as TD had the negative effect of decreasing dry matter intake of the diet (P ≤ 0.05). Glycol supplemented as OD had a more glucogenic effect than as part of the TMR. Due to reduction of dry matter intake and the lowest glucogenic effect, using glycol as TD is unjustified. The results confirm that the best method of propylene glycol administration is OD, which can be useful in the prevention of ketosis, however, it should be confirmed in a long-term experiment covering the transition and early lactation periods.
Highlights
Over the last years, dairy cows have undergone genetic selection which has increased milk production to a level where it is difficult to meet the nutrient requirements with the diet (Mulligan and Doherty 2008)
The experimental treatments were as follows: CON — without propylene glycol; TMR — 400 ml/d of Propylene glycol (PG) mixed with the morning part of total mixed ration (TMR); TD — 400 ml/d of PG delivered as top dressing on the morning part of TMR; OD — 400 ml/d of PG delivered as oral drenching in the same time when TMR was delivered
TMR – total mixed ration, DM – dry matter, UFL – feed unit for lactation (1700 kcal NEL), PDIN – dietary protein undegraded in the rumen, but truly digestible in the small intestine and microbial protein which could be synthesized in the rumen from degraded dietary nitrogen, when energy and other nutrients are not limiting, PDIE – dietary protein undegraded in the rumen, but truly digestible in the small intestine and microbial protein which could be synthesized in the rumen from the energy available in the rumen, when degraded nitrogen and other nutrients are not limiting, LFU – fill unit for lactating dairy cows, VDMI – voluntary dry matter intake provide inconsistent information concerning the positive, glucogenic effect of PG feed of dairy cattle
Summary
Dairy cows have undergone genetic selection which has increased milk production to a level where it is difficult to meet the nutrient requirements with the diet (Mulligan and Doherty 2008). An increased NEFA level in dairy cows’ blood during a negative energy balance is often associated with the accumulation of triglycerides in hepatocytes, impairing liver function and elevating ketone production. Propylene glycol (PG) is a glucogenic precursor, its supplementation is one of the methods used in the treatment of ketosis in postparturient dairy cows. Address for correspondence: Robert Mikuła Department of Animal Nutrition Poznań University of Life Sciences Wołyńska 33, 60–637 Poznań, Poland to propionate It directly increases the propionate concentration in the rumen and can be converted to glucose via gluconeogenesis in the liver (Nielsen and Ingvartsen 2004). Many authors claim that propylene glycol could be effective in reducing the NEFA concentration in blood (Rizos et al 2008; Liu et al 2009). The aim of this study was to determine the glucogenic and antiketotic effect of PG supplementation methods in dairy cows
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