Dairy Cattle Diet with Plant Extract

The occurrence of resistance of bacteria strains to related families of in-feed antibiotics, and consequent loss of efficacy of these drugs, as well as legislation restricting nitrogen and methane levels in the environment, have prompted the search for alternatives to conventional growth promoters deemed `natural´ yet efficacious.

A Ph.D. thesis sponsored by CaroTech® on plant extracts and their active ingredients has proven the added-value benefits of novel encapsulation technologies in the development of strategic products for ruminants.The project investigated the use of the plant extracts cinnamaldehyde (active ingredient of Cinnamomum spp., cinnamon) and garlic oil (key active ingredient of which is diallyl disulfide) as a dietary rumen modifier for dairy cattle feeds.

The effects of these two plant extracts were investigated on several levels:

1) in vitro mode of action
2) in vivo efficacy
3) safety on milk end product characteristics.

The objective of the in vitro study was to determine effects of five doses (0, 20, 60, 180 and 540 mg/L incubation medium) of cinamaldehyde (99% purity; CIN) and garlic oil (65% diallyl disulfide, GAR) in a quadruplicate 2 × 5 × 2 factorial arrangement of treatments, to determine their effects on in vitro fermentation using two substrate diets in batch cultures of mixed rumen micro-organisms from the rumen of sheep fed either a medium-concentrate diet (50:50 forage:concentrate ratio; MC) or a high-concentrate diet (15:85 forage:concentrate ratio; HC). Initial pH in the incubation medium was 6.98 and 6.39 for MC and HC inoculum, respectively.

As expected, differences (P < 0.001) in total VFA, acetate, propionate, butyrate, acetate:propionate, final pH, ammonia N, and methane were observed in MC versus HC diets, respectively The interaction between treatment and diet was significant for all measurements, except for isobutyrate, isovalerate, pH, N-NH3, lactate, and AFOM. Compared with Control in both MC and HC diets fermentations, respectively, CIN540 reduced (P < 0.05) total VFA; GAR180, GAR540, reduced (P < 0.05) acetate, and increased (P < 0.05) propionate; and GAR180, GAR540, and CIN 580 decreased (P < 0.05) gas production, methane concentration, methane/VFA proportion, methane proportion, and hydrogen recovery, and increased (P < 0.05) valerate. CIN60 decreased (P < 0.05) NNH3 in MC, CIN180 increased (P < 0.05) acetate:propionate ratio, and decreased (P < 0.05) N-NH3, and H2 recovery in MC, and CIN540 increased (P < 0.05) propionate, and decreased (P < 0.05) acetate in HC, and increased (P <0.05) butyrate, and decreased (P < 0.05) acetate in MC. GAR20 reduced (P < 0.05) methane, and H2 recovery in HC. GAR60 increased (P < 0.05) propionate, butyrate, and reduced (P < 0.05) acetate, and acetate:propionate ratio in MC. 

The results from this study are the first to show that CIN and GAR at different inclusion levels may elicit different fermentation responses, depending on the diet composition. Doses 180 and 540 of GAR altered ruminal microbial fermentation favours propionate, which is energetically more efficient. The results indicated that cinnamaldehyde and garlic oil showed different effect on in vitro ruminal fermentation depending on the administered dose, the substrate composition and micropopulations in the inoculum. This helps to explain the variation in the responses observed in the literature review and allowed to design the subsequent dairy cow feeding trials.

Two feeding trials were carried out in lactating Red Simmental dairy cows. Experiment 1 consisted in evaluating the effect on milk production of supplementing a high protein diet of cows in early lactation (average days in milk, DIM < 120 days) with cinnamaldehyde and garlic oil. Sixty-seven multiparious Red Holstein x Simmental dairy cows in early lactation were fed a forage-based diet over an 8-weeks period supplemented with 3 kg/day of a high protein concentrate alone or with cinnamaldehyde and garlic oil (Next Enhance 300, 129 mg/day of cinnamaldehyde and 21 mg/day of garlic oil standardised in dially disulfide 50% as fed). The ration was based on grass silage and hay and was fed ad libitum. After a 1-week co-variant pre-trial period, cows were assigned to one of two groups: the control group (CTR) fed a diet based on a forage ration but with high protein concentrate, or the treatment group (Next Enhance 300) fed the control diet with the high protein concentrate supplemented with Next Enhance 300. Concentrate intake, milk production and milk components were measured at morning and evening milkings over 2 days in the last week of each month.

There was an overall tendency for milk urea nitrogen to decrease from feeding of NE300 (P = 0.07). The time*treatment interaction was marked by a significant (P < 0.05) decrease in milk urea nitrogen from month 1 to month 2 of the trial, but the decrease was greater for animals fed Next Enhance 300 such that their milk nitrogen values were significantly (P < 0.01) lower than those of the control animals in month 2 (21.1 mg/dl Next Enhance 300 group versus 24.34 mg/dl CTR group, respectively). Milk protein content also tended to increase (P <0.09) with feeding of NE300 in the protein concentrate. Concentrate intake, milk production and other milk components (fat, lactose and somatic cell count) were unaffected.

This study shows that the feeding of high forage dairy diets with NE300 has potential to decrease milk urea nitrogen. Longer feeding periods may be necessary to observe significant and sustained effects, especially on milk production.

In the second trial, 25 lactating Red Simmental dairy cows were used to evaluate the effect of the addition of Next Enhance 300 on dairy cow performance in late lactation. Cows were assigned randomly to one of two treatments: control diet (forage with high protein concentrate, CTR) or the control diet supplemented with Next Enhance 300. There was no overall effect of feeding Next Enhance 300 in concentrate intake, however, there was a time*treatment interaction with a significant (P < 0.05) decreases in the intake of cows fed Next Enhance 300 in the second month of the study. There was a highly significant (P < 0.001) time*treatment interaction on milk urea concentrations. Animals fed Next Enhance 300 had significantly lower milk urea concentrations than CTR, an effect that became more pronounced with time on treatment. In month 1, NE300 group had 11% lower milk urea concentrations than CTR (27.47 mg/dl versus 30.42 mg/dl, respectively) and by month 3, this difference had increased to 37% (21.45 mg/dl versus 29.45 mg/dl, respectively).

There was a significant time*treatment interaction on milk production with dairy cows fed Next Enhance 300 producing significantly (P < 0.05) more milk in the last month compared to CTR (25.59 kg/d versus 22.35 kg/d respectively). There was a significant (P < 0.05) effect of treatment on milk fat concentration, with Next Enhance 300 animals yielding more milk fat than CTR (4.79 g/g CG versus 4.42 g/g, respectively). Feeding of Next Enhance 300 also significantly (P < 0.05) reduced milk somatic cell count compared to CTR (75.78 x 1000/ml versus 62.53 x 1000/ml. respectively). This study shows that the inclusion of NE300 in the dairy concentrate of cows fed forage-based diets has potential to improve milk production and milk composition when fed to dairy cows in late lactation.

Overall, test developed in Ljubljana University, Slovenia with high pressure liquid chromatography (HPLC) used for the identification of the active ingredient originating from Next Enhance 300 in the milk of dairy cattle fed over 30 days.

The Next Enhance 300 (129 mg/d cinnamaldehyde and 21 g/kg garlic oil) was incorporated into a concentrate diet. Milk was collected from morning and evening milkings on three separate days, pooled, and analysed for the presence of cinnamaldehyde, diallyl disulfide and allyl disulfide. The detection limit (DL) and the limit of quantification (LOQ) for cinnamaldehyde were established at 16.58 cf. 32.27 ng, respectively. The DL and LOQ for garlic oil based on its active ingredient diallyl disulfide was 19.60 and 57.79, respectively. Based on the DL and LOQ values, analysis of milk samples of dairy cows fed NE300 over 30 days at a feeding level of 129 mg/d and 21 mg/d, respectively, showed no detectable residues of cinnamaldehyde, or diallyl disulfide as an indicator of garlic oil in milk.

Results in this thesis illustrate that cinnamaldehyde and garlic oil as used in CaroTech´s Next Enhance 300 does yield effects on decreasing ammonia N, and improving energy utilisation. Of course, further work needs to continue on determining the effects of encapsulation and other protection systems on the stability and efficacy of plant extracts in order to be implemented in future dairy feeding programs as sustainable solutions.