C. Grainger

Potential use of Acacia mearnsii condensed tannins to reduce methane emissions and nitrogen excretion from grazing dairy cows

We measured the effect of condensed tannins (CT) extracted from the bark of the Black Wattle tree (Acacia mearnsii) on the milk production, methane emissions, nitrogen (N) balance and energy partitioning of lactating dairy cattle. Sixty lactating cows, approximately 32 d in milk grazing ryegrass pasture supplemented with 5 kg d-1 cracked triticale grain, were allocated to three treatments: Control, Tannin 1 (163 g CT d-1) or Tannin 2 (326 g CT d-1 initially, reduced to 244 g d-1 CT by day 17). Cows were dosed twice daily after milking for 5 wk with the powdered CT extract (mixed 1:1 with water). Low and high CT supplementation reduced (P < 0.05) methane emissions by 14 and 29%, respectively (about 10 and 22% on an estimated dry matter intake basis). However, milk production was also reduced by the CT (P < 0.05), especially at the high dose rate. Milk yields were 33.0, 31.8 and 29.8 kg cow-1 d-1. Tannin 2 also caused a 19% decline in fat yield and a 7% decline in protein yield, but protein and lactose cont...

Supplementation with whole cottonseed causes long-term reduction of methane emissions from lactating dairy cows offered a forage and cereal grain diet.

The objective of our work was to supplement a forage and cereal diet of lactating dairy cows with whole cottonseed (WCS) for 12 wk and to determine whether the expected reduction in CH(4) would persist. A secondary objective was to determine the effect of supplementing the diet with WCS on milk yield and rumen function over the 12-wk feeding period. Fifty lactating cows were randomly allocated to 1 of 2 diets (control or WCS). The 2 separate groups were each offered, on average, 4.2 kg of DM/cow per day of alfalfa hay (a.m.) and 6.6 kg of DM/cow per day of ryegrass silage (p.m.) on the ground in bare paddocks each day for 12 wk. Cows in each group were also individually offered dietary supplements for 12 wk in a feed trough at milking times of 5.4 kg of DM/cow per day of cracked wheat grain and 0.5 kg of DM/cow per day of cottonseed meal (control) or 2.8 kg of DM/cow per day of cracked wheat grain and 2.61 kg of DM/cow per day of WCS. The 2 diets were formulated to be similar in their concentrations of CP and ME, but the WCS diet was designed to have a higher fat concentration. Samples of rumen fluid were collected per fistula from the rumen approximately 4 h after grain feeding in the morning. Samples were taken from 8 cows (4 cows/diet) on 2 consecutive days in wk 2 of the covariate and wk 3, 6, 10, and 12 of treatment and analyzed for volatile fatty acids, ammonia-N, methanogens, and protozoa. The reduction in CH(4) emissions (g/d) because of WCS supplementation increased from 13% in wk 3 to 23% in wk 12 of treatment. Similarly, the reduction in CH(4) emissions (g/kg of DMI) increased from 5.1% in wk 3 to 14.5% in wk 12 of treatment. It was calculated that the average reduction in CH(4) emissions over the 12-wk period was 2.9% less CH(4) per 1% added fat, increasing from 1.5% in wk 3 to 4.4% less CH(4) in wk 12. There was no effect of WCS supplementation on rumen ammonia-N, rumen volatile fatty acids, rumen methanogens, and rumen protozoa. On average over the 12-wk period, supplementation with WCS decreased the yield of milk (10%), fat (11%), protein (14%), lactose (11%), and fat plus protein (12%) and BW gain (31%). The WCS supplementation had no effect on milk fat concentration but resulted in a decrease in concentration of protein (5%) and lactose (11%). The major finding from this study is that addition of WCS to the diet of lactating dairy cows resulted in a persistent reduction in CH(4) emissions (g of CH(4)/kg of DMI) over a 12-wk period and that these reductions in CH(4) are consistent with previous work that has studied the addition of oilseeds to ruminant diets.

Use of corn distillers' dried grains to reduce enteric methane loss from beef cattle.

There are significant emissions of greenhouse gases (GHG) from agriculture, and a major source is enteric methane (CH4) from ruminants. Our study reports the impact on enteric CH4 emissions when barley grain (35% of the dietary dry matter (DM) was replaced by corn distillers’ dried grains with solubles (DDGS, adding 30 g fat kg-1 dietary DM) in the backgrounding diet of growing beef cattle. The addition of DDGS reduced CH4 emissions (g d-1) by 19.9%, and by 16.4% when adjusted for DM intake [g (DM intake)-1] or by 23.9% when adjusted for gross energy (GE) intake (% of GE intake). Adding DDGS to cattle diets reduced CH4 emissions, but the effects of higher N content of the manure on emissions of nitrous oxide and ammonia need to be accounted for to complete the evaluation of the environmental impact of feeding DDGS to feedlot cattle. Key words: Methane, beef cattle, corn distillers’ dried grains with solubles, lipid, greenhouse gas emissions, sulphur hexafluoride

Supplementation with whole cottonseed reduces methane emissions and can profitably increase milk production of dairy cows offered a forage and cereal grain diet

The experimental objective was to determine if whole cottonseed (WCS) could be used as a dietary supplement to reduce enteric methane emissions and profitably increase milk production from dairy cattle over the summer period when pasture is limited in quantity and has a low nutritive value. Fifty lactating cows, ~200 days in milk, were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (in the morning) and pasture silage (in the afternoon) made from a predominantly ryegrass sward in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg DM/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of untreated WCS with their grain supplement. Measurements of methane emissions (n = 12), using the SF6 tracer technique, were made in weeks 3 and 5 after the commencement of feeding treatments. Supplementation with WCS significantly reduced methane emissions by 12% (g/cow.day) and by 21% (g/cow.kg milk solids) and significantly increased yield of milk (n = 25) by 15%, milk fat by 19% and milk protein by 16%. WCS had no effect on concentration of milk fat or lactose, but resulted in a significant 3% decrease in protein concentration. WCS appears to be a promising supplement for reducing methane emissions and increasing milk production from dairy cattle when pasture is limited in quantity and has a low nutritive value.

Use of monensin controlled-release capsules to reduce methane emissions and improve milk production of dairy cows offered pasture supplemented with grain.

We examined the effects of monensin, provided by controlled-release capsules, on the enteric methane emissions and milk production of dairy cows receiving ryegrass pasture and grain. In a grazing experiment, 60 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows in the monensin group received 2 controlled-release capsules, with the second capsule administered 130 d after the first. Milk production was measured for 100 d following insertion of each capsule. The sulfur hexafluoride tracer gas technique was used to measure enteric methane emissions for 4 d starting on d 25 and 81 after insertion of the first capsule, and on d 83 after insertion of the second capsule. All cows grazed together as a single herd on a predominantly ryegrass sward and received 5 kg/d of grain (as-fed basis). In a second experiment, 7 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin controlled-release capsules on methane emissions and dry matter intake. Methane emissions were measured on d 75 after capsule insertion by placing cows in respiration chambers for 3 d. Cows received fresh ryegrass pasture harvested daily and 5 kg/d of grain. The release rate of monensin from the capsules used in both experiments was 240 +/- 0.072 mg/d, determined over a 100-d period in ruminally cannulated cows. The monensin dose was calculated to be 12 to 14.5 mg/kg of dry matter intake. There was no effect of monensin on methane production in either the grazing experiment (g/d, g/kg of milk solids) or the chamber experiment (g/d, g/kg of dry matter intake). In the grazing study, there was no effect of monensin on milk yield, but monensin increased milk fat yield by 51.5 g/d and tended to increase milk protein yield by 18.5 g/d. Monensin controlled-release capsules improved the efficiency of milk production of grazing dairy cows by increasing the yield of milk solids. However, a higher dose rate of monensin may be needed to reduce methane emissions from cows grazing pasture.

A high dose of monensin does not reduce methane emissions of dairy cows offered pasture supplemented with grain

The primary objective of our research was to determine the effect of a high dose of monensin supplementation on enteric CH(4) emissions of dairy cows offered a ryegrass pasture diet supplemented with grain. An additional objective was to evaluate effects on milk production and rumen function, because a commensurate improvement in milk production could lead to adoption of monensin as a profitable strategy for methane abatement. Two experiments were conducted (grazing and respiratory chambers) and in both experiments monensin (471 mg/d) was topdressed on 4 kg (dry matter)/d of rolled barley grain offered in a feed trough twice daily at milking times. In the grazing experiment, 50 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows grazed together as a single herd on a predominantly ryegrass sward and received monensin over a 12-wk period, during which time measurements of milk production and body weight change were made. The SF(6) tracer technique was used to estimate methane production of 30 of the 50 cows (15 control cows and 15 monensin cows) for 3 consecutive days in wk 3, 5, 8, and 12 of treatment. Samples of rumen fluid were collected per fistula from 8 of the 50 cows (4 per diet) on 2 consecutive days in wk 3, 5, 8, and 12 of treatment and analyzed for volatile fatty acids and ammonia-N. In the metabolic chamber experiment, 10 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin on methane emissions, dry matter intake, milk production, and body weight change over a 10-wk period. Methane emissions were measured by placing cows in respiration chambers for 2 d at wk 5 and 10 of treatment. Cows received fresh ryegrass pasture harvested daily. Monensin did not affect methane production in either the grazing experiment (g/d, g/kg of milk) or the chamber experiment (g/d, g/kg of dry matter intake, g/kg of milk). In both experiments, milk production did not increase with addition of monensin to the diet. Monensin had no effect on body weight changes in either experiment. Monensin did not affect volatile fatty acids or ammonia-N in rumen fluid, but the acetate to propionate ratio tended to decrease. Monensin did not improve milk production of grazing dairy cows and no effect on enteric methane emissions was observed, indicating that monensin cannot be promoted as a viable mitigation strategy for dairy cows grazing ryegrass pasture supplemented with grain.

Composition, coagulation properties, and cheesemaking potential of milk from cows undergoing extended lactations in a pasture-based dairying system

Extending the lactation length of dairy cows beyond the traditional 10 mo toward lactations of up to 22 mo has attracted interest in the pasture-based seasonal dairying systems of Australia and New Zealand as a way of alleviating the need for cows to conceive during peak lactation, such as is required to maintain seasonally concentrated calving systems. Lactation lengths longer than 10 mo instead provide cows with more time to cycle and conceive after parturition and may therefore be more suitable systems for high-producing Holstein-Friesian cows. Before recommending such systems there is a need to evaluate the effects of long lactations on the suitability of milk for manufacture of high-quality dairy products. In the current experiment, the composition of milk from cows entering the second half of a 22-mo lactation was examined in detail and compared with that from cows undergoing a traditional 10-mo lactation. On 2 occasions, coagulation properties were measured using low amplitude strain oscillation rheometry, and Cheddar cheese was made in 250-L pilot-scale vats. Results showed that milk from extended lactations had higher concentrations of fat and protein than cows undergoing 10-mo lactations under similar management conditions and at the same time of year. The ratio of casein to true protein was not affected by lactation length and neither were the proportions of individual caseins. The increase in milk solids during extended lactations translated into a more rapid rate of coagulation and ultimately a firmer curd on one of the two occasions. Milk from extended lactations yielded more cheese per 100 kg of milk, and there were few differences in the composition or organoleptic properties of the cheese. These data are the first to show that pasture-based dairy industries could embrace the use of extended lactations without compromising the core business of producing high-quality dairy products.

Effect of whole cottonseed supplementation on energy and nitrogen partitioning and rumen function in dairy cattle on a forage and cereal grain diet

The experimental objective was to determine the effect of adding whole cottonseed (WCS) to a forage and cereal grain diet on the energy and nitrogen balance and rumen function of lactating dairy cattle. Two experiments were carried out, a field experiment and an indoor metabolism experiment. In the field experiment, 50 lactating cows ~200 days in milk were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (morning) and ryegrass-based pasture silage (afternoon) in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg dry matter (DM)/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of WCS with their grain supplement. Samples of rumen fluid were collected from each fistula, ~4 h after grain feeding in the morning, of eight cows (four per group) on 1 day in each of the 5 weeks of treatment. In the metabolism experiment, immediately after the 5 weeks of feeding, 12 lactating cows, six from each treatment from the field experiment, were randomly selected and individually housed in metabolism stalls and fed the same diets for a 6-day energy and nitrogen balance study. Cows were fed at milking times (0700 and 1530 hours) and all feed offered and refused was weighed daily. All cows were offered 5.6 kg DM/cow.day of pasture silage, 4 kg DM/cow.day of lucerne hay and 3 kg DM/cow.day of cereal grain. In addition, cows in the WCS treatment group were offered 2.7 kg DM/cow.day of WCS with their grain supplement. In the metabolism study, adding WCS to the diet resulted in a greater energy intake, but there was no depression in energy digestibility. Whole cottonseed also increased nitrogen intake and nitrogen digestibility of the diet was increased from 62 to 75%, but the proportion of nitrogen in milk remained the same with a greater proportion of nitrogen appearing in body tissue. In the field experiment, supplementation with WCS did not alter rumen fluid ammonia-N or volatile fatty acid concentrations. Adding WCS did not affect three of the main classes of protozoa, based on size, within the two major orders of ciliate protozoa. The WCS did, however, reduce the levels of entodiniomorphs >200 µm diameter and holotrichs < 200 µm diameter, but these only account for a small number of the total protozoa present. Supplementation of a forage and grain-based diet with WCS improved the energy and protein content of the diet without any negative effects on rumen digestion and with a similar proportion of dietary energy and nitrogen appearing in milk. Over the summer period in winter-rainfall dairying areas in south-east Australia when pasture availability is limited and the diet is mainly comprised of forage and cereal grain fed at a level that is energy-limiting for maximum production, WCS can be and is used to supplement the diet to improve milk yield and profitability.