Rate-of-passage is a very important concept for both cow health, and especially, feed conversion efficiency – feed dollars to milk dollars. It is also a tension, that is, too fast from very lush pasture or sub-optimal rumen pH, will reduce feed conversion efficiency and increase feed cost per litre significantly, not to mention cow health. Our valuable feed ends up in manure pats in the paddock instead of milk in the vat. Alternately, high fibre feeds such as poor quality/mature silage or hay, will slow down rate-of-passage of feed through the digestive tract, reducing daily feed intake and crashing milk production. In both cases, the feed cost per litre will escalate.

The starting point is always cows’ access to sufficient feed to be fully fed. Then there are two states of being ‘fully fed’. Full to contentment, and physically gut fill. Obviously physical gut fill is the goal of optimum milk production, reduced cost per litre from dilution of maintenance energy cost, and maximised profit which usually is accompanied by cow health.

Assuming cows do have access to sufficient feed, which is not common outside spring, the next limitation is palatability. Feed, be it pasture, summer crops, silage, grain or anything else, must first be highly palatable to achieve potential feed intake. Now back to rate-of-passage.

High fibre feeds spend long periods in the rumen being broken down sufficiently to pass into the abomasum, the true stomach. This reduces rate-of-passage to the extent that feed intake is also reduced with consequent reduction in milk production, higher feed cost per litre, as above, maintenance energy cost per litre, all culminating, and by a multiplier effect, in a crash in profit.

Feed NDF% (Neutral Detergent Fibre – total fibre in any given feed or ration), really does not tell us much as far as predicting milk production and profit from this feed or ration. Digestibility is the key.

Good feed analysis laboratories will supply 24 hr, 30 hr and 240 hr digestibility rates for feeds submitted for testing. Although there is some debate among academics as to which, 24 or 30 hr digestibility rates, are best to predict milk outcomes, my simplistic understanding prefers the 24 hr digestibility data. Why? Because we all work on 24 hr milk production systems to inform us as to how we are producing.

The 24 hr digestibility is telling us how much fibre is still in the rumen from yesterday, and how much that is going to reduce our cow’s feed intake today; and her milk production/profit.

Let’s look at two examples of pasture from our feed test library: 1) Actively growing/short rotation ryegrass – 24 hr digestibility 81.48%, sampled in June 17. 2) Slow growing/long rotation ryegrass – 24 hr digestibility 51.73%, sampled in November 16.

If we fed 10 kgs DM (dry matter) of each pasture to two groups of cows the difference in ryegrass digested and converted to milk would be 1) 8.148 kgs DM, 2) 5.173 kgs DM. Now, to compound the issue, the quality pasture has an ME (energy value) of 10.26 MJME/kg DM. The mature ryegrass has an ME of 9.18 MJME/kg DM.

Now, our cows digesting 8.148 kgs DM of the quality 10 kg DM pasture would convert that to 14.9 lts of milk. The cows consuming 10 kgs DM of the mature pasture and digesting only 5.173 kgs DM would convert that to 8.48 litres of milk. There is $1.57 difference in milk production at 40c/lt between each group of cows! Essentially, $1.57 difference in profit.

The plot thickens: The group of cows consuming the quality pasture will have 1.852 kgs DM fibre still in their rumens tomorrow reducing their feed intake for tomorrow and limiting tomorrow’s milk production by 3.39 lts. The cows consuming the mature pasture will have 4.827 kgs DM fibre remaining in their rumens tomorrow. This reduces their feed intake tomorrow and reduces milk production by 7.91 lts.

Yes this is an extreme example for the purpose of highlighting the influence of 24 hr digestibility, as no forage fibre is 100% digestible in 24 hrs. The lesson stands nevertheless, and has devastating impacts on farm profit from not managing grazing particularly, but even worse, time/maturity stage of cutting pasture for silage’s impact on 24 hr digestibility. We have silage test data on hand with variations in 24 hr digestibility between 77% and 49%.

The Remedies

Pasture: Short rotations of actively growing and regularly re-pastured stands. This is easily done with strategic fertilizer applications and produces healthy plants. Healthy pasture plants then produce healthy soils, there is a synergy here between these two, but it starts with healthy and actively growing plants. A system proven to achieve this is light applications of a complete blend after every grazing – 21 days. Fertilizer can be reduced once soils are health and vital. Fertilizer is always the cheapest feed!

Silage: As above, maturity at cutting is number one. Time between cutting and ensiling is number two (see our article ‘Silage in a Day’ sept 15). Third is a quality lactic acid bacterial silage inoculant containing a proven enzyme pack. Enzymes will break down indigestible fibre converting it to sugars for lactic acid producing bacteria to convert to lactic acid – high palatability/silage intake. This reduction in indigestible fibre will increase 24 hr digestibility and milk production from each kg DM of silage.

As a general statement, few would dispute home grown feeds are cheapest. However, we need to look at this more closely. Should we talk just feeds per se, or energy? It is energy we convert to milk. We should be discussing the cost of energy in any given feed when deciding what is cheapest. Effectively, feed dollars converted to milk dollars for this is the real determinant of profit.

That’s the simple equation, but from there on it can become quite complicated by debates over the cost of grass, by rates of digestibility (a subject I want to address next month), and by rumen health/function or feed conversion efficiency. We will leave these complications out of this discussion as my goal is to drive forage production on farm to at least validate the mantra of home grown feeds being the cheapest.

Home grown forage may or may not be the cheapest forage, but grain generally stands alone on energy cost. Home grown forage cost depends heavily on the value of the land it is grown on, the yield per annum per hectare, its digestibility and energy density. For our regular monthly clients we can determine grass grazed in tonnes of dry matter (TDM) and collate monthly averages for the full year. We can add to this quite accurately TDM silage, measure summer crops and cost each out. Due to wide variations between farms on the above criteria, we choose to take a mean value for grazed pasture at $250/TDM. This gives us a basis for silage cost, and good comparative data within farms from year to year.

I believe the district average for SW Victoria is in the vicinity 4 to 4.5 TDM/ha pasture harvested (machine or grazed). Yet we are aware of farms where we have measurement from monthly consumption, harvesting 10 TDM/ha and higher. Obviously, there is a massive difference in pasture cost irrespective of additional input cost to achieve this high TDM/ha. There usually is a serendipitous increase in digestibility with higher yielding farms, and this only magnifies the feed to milk dollar conversion potential/profit.

I raise this subject each year around July/August as that is when we prepare Feed Budgets for our clients. It is the most-timely part of the season to do so, so we can plan summer forage crops types/hectares etc., estimate silage requirements including our goal of 50% extra for reserves, based on the previous year’s forage harvested over each farm. Solid silage reserves can insulate us significantly from the many vagaries of season, grain and milk price we are subject to these days. Achieving these silage reserves also come under our summer cropping program with crops such as sorghum.

Over many years of preparing Feed Budgets for clients, compounded by observations, we have come to realise some of the limitations to home grown forage production. Things like compaction – pasture plants pulled up by grazing cows due to shallow rooting. Declining plant densities, and falling yields which are now known to be associated with lack of rotational crops. Differing plant species remove and deposit different things in soil, but all contribute to improved yields. There are synergies to yield through plant rotations. To resolve these impediments to yield we developed a Seven Year Paddock Plan for each of our clients. The goal is to address the above limitations, improve soil health/organic matter and yield capacity. The basic idea is two years in crops, up to three crops per year, then back to pasture for five years.

We believe, based on overseas data, that we can increase home grown forage harvested and hence lower the cost of feed, or rather, the cost of energy harvested/ha, through crop rotations. This principle has been known and practiced, especially by cereal grows, for many years. Both land (due to land value), and cows (due to maintenance energy cost), have fixed costs that can only be diluted to the benefit of profit, by increased yield – either TDM/ha or litres/cow.

Our potential to achieve this in our dairying areas is massive. The next ‘big thing’, we believe. We have clients that have achieved dramatically increased TDM harvested over their farms simply through summer fodder crop programs. We are now taking that to a new level with a more holistic plan spanning seven years. Our goals include improving soil health/productivity through rotational crops, addressing soil compaction, initially mechanically, but further through selecting deep rooted crops. Deep ripping has questions over its effectiveness in the longer term, and possible damage to soil structure, but can certainly open ground to facilitate deeper rooting of crops/plants immediately following.

Rotational cropping has added potential to increase soil organic matter, an issue we think has deteriorated our dairy land’s productivity over the last fifty years. The benefits of increased organic matter on an organic farm we work with showcase this potential. This organic farm nowadays would out yield many conventional farms and has a per cow milk production average 60% higher than the national average.

Crop root systems deposit organic matter in soils. Likewise, stubble from crops, although nitrogen must be available to breakdown residue or new seedlings will suffer retarded growth until plant residue has been broken down. A clover crop through winter can provide excellent high calcium silage for dry and springing cows, but also increase soil N for the following summer crop. We have measured very high turnip yields following a winter clover crop.

Overseas research has demonstrated reduced weed and pest problems through rotational crop programs. As with antibiotics in treating disease/infections in cows, we will be restricted in the use of these and plant protection chemicals in the very near future. Garden enthusiasts know well that various plants protect and encourage growth in other plants. We need to return our farms to more natural biology, and I’m confident we can do so and increase our profitability.

Calcium is essential for mineral movement in soils, making them available to plants, and for the same reason in cows’ digestive systems. The application of lime to farms has deteriorated dramatically over my lifetime. I suspect this too has reduced our soil’s capacity to support vibrant plant growth, apart from soil pH.

The last twelve months has shocked us all, both farmers and the service industry. Innovation and prosperity almost always rises from the rubble of adversity; and rarely from affluence.

John Lyne is a dairy production specialist with Dairytech Nutrition

Transition appears to be a subject we preach to ad nauseam. However, in the wise words of Dr Tom Overton (Cornell University), we need to shift our view of transition from a time of disease threat to one of production/reproduction opportunity.

The assumption that all is well, based on no, or little clinical milk fever or ketosis, is far from the truth. Any clinical disease at calving is a flag that we have significant sub-clinical issues, and research has verified the financial magnitude of sub-clinical metabolic disease as far more costly. When metabolism is dysfunctional around calving it may not manifest into clinical disease, but sub-clinical disease will reduce production and fertility. Improvements in milk production and fertility are economically significant.

There are large datasets from commercial herds highlighting both the prevalence of sub-clinical disease and its impact on milk and reproductive performance. Research focus on blood calcium status post-calving show cows with sub-optimal blood calcium one week after calving had twice the displaced abomasum rate, produced 2 to 5 litres less milk and 30% decreased conception rates at first service.

Research by Ospina et al, 2010 studied high NETA and BHBA (ketosis indicators) levels in transition cows found that 15% of herds with elevated levels was alarm level and could reduce heifer production by 500 lts and mature cows by 300 lts. Over 71 herds involved in this research, 50% were in excess of 15% affected cows.

Sub-clinical milk fever and ketosis, they usually go together, along with most other transition problems, can be prevented. Anionic lead feeds are a simple answer to sub-clinical milk fever, and managing energy from dry-off to calving will minimise sub-clinical ketosis. Most other transition problems are secondary disease as a result of these two. Both these diseases carry long-term financial consequences.

We all look for the Silver Bullet that will lift our farms profitability. Reality is, transition can well be that silver bullet, but it requires attention to less obvious details. Simple things like a change in forage of the springer cow ration can throw the ration DCAD out significantly, and suddenly we have cows down at worst, but also unknown sub-clinical disease from an equally unknown change in forage potassium level.

Profits won or lost around transition are major due to lactation-long impacts. No other activity on a dairy farm will yield a higher return on time invested. Checking urine pH of springer cows at least weekly and adjusting the anionic lead feed grain fed to restore the correct pH will virtually eliminate sub-clinical milk fever. Checking fresh cow’s milk with a milk keto test strip at day three post-calving and drenching anything in excess of a reading of 100 with propylene glycol will likewise virtually eliminate sub-clinical ketosis. Without these two most common calving related diseases, you will not just lift the bar on potential milk production, but also have given fertility a boost.

The two drivers of farm profit are feed, because it translates to litres and milk dollars, and fertility, because fresh cows convert feed dollars to milk dollars far more efficiently. Carry-over cows and underfeeding are the two greatest legacies of the Australian dairy industry.

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NEB, Immunity and the Domino Effect
There is a direct correlation between Negative Energy Balance (NEB) and Immunity, and individual imbalances, around calving. Imbalance in both energy and immune system are inevitable at calving; the degree of severity will determine the domino effect this has; being the cascade of metabolic and infectious diseases that can be precipitated from these two crucial functions of our calving cow.
As stated in earlier articles, my definition of transition extends from dry-off to pregnancy. From dry-off, the nutritional issues will determine our success in timely pregnancy. Dry-off BCS has been reducing over the last ten years as research correlates higher BCS with poor post-calving feed intakes, especially rate of increase. Hormonally driven milk increase, not being met by feed (energy) intake, and the gap widens in overconditioned dry cows in the first few weeks.
Negative energy balance and immune imbalance are intimately related, and our goal as manages is to minimise the severity and duration of both. Failure to meet energy post-calving leads to sub-optimal immunity and the dominos start falling. Immune function is an energy-hungry machine. If cows are quietly fighting sub-infection while dry, then energy becomes a scarce resource immediately at calving due a massive increase demanded by the mamary system, we’ll have a ‘health’ implosion. This scenario will only amplify the NEB crisis by reducing feed intake at the most critical time. It is well documented, sick cows, either clinical or sub-clinical, lose appetite.
To understand the magnitude of the increase in energy demand at the point of calving, researches have quantified this shift from 680 gm of glucose precalving to 1.8 kgs immediately post-calving. It almost trebles! The liver works overtime converting substrate from rumination to glucose, plus some help from body fat and protein. This is the tripping point: how much from rumination (feed intake), and how much comes from body reserves. As above, the lighter cow at calving will increase feed intake more rapidly than the heavier cow and hence reduce her reliance on conversion of body fat and protein to meet the mamary system’s demand as milk production escalates.
The immune system is already under pressure simply from the physical stress of calving. Any other physical stress factors will only multiply the demand on the immune system. Management can play a significant role here in preparitory minimisation of external stressors to our calving cow. Once energy supply becomes an issue, immunity will not cope with normal bacterial exposure at calving, let alone any preconditions, like mastitis. Retained membrane followed by metritis send the immune system into overload and inability to meet infection outbreaks. Again, all this only multiplies the energy issue by reducing feed intake. Here go the dominos!
We have two lines of health issues from here: infection due to compromised immune function, and metabolic disease due to excessive fat mobilisation, trying to meet the glucose deficiency, creating fatty liver syndrome and soon after, ketosis. Managing energy is the key.

There is a crisis where normal negative energy balance passes the point of no return. The mediators sent out by the immune system to fight infection also cause inflamation. Inflamation is good to a point. Inflamation is crucial in controlling intial bacterial invasion recruiting immune cells to the site of infection. However, imbalance in the immune system will cause excessive inflamation and incomplete killing of bacteria, pain and swelling for the cow, either external or internal.
Inflamation is also very counter to conception. The inflamation in the uterus from a clinical mastitis case will devistate conception or holding of early pregnancies due to physical and chemical changes in uterine mucus. Immune mediators travel via the blood system, so inflamation is systemic.
How do we manage it?
Dry-off in lower BCS than has been customary. Keeping cows milking well up to dry off will enable this. Cows dried off in summer/early autumn can be a problem due to low protein diet at that time of year. It is imperative the dry cow has no weight gain or loss while dry. Either will precipate the reduced feed intake post-claving. Controlling the dry cow diet is easy during late summer early autumn when pasture intake is not a problem. Good quality adlib silage will do the job nicely.
As discussed in a previous article, 30% to 40% clover must be our pasture goal to meet cows calcium need on top of supplementation in bale feed. Silage made from this pasture mix will also meet the dry cow’s calcium need with significant benefits to immunity, milk protein production and fertility. Controlling energy intake in dry cows once pasture is available requires more monitoring. Adlib hay rings and strip grazing calculating pasture energy intake by monitoring hay consumption and adjusting strip width, is as close as we can get in a grazing system.
The springer cow diet is, as above, plus 3 or 4 kgs of a good lead feed grain mix including anionic salts. Again, it is imperative we monitor/calculate energy intake. DCAD (Dietary Cation/Anion Difference) is critical to springer cows. This is easily done by checking urine pH several times each week. A pH of 5.5 to 6.5 with Jerseys at the lower end and holsteins toward the other end. Drenching cows at calving with propylene glycol is very successful in mitigating ketosis. We have several clients with computer rotary dairys who administer small doses of propylene glycol to fresh cows for 20 days via the computer.
Ketosis status is easily measured with a Milk Keto Test Strip. We encourage all cows be checked at day three for ketosis. Any cow with a reading above 100, treat with propylene glycol: 200 to 400 ml dependant on the severity of the reading. Recheck three days later and retreat as above.
If we’ve been successful with both dry cow and springer cow nutrition, including mineral supplementation, both trace and macro, we’ll avoid most of the problems, metabolic and infection. Our cow is now capable of reaching her genetic potential for milk production, and, contrary to popular belief, most likely to become pregnant in a timely manner. The highest producing cows in the USA (15,000 lts in 305 days), have the highest MP%’s, and the highest fertility.