The development of a substantial beef feedlot sector (total capacity 1.3 million head, January 2019) and access to established or opportunity lamb feedlots, facilitates the managed sale of young livestock during droughts at reasonable prices. This should continue to change the way livestock are managed during future droughts if market forces are allowed to exert their effects. This paper summarises lessons learned from this and previous droughts and proposes guidelines for more efficient future drought management.
Observations from the 2017 to 20?? Drought and Previous Droughts
The Nutrient Requirements of Breeding Stock: A large proportion of producers are unable to calculate the energy requirements of breeding stock. Previous initiatives to educate producers on nutrient requirements in terms of kilograms (kg) of dry matter are demonstrably inadequate because of variation in feedstuff nutrient density and moisture. Frequently, cattle in particular are underfed during droughts. The lack of appreciation of the shortfall in energy intake has in some circumstances been exacerbated by an inappropriate preoccupation with protein and a lack of understanding of the different roles of protein and energy (the contribution of protein to energy metabolism notwithstanding).
Earlier Weaning: Increased production and profitability in response to earlier weaning (at approximately 3 months compared with 6 to 7 months) have been reported for a range of production systems in southern Australia (Tathum et al., 2004) and throughout the world, including Brazil (Vaz et al., 2014; Vaz et al., 2010), Cuba (Simeone and Beretta, 2016), Mexico (Ibarra Flores et al., 2011) and the U.S. (Kruse et al., 2007). Some studies have not found positive effects (Rasby et al., 2016; Warner et al., 2015) but these interventions were not accompanied by a reallocation of resources through increased stocking rate or increased nutrient density of the diet offered to the young growing stock. In summary, earlier weaning must be matched with greater harvest of the feed base by growing animals to be profitable or with savings in feed costs if cows no longer require supplementation to achieve target body condition.
The energetic efficiency with which dairy cows convert forage energy into milk is approximately 60% (Moe, 1981) and this figure is likely lower in beef cows. The energetic efficiency with which milk is used for live weight gain in pre-ruminant calves is approximately 90% because it is directly digested in the abomasum (the "true stomach": Moran, 2012). This is considerably higher than the energy use efficiency of pasture for live weight gain in ruminant calves of approximately 60% (Moran, 2012), which approximates that of milk production by cows on forage. Despite the high efficiency of use of milk energy for calf growth, the multiplicative effect of the efficiency of forage energy use by the cow results in an efficiency of approximately 60% x 90% = 54% for the conversion of the forage energy consumed by the cow into calf live weight gain. However, with the developing predominance of the rumen in the ruminant calf, the efficiency of use of energy from milk decreases substantially to be as low as 63% (Johnson, et al., 1972). This then reduces the efficiency of energy utilisation from forage eaten by a cow to feed milk to a ruminant calf to 60% x 63% = 38%. The explanation for the decrease in digestive efficiency of milk in the developing ruminant lies in the loss of the oesophageal reflex which diverts milk away from the rumen and fermentation by microbes, directly into the abomasum with clot formation and simple digestion. Most of the anatomical and functional transformation from pre-ruminant to ruminant with calves on nutrient dense forage has occurred by two months of age and progressive loss of the oesophageal reflex accompanies this (Ensminger, 1990). In addition, it is likely that flooding of the abomasum with fermented forage interferes with clot formation even in calves with a persistent strong oesophageal reflex. To summarise, it is energetically more efficient to feed high quality forage to a young ruminant than to a cow to feed the young ruminant, and this effect is established by the time the calf is two to three months old.
In addition to the energetic efficiency of earlier weaning, there are managerial factors that can enhance the positive effects on productivity and profitability. These are: the reallocation of feed resources to growing animals; more accurate sustained management of the condition score of breeders; and avoidance of the wasteful deposition of fat in breeders. These effects are enhanced by an increase in energy partitioning in the cow away from milk and into body tissue deposition with advancing lactation (Xue et al., 2011). Thus, earlier weaning converts more of the available feed energy into saleable beef by increasing the growth rate of young stock, increasing the sustainable number of breeders, allowing more opportunistic trading, or a combination of all these. Despite the obvious energetic and production advantages of earlier weaning, there are still large numbers of enterprises that pursue high weaning weights as an ill-conceived target, rather than focussing on turnoff per hectare. Whilst drought forces some producers to wean earlier, most return to their previous practices once the drought is over. More efficient management of drought, and increased beef production efficiency outside of drought, require weaning to be a planned event where disease prevention procedures are implemented and the nutritional requirements of the weaners are met.
Mineral and Vitamin Deficiencies: Confusion amongst producers abounds with respect to meeting the mineral and vitamin requirements of livestock. The requirement for calcium with cereal grain supplements is not universally recognised, but some producers have utilised commercial anionic salts formulated to reduce the incidence of periparturient hypocalcaemia in dairy cows either unnecessarily in beef cows, or counterproductively in multiple bearing ewes. There are trace element products that have been and are being successfully marketed for routine use in regions free of trace element deficiencies which do little more than result in expensive urine. Routine injections of combined vitamin ADE are administered to many stock even when they have been on green feed during non-winter months. Unfortunately, deficiencies of vitamins A and E need to be addressed in stock that have not had green feed for 6 months or more and this application is frequently missed. Further, vitamin D responsive lameness and rickets has been reported in lambs on grazing cereals south of Young during the last 4 years, which is north of the previously recognised line of insufficient winter incident ultraviolet light (35°S; CSIRO, 2007, 1990).
Opportunity Lamb Feeding – Ruminal Acidosis: Whilst for many years there have been self-feeder based opportunity lamb feedlots where concentrates (primarily cereal grain) are fed separately to roughage, the current drought has seen a proliferation of these. Further, many are of much larger scale than previous facilities, facilitated by the use of automated concentrate delivery systems that eliminate the need for machinery filling of feeder bins. Feeding systems where cereal grains are provided separate to roughage chronically predispose lambs to ruminal/lactic acidosis. The acidosis risk is frequently not appreciated where producers have a history of trail feeding limited grain allocations of supplementary feed in paddocks, and where drought affected high protein/low starch grains are initially fed. With production feeding of lambs, where high growth rates and therefore high feed intakes are targeted, and where higher starch grains are fed, severe production losses and high mortality rates due to ruminal/lactic acidosis have been recorded with grain only feeder bin systems.
Opportunity Lamb Feeding – Urolithiasis: It is important to recognise that there is more to the occurrence of urolithiasis than elevated dietary intake of macrominerals such as P and Mg. There are generally no toxicities from macrominerals alone, with problems arising from negative interactions with other minerals. There is no known P toxicity per se (Ensminger, 1990), however, excess dietary phosphorus can decrease calcium (Ca) absorption. Also, when the dietary P concentration is high relative to Ca, urinary calculi can be formed, especially in ruminants (Ensminger, 1990). Dietary P concentration should not be more than 6 g/kg DM (Jones and Meisner, 2009). Blood calcium concentration is normally controlled by small intestinal absorption which represents an interaction between dihydroxy-vitamin D3, P and Ca intake. Similar to P, there is no known Ca toxicity per se, with the dietary Ca concentration relating primarily to the required Ca:P ratio. Whilst the target of approximately 2:1 is ideal, Ensminger (1990) notes that very broad ratios up to 7:1 are satisfactory for ruminants. Spontaneous toxicities for Mg have not been reported (Ensminger, 1990), but excess Mg can interfere with Ca and P metabolism. The NRC (National Research Council, 1985) recommends a maximum dietary Mg concentration of 5 g/kg DM, whilst Jones and Meisner (2009) recommend a maximum Mg concentration of 6 g/kg for the prevention of struvite calculi formation.
If elevated concentrations of macrominerals alone contributed to an increased incidence of urolithiasis, we could expect to see a chronically elevated incidence on grazing lucerne in addition to a range of widely used commercial products (Table 1).
Table 1. Dietary concentrations of macrominerals in commercially available lamb finishing pellets and grazing lucerne.
|Product||Concentration (g/kg dry matter)|
|Grazing Lucerne – early vegetative (NSW DPI)||16||4||2.6|
|Weston Milling Farmyard Finisher Nuts||17 minimum||5 minimum||3.5 minimum|
|Coprice Sheep Pellets||15 minimum||7.5 minimum||Not quoted|
|Riverina Lamb Feedlot Pellets||10 minimum||4 minimum||Not quoted|
|Riverlea Slingshot Lamb Finisher Pellets||11.6||4.2||2.1|
|Milne EasyOne Pellets||11.5||3.3||2.1|
Note that the macromineral concentrations in the commercial pellets manufactured by Weston, Coprice and Riverina are minima, and it can therefore be assumed that the concentrations will frequently be higher than the concentrations in Table 1.
Other potential predisposing factors for the occurrence of urolithiasis are: restricted water intake (urolithiasis is more commonly a problem during winter); alkaline water with high mineral concentration (particularly Mg); the use of feed additives such as NaHCO3 and CaCO3 at high inclusion rates; high dietary inclusion of sorghum which has higher concentrations of the low molecular weight peptides that form the organic matrix to which urinary salts adhere; and vitamin A deficiency due to increased shedding of bladder endothelium.
The short feeding duration of lambs, with most programmes turning lambs off within 6 weeks, likely eliminate most problems due to forming uroliths. The incidence of urolithiasis has been high in lambs fed for prolonged periods due to feedlot placement at low BW (body weight) and low BCS (body condition score). This can occur under drought conditions where low BW weaners are initially intensively drought fed, and then fed on for a prolonged period to reach marketable weights.
Confusion Between Supplementary and Complementary Feeding: The distinction between supplementary and complementary feeding is simple if rumen function is understood. Supplementary feeds have a high substitution rate and effectively reduce stocking rate. Complementary feeds provide energy and nitrogen to the rumen microbes, thereby allowing them to ferment a much higher proportion of lower digestibility feeds which increases available ME (metabolisable energy) and increases rumen outflow rate, which thereby increases intake. Complementary feeds (eg. urea-molasses, corn steep liquor, condensed distillers syrup, protein meal-urea mixes etc.) should not be provided to stock that have limited available forage dry matter (eg. senesced pastures, stubbles). In this situation supplementary feeds are required, but low quality supplementary feeds (eg. baled straw or tailings) can provide more MJ (megajoules) of ME to the stock if complementary feeds are also provided.
Plant Toxicoses: The bare ground of droughts results in the proliferation of many weed species and under conditions of limited feed availability these will be grazed to a greater extent than when feed is plentiful. Regional and seasonal variations in these potential toxicities require vigilance and awareness of clinical sign trigger points for stock removal from the offending paddocks.
Drought Relief? Despite decades of various governments paying lip service to the reform of drought assistance, whenever a major drought occurs (approximately once a decade for the last 231 years), producer representative bodies request direct financial assistance until it is forthcoming. Subsidies for fodder and freight distort markets and low interest loans and direct payments prolong the life of unviable agricultural businesses and remove the competitive advantage of better managed businesses that have adequately identified and planned for the business risk of drought.
Proposals for More Efficient Drought Management
Nutrition and Financial Literacy: Every livestock producer should have a functional understanding of how the rumen works. For older producers this will require informal training at producer field days and workshops. Younger producers should pursue formal tertiary training in both nutrition and finance. Our expectations of the standard of education of livestock producers, running extremely complex biological systems frequently worth millions of dollars, is low. Further, even where tertiary training in these disciplines has been completed, it appears our universities often fail to turn out proficient functional managers of biology and finance. In addition, this nutrition and financial literacy should be enhanced by payment for independent expertise in both areas. This means that livestock production and health advisors should be proficient in costing out options for solving a given nutrition or health problem so these can be presented to the producer for an objective decision. These simple partial budgets and sensitivity analyses are outside the remit of accountants because they require an understanding of both the biological and financial inputs and must therefore be provided by veterinarians and nutritionists. The model for payment for advice already exists in agronomy, although the fees have been obscured over recent years by the widespread employment of agronomists by rural merchandisers.
The engagement of professional advice in nutrition and health and a fundamental understanding of these by producers would allow them to challenge management changes such as earlier weaning. This provides an opportunity to work objectively through the production and financial benefits to carry the case for change. Further, greater nutrition and health knowledge amongst producers and the use of outside expertise would filter the myriad products they constantly have marketed to them to drive the adoption of cost-effective inputs and eradicate the waste of unproven, unnecessary, or detrimental products and practices.
Feed Base Triggers and Recovery Pasture Planning: The establishment of available pasture herbage mass triggers, related to time of year/season, with consequent destocking, requires interaction between nutritionists and agronomists. The cost of pasture depletion carries over some years after a drought. Under prolonged dry conditions, the current drought has shown that perennial pasture plants can die out even with the preservation of generous pasture dry matter residuals. On the upside, droughts also provide opportunities for longer term weed control and pasture renovation programmes. It is essential to recognise that the beef feedlot sector, and to a lesser extent, intensive lamb feeding, ensure that producers are always guaranteed a sale avenue for young stock and this should be utilised as soon as practical once pasture base triggers are hit in a dry time. With breeding stock, there is often a counter argument that "you won’t be able to find stock like these when the drought breaks" if the breeding herd is sold down in response to drought. Considering the lack of information on the genetic merit of most commercial herds and flocks, this assertion is frequently unsupported. Inevitably, the cost of replacement stock is elevated at the end of a drought. This requires the producer to be flexible in the short term on the class of stock purchased (possibly to trade) or even enterprise choice.
Calendars of Procedures and Inputs (with variability): Management of the complex biological and financial systems of animal agriculture is made much easier with the forward scheduling of an annual calendar which can include decision nodes related to season and feed availability.
Identification of Drought Risk and Steps to Address that Risk: Once the inevitable risk of drought in Australia is identified, there are multiple options available to address that risk. These are: off-farm income or investment in liquid off-farm assets (shares, bonds, cash); stored feeds (pits of silage, silos of grain); and investment in irrigated land.
Drought has been a regular part of Australian agriculture since 1788 and always will be. Consistent with our expectations of the directors of companies, the managers of complex livestock production businesses should identify risk and act to minimise it. Better management of drought requires improved nutrition and financial literacy by producers and a preparedness to pay for independent advice. Livestock businesses that invest in drought preparedness are disadvantaged by financial assistance given to those producers who do not invest in drought preparedness, and this must cease for the industry as a whole to better manage this recurring risk. Otherwise, we will be discussing the same topic in ten years time.