The effects on ewes and lambs of grazing pasture containing differing levels of nitrate‐nitrogen

Dickson, I. A.; Macpherson, Allan

doi:10.1111/j.1365-2494.1976.tb00785.x

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…The level of NO3-N in forage crops that can be considered toxic to livestock has not been clearly established but it would appear from the literature that concentrations above 014% in the DM can be considered potentially dangerous (Wright and Davidson, 1964). In some recent studies, however, Phipps (1975) and Dickson and Macpherson (1976) failed to observe any detrimental effects on animal health or production when herbage contained as much as 076% NO3-N in the DM. Nowakowski and Gasser (1967) reported that an application of 200 kg ha"' N as ammonium sulphate to grass pasture resulted in a NO3-N concentration in the DM of 0-189% which was reduced to 0 069 % by application of a nitrification inhibitor (2-chloro-6-trichloromethyl pyridine).…”

Section: Introductionmentioning

confidence: 99%

The effects of rates of application and sources of nitrogen on nitrate concentration in oat forage

Joshi

Prasad

1977

Grass and Forage Science

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A field experiment was conducted during the winter seasons of 1972-73 and 1973-74 to study the effects of rates of application (0, 100, 200 kg ha"') and sources of nitrogen (ammonium sulphate, calcium ammonium nitrate, urea, sulphur-coated urea and sulphathiazole-treated urea) on nitrate-N concentration in oat {Avena sativa L.) forage. N application increased the nitrate-N concentration, the effects being more marked when the rate was increased from 100 to 200 kg ha"' than when it was raised from 0 to 100 kg ha" •. The highest nitrate-N concentration in the dry matter ( > 0-16%) was obtained when calcium ammonium nitrate was applied at 200 kg ha"' N. Sulphur-coated urea gave the lowest nitrate-N concentration. In one year treatment of urea with sulphathiazole reduced nitrate-N concentration in oats forage.

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Section: Introductionmentioning

confidence: 99%

The effects of rates of application and sources of nitrogen on nitrate concentration in oat forage

Joshi

Prasad

1977

Grass and Forage Science

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“…The lack of consistent differences between treatments may be due to factors such as N contributions from the soil and varying climatic conditions (Dickson & Macpherson, 1976;Wilson, 1981). The soluble N fraction, rate of degradation of the potentially degradable fraction and effective N degradability of herbage decreases with advancing stage of re-growth (Van der Merwe, 1993).…”

Section: Resultsmentioning

confidence: 99%

Performance responses of lambs of various ages to Italian ryegrass (<i>Lolium multiflorum</i>) fertilized with various levels of nitrogen

Villiers¹,

Ryssen²

2001

SA J. An. Sci.

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Italian ryegrass (Lolium multiflorum cv. Midmar) is often fertilized with high levels of nitrogen (N) in order to ensure maximum dry matter (DM) yields. This practice also increases the N content of herbage. This study was conducted to determine whether differences in the nitrogen (N) content of Italian ryegrass would have an effect on the performance of South African Mutton Merino lambs. Fertilizer levels of 100, 200, 400, 600 or 800 kg N/ha were applied to the pastures in order to produce herbage containing varying concentrations of N. Nitrogen fertilization increased the total N and nitrate-N in the plant material and decreased non-structural carbohydrate concentrations. An increase in rumen ammonia-N concentration with increasing pasture N concentration was observed in twelve and four-month-old lambs. A quadratic relationship was found to exist between the N content of ryegrass and DM intake for twelve-month-old lambs, and a negative linear relationship was observed for four-month-old lambs. A quadratic relationship was observed between the N content of ryegrass and average daily gain for lambs of both age groups. The equations derived in this study illustrate the potentially negative effects of high concentrations of N and nitrate-N in Italian ryegrass on intake and growth rate of lambs.

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“…Later in the grazing period, the forage contained ~3,500 mg NO 3 -N/kg DM, yet no toxicity signs were observed and methemoglobin concentrations were reported to be negligible. Similarly, lactating ewes rotationally grazing on potentially toxic perennial ryegrass ( Lolium perenne ) pastures had no issues ( Dickson and Macpherson, 1976 ). The nitrate content of the pastures ranged from 300 to 6,700 mg NO 3 -N/kg DM.…”

Section: Introductionmentioning

confidence: 99%

Is it time to rethink our one-size-fits-all approach to nitrate toxicity thresholds in forages?

Reynolds

Drewnoski

2022

Translational Animal Science

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Annual forages provide a valuable grazing resource for cattle producers; however, annuals are prone to accumulating nitrate and have the potential to cause nitrate toxicity.. Although these forages pose a risk of containing high nitrate concentrations, they can be a high-quality feed source. Understanding the factors that affect the potential for toxicity when using these forages is important to help nutritionists and producers make management decisions. This review describes the previous research, current guidelines for nitrate toxicity and the potential for improvement in our current recommendations. Current extension toxicity guidelines appear to be founded primarily on drenching based studies and overestimate the nitrate toxicity potential of forages. Recommendations need to account for multiple factors that affect the threshold for toxicity. There is evidence that fresh forages have a lower risk of toxicity because of slower release of nitrate into the rumen and a slower rate of DM intake. Increased dietary energy and sulfur content reduce the potential for toxicity. Microbial adaptation can reduce the risk and allow use of potentially toxic forages. These factors should influence feeding recommendations. However, there is currently not enough data available to establish new guidelines which account for these main factors. Thus, there is a need for renewed research in this area. The limited number of studies grazing elevated nitrate forages seems to suggest that there is less risk in grazing situations, especially if animals graze selectively. There is a need to develop guidelines for nitrate toxicity and management recommendations when grazing. To accomplish this there is a need for more studies to evaluate risk of toxicity in grazing situations. These grazing studies need to evaluate the effects of nitrate concentration, forage quality, and grazing management on the potential for nitrate toxicity. While the conservative guidelines that are currently in use reduce risk of nitrate toxicity, they may also cause a significant increase in feed costs for producers.

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The effects on ewes and lambs of grazing pasture containing differing levels of nitrate‐nitrogen

Cited by 4 publications

References 8 publications

The effects of rates of application and sources of nitrogen on nitrate concentration in oat forage

The effects of rates of application and sources of nitrogen on nitrate concentration in oat forage

Performance responses of lambs of various ages to Italian ryegrass (<i>Lolium multiflorum</i>) fertilized with various levels of nitrogen

Is it time to rethink our one-size-fits-all approach to nitrate toxicity thresholds in forages?

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