Whole-animal nitrogen balance in cattle.

Firkins, J.L.; Reynolds, Chris

doi:10.1079/9780851990132.0167

Cited by 21 publications

(9 citation statements)

References 110 publications

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“…Although MNE is mainly driven by the dietary CP concentration (Huhtanen and Hristov, 2009), other covariates may influence the N partitioning, such as the dietary energy supply (Firkins and Reynolds, 2005) or the type of absorbed energy-yielding nutrients (Leiva et al, 2000). Results from literature concerning the effect of the dietary carbohydrate composition (CHO; starch v. fiber) on milk protein yield are variable and inconsistent Khalili and Sairanen, 2000;Hristov and Ropp, 2003), likely because the effect of the CHO is often confounded with the total amount of energy consumed.…”

Section: Introductionmentioning

confidence: 99%

Dietary carbohydrate composition modifies the milk N efficiency in late lactation cows fed low crude protein diets

Cantalapiedra-Hijar

Peyraud

Lemosquet

et al. 2014

Animal

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Nitrogen emissions from dairy cows can be readily decreased by lowering the dietary CP concentration. The main objective of this work was to test whether the milk protein yield reduction associated with low N intakes could be partially compensated for by modifying the dietary carbohydrate composition (CHO). The effects of CHO on digestion, milk N efficiency (milk N/N intake; MNE) and animal performance were studied in four Jersey cows fed 100% or 80% of the recommended protein requirements using a 4 × 4 Latin square design. Four iso-energetic diets were formulated to two different CHO sources (starch diets with starch content of 34.3% and NDF at 32.5%, and fiber diets with starch content of 5.5% and NDF at 49.1%) and two CP levels (Low = 12.0% and Normal = 16.5%). The apparent digestible organic matter intake (DOMI) and the protein supply (protein digestible in the small intestine; PDIE) were similar between starch and fiber diets. As planned, microbial N flow (MNF) to the duodenum, estimated from the urinary purine derivatives (PD) excretion, was similar between Low and Normal CP diets. However, the MNF and the efficiency of microbial synthesis (g of microbial N/kg apparently DOMI) were higher for starch v. fiber diets. Milk and milk N fractions (CP, true protein, non-protein N (NPN)) yield were higher for starch compared with fiber diets and for Normal v. Low CP diets. Fecal N excretion was similar across dietary treatments. Despite a higher milk N ouput with starch v. fiber diets, the CHO modified neither the urinary N excretion nor the milk urea-N (MUN) concentration. The milk protein yield relative to both N and PDIE intakes was improved with starch compared with fiber diets. Concentrations of β-hydroxybutyrate, urea and Glu increased and those of glucose and Ala decreased in plasma of cows fed starch v. fiber diets. On the other hand, plasma concentration of albumin, urea, insulin and His increased in cows fed Normal compared with Low CP diets. This study showed that decreasing the dietary CP proportion from 16.5% to 12.0% increases and decreases considerably the MNE and the urinary N excretion, respectively. Moreover, present results show that at similar digestible OM and PDIE intakes, diets rich in starch improves the MNE and could partially compensate for the negative effects of Low CP diets on milk protein yield.Keywords: milk N efficiency, dairy cow, carbohydrate composition, dietary CP concentration, N pollution ImplicationsThe possibility of binding dairy incomes to environmentally friendly practices would add more interest to formulating diets with a high efficiency of nutrient utilization. A reduction of N emissions from dairy cows can be readily achieved by decreasing the CP concentration of diets. In order to minimize the negative impact of low N diets on milk protein yield, the efficiency of N utilization can be improved by replacing a percentage of dietary fiber by starch at iso-energetic concentrations. Lessening the dietary CP concentration and changing the carbohydrate composition can be tw...

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Section: Introductionmentioning

confidence: 99%

Dietary carbohydrate composition modifies the milk N efficiency in late lactation cows fed low crude protein diets

Cantalapiedra-Hijar

Peyraud

Lemosquet

et al. 2014

Animal

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“…Elevated microbial N capture in the rumen when more energy substrates are available for microbes may reduce net NH 3 production and consequently urea excretion, but will increase urine losses of nucleic acid N synthesized as part of microbial biomass production (Tamminga, 1992). Detrimental effects of large amounts of fermentable carbohydrates on ruminal pH and fibre degradation may occur (Firkins and Reynolds, 2005;Dijkstra et al, 2012), reducing efficiency of conversion of feed into milk or meat. Therefore, diets should be balanced carefully.…”

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confidence: 99%

“…NH 3 is produced by microorganisms in the rumen and hindgut, as well as by catabolism of AAs and other N-containing substrates in intermediary metabolism. In beef and dairy cattle, net urea-N release by the liver accounts for on average 0.65 of increments in N intake (Firkins and Reynolds, 2005). Lapierre et al (2005) reported that, largely dependent upon the interaction between N and energy supply, on average 0.47 (range 0.09 to 0.81) of hepatic ureagenesis returned to the gut via the portal drained viscera, the remainder being excreted mainly in urine.…”

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confidence: 99%

Diet effects on urine composition of cattle and N2O emissions

Dijkstra

Oenema

Groenigen

et al. 2013

Animal

302

215

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Ruminant production contributes to emissions of nitrogen (N) to the environment, principally ammonia (NH 3 ), nitrous oxide (N 2 O) and di-nitrogen (N 2 ) to air, nitrate (NO 3 2 ) to groundwater and particulate N to surface waters. Variation in dietary N intake will particularly affect excretion of urinary N, which is much more vulnerable to losses than is faecal N. Our objective is to review dietary effects on the level and form of N excreted in cattle urine, as well as its consequences for emissions of N 2 O. The quantity of N excreted in urine varies widely. Urinary N excretion, in particular that of urea N, is decreased upon reduction of dietary N intake or an increase in the supply of energy to the rumen microorganisms and to the host animal itself. Most of the N in urine (from 50% to well over 90%) is present in the form of urea. Other nitrogenous components include purine derivatives (PD), hippuric acid, creatine and creatinine. Excretion of PD is related to rumen microbial protein synthesis, and that of hippuric acid to dietary concentration of degradable phenolic acids. The N concentration of cattle urine ranges from 3 to 20 g/l. High-dietary mineral levels increase urine volume and lead to reduced urinary N concentration as well as reduced urea concentration in plasma and milk. In lactating dairy cattle, variation in urine volume affects the relationship between milk urea and urinary N excretion, which hampers the use of milk urea as an accurate indicator of urinary N excretion. Following its deposition in pastures or in animal houses, ubiquitous microorganisms in soil and waters transform urinary N components into ammonium (NH 4 1 ), and thereafter into NO 3 2 and ultimately in N 2 accompanied with the release of N 2 O. Urinary hippuric acid, creatine and creatinine decompose more slowly than urea. Hippuric acid may act as a natural inhibitor of N 2 O emissions, but inhibition conditions have not been defined properly yet. Environmental and soil conditions at the site of urine deposition or manure application strongly influence N 2 O release. Major dietary strategies to mitigating N 2 O emission from cattle operations include reducing dietary N content or increasing energy content, and increasing dietary mineral content to increase urine volume. For further reduction of N 2 O emission, an integrated animal nutrition and excreta management approach is required.Keywords: nitrogen, urine, cattle, nitrous oxide, mitigation ImplicationsCattle contribute to global warming through emission of nitrous oxide (N 2 O) from urine and faeces. Urinary nitrogen (N) is much more susceptible to gaseous losses than faecal N. To reduce urinary N excretion and N 2 O emission and improve N efficiency of cattle, dietary levels of N should be decreased and an optimal balance between N and energy substrates in the diet should be aimed at. Increasing urine volume by increased dietary mineral contents appears a promising N 2 O mitigation strategy, particularly in pasture. Further reduction of effective mitigation strategies...

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“…Kebreab et al (2001) proposed a predictive model in which cattle with an intake of 500 g of N d -1 would have approximately 80 % of total dietary nitrogen excreted in urine. Certain factors can affect the utilization of N by ruminants, such as dietary protein concentration, nitrogen composition of the protein, their interaction with the nutrients (Firkins and Reynolds, 2005), degradability and energy status of the animals (Kebreab et al, 2002). The inclusion of monensin may change the metabolic path in ruminant digestion, improve the protein absorption in the small intestine (Russell and Strobel, 1989) and increase nitrogen retention in lambs (Joyner et al, 1979).…”

Section: Discussionmentioning

confidence: 99%

Low doses of monensin for lambs fed diets containing high level of ground flint corn

Polizel

Martins

Miszura

et al. 2021

Sci. agric. (Piracicaba, Braz.)

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Two experiments were proposed to evaluate the addition of monensin for lambs fed diets containing a high level of mature ground flint corn. The experimental diets were as follows: no inclusion of monensin (M0) and inclusion of 8 (M8), 16 (M16) and 24 mg kg-1 of monensin (M24). In experiment 1, eight cannulated wethers were divided into a double 4 × 4 Latin square experimental design to evaluate nutrient digestibility, plasma parameters and rumen fermentation. The experiment lasted 112 days, divided into four periods of 28 days each. In experiment 2, ninety-two lambs were used in a randomized block design to evaluate the performance over 56 days. In experiment 1, doses of monensin had no effect on nutrient intake (p ≥ 0.07) and digestibility (p ≥ 0.09). There was a quadratic effect for acetate molar proportion (p = 0.01), acetate to propionate ratio (p = 0.04) and rumen pH (p < 0.01). However, there was no effect on the molar proportion of propionate and butyrate. The monensin decreased linearly the total SCFA concentration (p < 0.01). The inclusion of monensin increased glucose (p < 0.01) and decreased lactate concentration in plasma (p = 0.05). In experiment 2, monensin decreased dry matter intake (p = 0.04). However, there was a quadratic effect for average daily gain (p = 0.03) and feed efficiency (p < 0.01), with the greatest values observed for the M8 diet. Thus, the inclusion of 8 mg kg-1 of dry matter diet (DM) improves ruminal fermentation and plasma parameters, resulting in greater growth performance in lambs.

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Whole-animal nitrogen balance in cattle.

Cited by 21 publications

References 110 publications

Dietary carbohydrate composition modifies the milk N efficiency in late lactation cows fed low crude protein diets

Dietary carbohydrate composition modifies the milk N efficiency in late lactation cows fed low crude protein diets

Diet effects on urine composition of cattle and N2O emissions

Low doses of monensin for lambs fed diets containing high level of ground flint corn

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