Critical analysis of N balance experiments with lactating cows

Spanghero, M.; Kowalski, Z.M.

doi:10.1016/s0301-6226(97)00138-3

Cited by 119 publications

(132 citation statements)

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“…As pointed out by Cheng et al (2011), the nitrogen balance technique is difficult to implement and often leads to overestimations of N retention. In a meta-analysis, Spanghero and Kowalski (1997) recorded an average N balance of 39 g/day (ranging from −57 to 205 g/day), representing 8% of N intake and 1/3 of N contained in milk. More recently, Klevenhusen et al (2010) reported N balances of up to 26% of N intake (maize diet, 21% CP), and even if the average value reported in the review of Spek et al (2013) is only 2% of N intake (for EU trials), the high standard deviation of 31 (n = 68) suggests high variations.…”

Section: Edouard Hassouna Robin and Faverdinmentioning

confidence: 99%

“…In contrast, underestimation of faecal N by incomplete collection of material or volatile losses of ammonia during collection and subsequent drying of the samples could be important (e.g. −15% N in faecal samples after drying compared with fresh faeces; Spanghero and Kowalski, 1997). Echoing the words of Reynolds and Kristensen (2008), mysteries of N balance still need to be solved today.…”

Section: Edouard Hassouna Robin and Faverdinmentioning

confidence: 99%

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Low degradable protein supply to increase nitrogen efficiency in lactating dairy cows and reduce environmental impacts at barn level

Edouard

Hassouna

Robin

et al. 2016

animal

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Generally, <30% of dairy cattle's nitrogen intake is retained in milk. Large amounts of nitrogen are excreted in manure, especially in urine, with damaging impacts on the environment. This study explores the effect of lowering dietary degradable nitrogen supplies -while maintaining metabolisable protein -on dairy cows' performance, nitrogen use efficiency and gas emissions (NH 3 , N 2 O, CH 4 ) at barn level with tied animals. Two dietary N concentrations (CP: 12% DM for LowN; 18% DM for HighN) were offered to two groups of three lactating dairy cows in a split-plot design over four periods of 2 weeks. Diets were formulated to provide similar metabolisable protein supply, with degradable N either in deficit or in excess (PDIN of 84 and 114 g/kg DM for LowN and HighN, respectively). Cows ingested 0.8 kg DM/day less on the LowN diet, which was also 2.5% less digestible. Milk yield and composition were not significantly affected. N exported in milk was 5% lower (LowN: 129 g N/day; HighN: 136 g N/day; P < 0.001) but milk protein yield was not significantly affected (LowN: 801 g/day; HighN: 823 g/day; P = 0.10). Cows logically ingested less nitrogen on the LowN diet (LowN: 415 g N/day; HighN: 626 g N/day; P < 0.001) resulting in a higher N use efficiency (N milk/N intake; LowN: 0.31; HighN: 0.22; P < 0.001). N excreted in urine was almost four times lower on the LowN diet (LowN: 65 g N/day; HighN: 243 g N/day; P < 0.001) while urinary urea N concentration was eightfold lower (LowN: 4.6 g/l; HighN: 22.9 g/l; P < 0.001). Ammonia emission (expressed in g/h in order to remove periods of the day with potential interferences with volatile molecules from feed) was also lower on the LowN diet (LowN: 1.03 g/h per cow; HighN: 1.25 g/h per cow; P < 0.05). Greenhouse gas emissions (N 2 O and CH 4 ) at barn level were not significantly affected by the amount of dietary N. Offering low amounts of degradable protein with suitable metabolisable protein amounts to cattle improved nitrogen use efficiency and lowered ammonia emissions at barn level. This strategy would, however, need to be validated for longer periods, other housing systems (free stall barns) and at farm level including all stages of manure management.

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Section: Edouard Hassouna Robin and Faverdinmentioning

confidence: 99%

Section: Edouard Hassouna Robin and Faverdinmentioning

confidence: 99%

Low degradable protein supply to increase nitrogen efficiency in lactating dairy cows and reduce environmental impacts at barn level

Edouard

Hassouna

Robin

et al. 2016

animal

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“…This estimation was not realistic for goats fed on around 2000 g of DM/day, and also inconsistent with the weight change data (0 g/day on average). Spanghero and Kowalski (1997) suggested that overestimation of retained N is commonly observed in NB studies. The possible sources of errors for high N retention value include the incomplete collection of materials, volatile N losses from faeces and urine as well as scurf and dermal losses.…”

Section: N Metabolismmentioning

confidence: 99%

The effect of dietary water soluble carbohydrate to nitrogen ratio on nitrogen partitioning and isotopic fractionation of lactating goats offered a high-nitrogen diet

Cheng

Edwards

Dewhurst

et al. 2016

Animal

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The objective of this study was to investigate the relationship between nitrogen (N) partitioning and isotopic fractionation in lactating goats consuming diets with a constant high concentration of N and increasing levels of water soluble carbohydrate (WSC). Eight lactating goats were offered four different ratios of WSC : N in the diet. A two-period incomplete cross-over design was used, with two goats assigned to each treatment in each period. N balance measurements were conducted, with measurement of feed N intake and total output of N in milk, faeces and urine. Treatment, period and infusion effects were tested using general ANOVA; the relationships between variables were analysed by linear regression. Dietary treatment and period had significant effects on dry matter (DM) intake (g/day). DM digestibility (g/kg DM) and N digestibility (g/kg N) increased as the ratio of WSC : N increased in the diet. No treatment effect was observed on milk urea N concentration (g/l) or urinary excretion of purine derivatives (mM/day). Although dietary treatment and period had significant effects on N intake, the change of N intake was small; no effect was observed for N partitioning among faeces, milk and urine. Milk, plasma and faeces were enriched in 15 N compared with feed, whilst urine was depleted in 15 N relative to feed. No significant relationship was established between N partitioning and isotopic fractionation. This study failed to confirm the potential to use N isotopic fractionation as an indicator of N partitioning in dairy goats when diets provided N in excess to requirements, most likely because the range of milk N output/N intake and urinary N output/N intake were narrow.Keywords: nitrogen utilisation, urea nitrogen, stable isotopic discrimination, dairy goats Implications Current approaches to determine the sole contribution of water soluble carbohydrate (WSC) to animal performance is limited by the fact that chemical components (e.g. nitrogen (N) and WSC) in feed are not independent, at least in pasture. Therefore, this study was designed to test the effect of increasing dietary WSC concentration, at a consistently high N concentration, on N utilisation and isotopic fractionation. Results showed inclusion of WSC neither improved microbial protein synthesis nor N utilisation. Further, the study failed to confirm the use of N isotopic fractionation as a simple indicator of N partitioning.

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“…Unfortunately, the number of data obtained with this method is fairly limited compared with growth-based predictions. Moreover, N balance studies can also lead to biases of overestimation of N retention (Spanghero and Kowalski, 1997 (Sengar, 1980;Akinsoyinu, 1985). For temperate goat genotypes, DCP maintenance requirements have been estimated at 2.82 g and 2.13 g/kg LW 0.75 by the NRC (1981) and the INRA (1989), respectively.…”

Section: Lw Gain Requirementsmentioning

confidence: 99%

Nutritional requirements of sheep, goats and cattle in warm climates: a meta-analysis

Salah

Sauvant

Archimède

2014

Animal

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The objective of the study was to update energy and protein requirements of growing sheep, goats and cattle in warm areas through a meta-analysis study of 590 publications. Requirements were expressed on metabolic live weight (MLW = LW 0.75 ) and LW 1 basis. The maintenance requirements for energy were 542.64 and 631.26 kJ ME/kg LW 0.75 for small ruminants and cattle, respectively, and the difference was significant ( P < 0.01). The corresponding requirement for 1 g gain was 24.3 kJ ME without any significant effect of species. Relative to LW 0.75 , there was no difference among genotypes intra-species in terms of ME requirement for maintenance and gain. However, small ruminants of warm and tropical climate appeared to have higher ME requirements for maintenance relative to live weight (LW) compared with temperate climate ones and cattle. Maintenance requirements for protein were estimated via two approaches. For these two methods, the data in which retained nitrogen (RN) was used cover the same range of variability of observations. The regression of digestible CP intake (DCPI, g/kg LW 0.75 ) against RN (g/kg LW 0.75 ) indicated that DCP requirements are significantly higher in sheep (3.36 g/kg LW 0.75 ) than in goats (2.38 g/kg LW 0.75 ), with cattle intermediate (2.81 g/kg LW 0.75 ), without any significant difference in the quantity of DCPI/g retained CP (RCP) (40.43). Regressing metabolisable protein (MP) or minimal digestible protein in the intestine (PDI min ) against RCP showed that there was no difference between species and genotypes, neither for the intercept (maintenance = 3.51 g/kg LW 0.75 for sheep and goat v. 4.35 for cattle) nor for the slope (growth = 0.60 g MP/g RCP). The regression of DCP against ADG showed that DCP requirements did not differ among species or genotypes. These new feeding standards are derived from a wider range of nutritional conditions compared with existing feeding standards as they are based on a larger database. The standards seem to be more appropriate for ruminants in warm and tropical climates around the world.

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Critical analysis of N balance experiments with lactating cows

Cited by 119 publications

References 44 publications

Low degradable protein supply to increase nitrogen efficiency in lactating dairy cows and reduce environmental impacts at barn level

Low degradable protein supply to increase nitrogen efficiency in lactating dairy cows and reduce environmental impacts at barn level

The effect of dietary water soluble carbohydrate to nitrogen ratio on nitrogen partitioning and isotopic fractionation of lactating goats offered a high-nitrogen diet

Nutritional requirements of sheep, goats and cattle in warm climates: a meta-analysis

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