Rumen function in goats, an example of adaptive capacity.

The aim of this Research Reflection is to describe the basic rumen function of goats and its modification in response to environmental factors, as well as to discuss similarities and differences when compared to other ruminants. In so doing we shall reveal the adaptive capacity of goats to harsh environments. The basic rumen function in goats is similar to other species of ruminants, as stressed by the opportunity to apply the updates of feeding systems for ruminants to goats. The rumen epithelium acts as a protective barrier between the rumen and the host, but it can be damaged by toxic compounds or acidosis. The rumen also plays an important role in water balance, both for dehydration and rehydration. Recent studies show that the microbiota exhibits a high fractional stability due to functional redundancy and resilience, but this needs more investigation. The microbial community structure differs between goats and cows, which explains the difference in sensitivity to milk fat depression following intake of high lipid diets. Goats also differ from other ruminants by their enhanced ability to feed-sort, but as with cows they can suffer from acidosis. Nevertheless, goats can be considered to be very resistant to environmental factors such as water stress, salt stress or heat stress, and this is especially so in some endogenous breeds. They also are able to detoxify tannins, polyphenols and other secondary metabolites. Some new trials involving feeding behaviour, microbiota and omics or approaches by meta-analyses or modelling will improve our knowledge of rumen function in goats.

End-product quality of composts produced under tropical and temperate climates using different raw materials: A meta-analysis.

A meta-analysis on end-product quality of 442 composts was performed to assess the effects of climate and raw materials on compost quality. The analysis was performed using an ANOVA including a mixed model with nested factors (climate, raw material and publication effect). Tropical composts presented lower carbon, nitrogen, potassium and soluble-carbon contents, and higher electrical conductivity. The results suggest that compost quality in the tropics was affected by weather conditions during composting (e.g. high temperature and rainfall), which induced high losses of carbon and nutrients. For most properties, industrial, sewage sludge and manure-based composts displayed the highest quality under both climates, while the contrary was found for household and municipal solid waste-based composts. The publication effect represented >50% of total variance, which was mainly due to the heterogeneity of the composting procedures. The meta-analysis was found to be a helpful tool to analyse the imbalanced worldwide database on compost quality.

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates.

BACKGROUND: In vitro techniques are used to predict ruminant feedstuff values or characterise rumen fermentation. As the results are influenced by several factors, such as the relative effects of inocula and substrates, this study aimed to examine in vitro incubation of two total mixed rations (substrates) differing in their proportion of concentrate [low (L): 350 g kg(-1) vs. high (H): 700 g kg(-1)] incubated in inocula provided by goats fed either a L or a H diet. Gas production and composition in carbon dioxide (CO2), methane (CH4 ) and hydrogen (H2), volatile fatty acids (VFAs), soluble carbohydrates (SCs) and ammonia (NH3) concentrations, and pH of the fermentation fluid were measured. RESULTS: In comparison with the L inoculum and L substrate, the H ones produced more CO2 and CH4 gas, which led to higher SCs and VFA concentrations, and lower acetate-to-propionate ratio and NH3 concentration, with a predominant effect of the inoculum. CONCLUSION: The effects of the inocula and of the substrates were additive using donor animals adapted to the diets.

Dataset from the literature on the ingestive behaviour of grazing ruminants.

The dataset described in this paper was constructed from 90 publications available from bibliographic databases. It presents the values of various quantitative components of ingestive behaviour of grazing ruminants (bite weight, biting rate, intake rate, grazing time, etc.). These values were coded according to the experimental factors tested and described in the publications, of a temporal nature (season, year, grazing cycle) or linked to the sward management strategies (overall density bulk or of the stems, the stage regrowth or the fertilization) or other pasture management strategies (herbage allowance, pasture access time, stocking rate). Other essential factors were also coded, specifying the characteristics of the grass grazed (height of the grass, apparent density, forage species), the characteristics of the animals used (species, stage, age and body weight) or the measurement methods of behavioural components. This coding process aims to facilitate the identification of subsets of data of interest, and have been analysed for example to highlight the main components determining bite weight or the components linking bite weight to intake rate and daily intake (see reference).

[Control of milk composition and quality on the farm]. / La maîtrise de la composition et de la qualité du lait à la ferme.

Milk and milk products have a reputation for quality among consumers. Yet the raw material--milk collected on the farm--varies widely in its composition and quality depending on the farming conditions, animal genetics, feed, and environmental determinants. The micronutrient content of milk and milk products, their organoleptic qualities, and the factors that influence these characteristics are now better known. Thus, the dairy industry is better able to develop foods meeting modern demands for taste, safety and health-promoting qualities.

Influence of grinding on the nutritive value of peas for ruminants: comparison between in vitro and in situ approaches.

In ruminant nutrition, peas are characterized by high protein solubility and degradability, which impair its protein value estimated by the official in situ method. Grinding can be used as a technological treatment of pea seeds to modify their nutritional value. The aim of this study was to compare the in situ method with an in vitro method on the same pea either in a coarse pea flour form (PCF) or in a ground pea fine flour form (PFF) to understand the effect of grinding. Both forms were also reground (GPCF and GPFF). PCF presented a lower rate of in vitro degradation than PFF, and more stable fermentation parameters (pH, ammonia, soluble carbohydrates) even if gas production was higher for the PCF after 48 h of incubation. In situ dry matter and protein degradation were lower for PCF than those for PFF; these differences were more marked than with the in vitro method. Reground peas were very similar to PFF. The values for pea protein digestible in the intestine (PDI) were higher for PCF than those for PFF. This study points out the high sensitivity of the in situ method to grinding. The study needs to be validated by in vivo measurements.

I. A bibliographic database for quantitative analysis of phosphorus flow in ruminants.

The present study describes a quantitative analysis of phosphorus metabolism in ruminants. The database compiles 100 sources either published (95) or unpublished (5) involving studies on true or apparent phosphorus balances carried out before 1999. The database reports 652 distinct experimental conditions (lines) described with experimental variables (column) involving a total of 2982 animals: 414 lambs (33 references), 1078 sheep (37 references), 64 pregnant ewes (3 references), 212 lactating ewes (5 references), 528 calves (20 references), 4 maintenance cows (1 reference), 519 lactating cows (6 references), 42 kids (1 reference) and 121 lactating goats (3 references). The reliability of the database was tested using some general relationships.

II. Quantitative aspects of phosphorus absorption in ruminants.

Phosphorus absorption in ruminants was analysed from a database described in a previous article. For common values of ingested phosphorus (2.5-5.0 g x kg(-1) of DM), 0.73 of dietary phosphorus is absorbed. The remaining variability is probably due to phosphorus quality. Phosphorus absorbed from silage, cereal, cereal by-products and hay differs greatly. The current true absorption coefficient used to calculate daily phosphorus supply is a constant value in the current systems and often it underestimates the true absorption resulting in an excess of phosphorus being supplied in the diets. Adjusting the true absorption coefficient values requires better characterisation of the phosphorus supplied by each feedstuff. Dietary influences (phytate phosphorus, crude fibre, etc.) were investigated but trials assessing the ration effect on phosphorus absorption are lacking. Since rumen microbes have specific phosphorus requirements, particularly for cell-wall degradation, the feedstuffphosphorus availability for the rumen ecosystem is discussed.

III. Quantitative aspects of phosphorus excretion in ruminants.

Ruminant phosphorus excretion and metabolism were studied through a database. Faecal endogenous phosphorus is the main pathway of phosphorus excretion and averages 0.85 of total faecal phosphorus. The remaining 0.15 is unabsorbed dietary phosphorus. Faecal endogenous phosphorus is mainly unabsorbed phosphorus, with saliva being the major source, and is correlated to factors influencing saliva secretion (DM intake, physical dietary characteristics and dietary phosphorus content). Another source of faecal endogenous phosphorus is rumen microbial phosphorus that escaped solubilisation during post-rumen digestion. All factors stimulating microbial growth would increase phosphorus uptake by the rumen microbes and consequently the faecal endogenous phosphorus. Understanding the determinants of faecal endogenous phosphorus flow will help to precise the determination of net phosphorus requirements for maintenance. The role of plasma phosphorus in urinary phosphorus loss is discussed.