ABSTRACT The objective of this study was to validate near-infrared reflectance spectroscopy (NIRS... more ABSTRACT The objective of this study was to validate near-infrared reflectance spectroscopy (NIRS) applied to faeces (FNIRS) for estimating the grass in vivo organic matter digestibility (G-OMD) and the grass dry matter intake (G-DMI, kg/d) of concentrate-supplemented grazing dairy cows. The G-OMD estimates from one FNIRS model were compared with two estimates using faecal nitrogen indicator (FNI) methods. Similarly, two FNIRS models were compared with the ratio technique (RT) and with three animal performance methods (APM) for estimating G-DMI. The results were analysed at cow and herd level in two grazed paddocks (P1 and P2) in a rotational grazing scheme. For both G-OMD and G-DMI, the DIMS estimations were correlated (P < 0.05) with other predictive methods (r = 0.61 for G-OMD and r = 0.63-0.88 for G-DMI). Depending on the estimation method, the G-OMD varied from 0.689 (FNIRS) to 0.773 (FNI). The FNI estimates were generally higher and were similar to the G-OMD estimates obtained from NIRS analyses of grass sampled in the field. The FNIRS and FNI estimates were biased at cow and paddock level by 0.01-0.1 digestibility units (P < 0.001). Depending on the estimation method, the G-DMI estimates varied from 11.9 to 16.4 kg/d. FNIRS and APM produced similar estimates of G-DMI at both cow and herd level. The RT estimates of G-DMI were 3 kg/d higher than the FNIRS and APM estimates (P < 0.05). The G-DMI estimated by RT methods was particularly high for P2, with a mean value of 18.5 kg/d, which seemed too high in terms of the maximum intake capacity of supplemented grazing dairy cows. For both G-OMD and G-DMI and for all the estimation methods, inter-cow and intra-paddock variations, expressed through the coefficient of variation (SD/mean), ranged from 0.05 to 0.40. As the accuracy of the FNIRS models, expressed through the standard error of cross validation (SECV), was lower than these inter-animal and intra-paddock variations, we suggest that FNIRS could be used to record, quickly and easily, the evolution of grass digestibility and the intake of grazing dairy cows. These estimates could be implemented through decision-support systems aimed at improving the management of grazing dairy herds.
In ruminants near infrared spectroscopy of faeces (F.NIRS) can measure the concentrations of faec... more In ruminants near infrared spectroscopy of faeces (F.NIRS) can measure the concentrations of faecal constituents such as N and fibre. It can also directly estimate many diet attributes, including total N, fibre, digestibility and the major plant groups (e.g. monocots versus dicots, and some plant species). In some situations F.NIRS can be used to estimate voluntary intake and liveweight change, but it is difficult to encompass animal effects (e.g. lactation, maturity), pasture availability or mineral deficiencies. Application of F.NIRS, especially in conjunction with other measurements (e.g. metabolizable energy intake calculated from liveweight change, 13C/12C ratio in faeces, microbial protein synthesis and phosphorus concentrations in faeces) can provide valuable and reliable information about the nutritional status of grazing ruminants. Examples where F.NIRS has been used to measure the nutritional status of grazing cattle and sheep are described for extensive and intensive trop...
Le pâturage mixte de petits et gros ruminants constitue une conduite agro ecologique pour amelior... more Le pâturage mixte de petits et gros ruminants constitue une conduite agro ecologique pour ameliorer les croissances individuelles et a l'hectare, en valorisant les complementarites alimentaires des especes animales, tout en reduisant l’impact du parasitisme gastro-intestinal pour les petits ruminants. Pour des ovins, une meta-analyse de la litterature a mis en evidence un gain de poids individuel de + 15 g /animal/jour, variable en fonction du stade physiologique considere (allaitement, pre ou post-sevrage) et un gain a l’hectare de + 29 % en pâturage mixte, compare a du pâturage d’ovins seuls. Pour des caprins, une experimentation de deux ans en milieu tropical a revele un gain individuel de + 14 g de poids vif/animal/jour en mixte, et un gain global a l’hectare double, voire plus, si l’on considere la biomasse presente, mieux exploitee en pâturage mixte. Pour les bovins conduits en mixte, le gain est moins net, fluctue entre les etudes, mais est a minima equivalent a celui enr...
Le développement de la population de chèvres allaitantes et laitières accompagne l’accroissement ... more Le développement de la population de chèvres allaitantes et laitières accompagne l’accroissement de la population humaine dans les zones tropicale et intertropicale. Du fait de leur grande adaptabilité, les caprins y sont élevés dans une gamme étendue de conditions agro-environnementales et selon un large éventail de systèmes de production, souvent traditionnels et peu artificialisés. Les potentialités des animaux et la multifonctionnalité des systèmes sont mises en avant dans de nombreux travaux scientifiques. Cette synthèse fait un état des lieux de l’élevage caprin en zone tropicale et suggère des pistes d’amélioration des performances zootechniques selon les systèmes d’élevage considérés. Les propositions sont formulées dans une perspective de développement durable, avec un apport maîtrisé en intrants. Ainsi, l'utilisation de «l'effet mâle» permet d'induire l'oestrus et l'ovulation et d'augmenter la fertilité globale du troupeau, la reproduction étant un ...
Mixed grazing systems combining sheep and cattle have shown better growth performance for one or ... more Mixed grazing systems combining sheep and cattle have shown better growth performance for one or both species. This observation has been attributed to their complementary feeding behaviour and the reduced host infection by gastrointestinal nematodes. Less attention has been paid to mixed grazing systems combining goats and cattle. Here, continuously grazing goats mixed with cattle (M) were compared with control goats reared alone (C) under tropical conditions. The comparison was conducted with gastrointestinal nematode-infected (I) and non-infected (nI) goats. Thus, the four treatments were cattle with gastrointestinal nematode-infected goats (MI), gastrointestinal nematode-infected goats alone (CI), cattle with non-infected goats (MnI) and non-infected goats (CnI). Average daily gain (ADG, g/day) and grass production were measured for the four groups of animals (six goats and two heifers treated with MI or MnI) grazing for 3 months on 4 subplots. Monthly measurements were performed...
It is essential to quantify the potential of tropical grasslands to allow significant feed effici... more It is essential to quantify the potential of tropical grasslands to allow significant feed efficiency for grazing livestock in controlled conditions such as at pasture. We conducted a quantitative analysis of published studies reporting the experimental results of average daily gains (ADG) and diet characteristics obtained specifically under grazing conditions (17 publications and 41 experiments), which have been less studied compared with controlled conditions in stalls. The database was analyzed to determine the average and range of values obtained for ADG (g/kg BW), dry matter digestibility, intake (DMI) and digestible DMI (DDMI, g/kg BW) and feed conversion efficiencies (FCE), as well as to predict the response of these parameters to the main strategies investigated in the literature – that is, mainly the stocking rate (SR) and the concentrate intake (CI). The ADG reached 1.2 kg BW per day and was directly linked to DDMI (ADG=−1.63+0.42 DDMI −0.0084 DDMI2,n=90, r.m.s.e=0.584,R2=...
SUMMARYMixed grazing is an alternative pasture management which can be used to increase ruminant ... more SUMMARYMixed grazing is an alternative pasture management which can be used to increase ruminant performance and reduce gastro-intestinal nematodes. A meta-analysis was performed on the results of previous studies from the literature to quantify the benefit of mixed grazing with sheep and cattle and identify determinants and enhancing factors. The analysis focused on papers reporting measurements of average daily weight gain (ADG) of sheep and cattle, carried out simultaneously in mixed grazing and in mono-grazing. The meta-analysis used 179 observations from 16 experiments published in nine carefully selected papers. The benefits of mixed grazing were appraised using the individual ADG of sheep (ADGisheep), cattle (ADGicattle) and the overall performances (ADG per hectare (ADGha), g/day/ha). A theoretical production value (ADGha-Theo) was calculated from the ADGha in mixed and mono-grazing at similar stocking rates (SRs)/ha. The ADGisheepwas greater in mixed treatments compared wit...
So far, little has been done on the effect of nitrogen fertilizer on intake and digestibility in ... more So far, little has been done on the effect of nitrogen fertilizer on intake and digestibility in tropical grazing conditions. The effect of two nitrogen levels, 0 (NF) and 50 kg/ha (F) for three successive grazing cycles, on organic matter intake (OMi) and digestibility (OMd) for Creole heifers (208 kg live weight) was determined. Two groups of four tethered heifers, allowed 18 kg of dry matter daily, grazed individual NF or F circular areas at 28 re-growth days. The heifers were moved and watered daily. Sward characteristics (height, herbage mass, morphological and chemical composition and in situ tiller measurements), OMi, OMd and feeding behaviour (biting rate, bite size, intake rate, grazing and ruminating times) were evaluated simultaneously per circular area.Under nitrogen fertilizer, the stems elongated rapidly (by 133%) as did the leaves, but to a lesser extent (by 40%). Consequently, canopy height, leaf and stem masses and crude protein content increased (respectively by 10...
Faecal indices were evaluated to assess organic matter digestibility (OMD) for small ruminants fe... more Faecal indices were evaluated to assess organic matter digestibility (OMD) for small ruminants fed with Digitaria decumbens. A continuous digestibility trial was conducted with five Creole bucks and five Black-belly rams, fed with fresh cut Digitaria decumbens from 15 to 70 days of re-growth. The amount of herbage offered, the refusals and the faeces were weighed daily for each animal during 55 days. Herbage and faeces samples were kept to determine dry and organic matter (DM and OM), crude protein (CP), neutral and acid detergent fibre (NDF and ADF) and lignin contents (ADL). OMD was calculated per week and per animal. Predictive regressions of OMD were calculated for each species, from all the faecal components measured (CPf, NDFf, ADFf and ADLf), using linear or curvilinear models. Regressions from CPf had the lowest residual standard error (<0·028) when calculated for each species, compared with regressions from the other faecal components. Among the regressions from CPf, the...
ABSTRACT The objective of this study was to validate near-infrared reflectance spectroscopy (NIRS... more ABSTRACT The objective of this study was to validate near-infrared reflectance spectroscopy (NIRS) applied to faeces (FNIRS) for estimating the grass in vivo organic matter digestibility (G-OMD) and the grass dry matter intake (G-DMI, kg/d) of concentrate-supplemented grazing dairy cows. The G-OMD estimates from one FNIRS model were compared with two estimates using faecal nitrogen indicator (FNI) methods. Similarly, two FNIRS models were compared with the ratio technique (RT) and with three animal performance methods (APM) for estimating G-DMI. The results were analysed at cow and herd level in two grazed paddocks (P1 and P2) in a rotational grazing scheme. For both G-OMD and G-DMI, the DIMS estimations were correlated (P &lt; 0.05) with other predictive methods (r = 0.61 for G-OMD and r = 0.63-0.88 for G-DMI). Depending on the estimation method, the G-OMD varied from 0.689 (FNIRS) to 0.773 (FNI). The FNI estimates were generally higher and were similar to the G-OMD estimates obtained from NIRS analyses of grass sampled in the field. The FNIRS and FNI estimates were biased at cow and paddock level by 0.01-0.1 digestibility units (P &lt; 0.001). Depending on the estimation method, the G-DMI estimates varied from 11.9 to 16.4 kg/d. FNIRS and APM produced similar estimates of G-DMI at both cow and herd level. The RT estimates of G-DMI were 3 kg/d higher than the FNIRS and APM estimates (P &lt; 0.05). The G-DMI estimated by RT methods was particularly high for P2, with a mean value of 18.5 kg/d, which seemed too high in terms of the maximum intake capacity of supplemented grazing dairy cows. For both G-OMD and G-DMI and for all the estimation methods, inter-cow and intra-paddock variations, expressed through the coefficient of variation (SD/mean), ranged from 0.05 to 0.40. As the accuracy of the FNIRS models, expressed through the standard error of cross validation (SECV), was lower than these inter-animal and intra-paddock variations, we suggest that FNIRS could be used to record, quickly and easily, the evolution of grass digestibility and the intake of grazing dairy cows. These estimates could be implemented through decision-support systems aimed at improving the management of grazing dairy herds.
In ruminants near infrared spectroscopy of faeces (F.NIRS) can measure the concentrations of faec... more In ruminants near infrared spectroscopy of faeces (F.NIRS) can measure the concentrations of faecal constituents such as N and fibre. It can also directly estimate many diet attributes, including total N, fibre, digestibility and the major plant groups (e.g. monocots versus dicots, and some plant species). In some situations F.NIRS can be used to estimate voluntary intake and liveweight change, but it is difficult to encompass animal effects (e.g. lactation, maturity), pasture availability or mineral deficiencies. Application of F.NIRS, especially in conjunction with other measurements (e.g. metabolizable energy intake calculated from liveweight change, 13C/12C ratio in faeces, microbial protein synthesis and phosphorus concentrations in faeces) can provide valuable and reliable information about the nutritional status of grazing ruminants. Examples where F.NIRS has been used to measure the nutritional status of grazing cattle and sheep are described for extensive and intensive trop...
Le pâturage mixte de petits et gros ruminants constitue une conduite agro ecologique pour amelior... more Le pâturage mixte de petits et gros ruminants constitue une conduite agro ecologique pour ameliorer les croissances individuelles et a l'hectare, en valorisant les complementarites alimentaires des especes animales, tout en reduisant l’impact du parasitisme gastro-intestinal pour les petits ruminants. Pour des ovins, une meta-analyse de la litterature a mis en evidence un gain de poids individuel de + 15 g /animal/jour, variable en fonction du stade physiologique considere (allaitement, pre ou post-sevrage) et un gain a l’hectare de + 29 % en pâturage mixte, compare a du pâturage d’ovins seuls. Pour des caprins, une experimentation de deux ans en milieu tropical a revele un gain individuel de + 14 g de poids vif/animal/jour en mixte, et un gain global a l’hectare double, voire plus, si l’on considere la biomasse presente, mieux exploitee en pâturage mixte. Pour les bovins conduits en mixte, le gain est moins net, fluctue entre les etudes, mais est a minima equivalent a celui enr...
Le développement de la population de chèvres allaitantes et laitières accompagne l’accroissement ... more Le développement de la population de chèvres allaitantes et laitières accompagne l’accroissement de la population humaine dans les zones tropicale et intertropicale. Du fait de leur grande adaptabilité, les caprins y sont élevés dans une gamme étendue de conditions agro-environnementales et selon un large éventail de systèmes de production, souvent traditionnels et peu artificialisés. Les potentialités des animaux et la multifonctionnalité des systèmes sont mises en avant dans de nombreux travaux scientifiques. Cette synthèse fait un état des lieux de l’élevage caprin en zone tropicale et suggère des pistes d’amélioration des performances zootechniques selon les systèmes d’élevage considérés. Les propositions sont formulées dans une perspective de développement durable, avec un apport maîtrisé en intrants. Ainsi, l'utilisation de «l'effet mâle» permet d'induire l'oestrus et l'ovulation et d'augmenter la fertilité globale du troupeau, la reproduction étant un ...
Mixed grazing systems combining sheep and cattle have shown better growth performance for one or ... more Mixed grazing systems combining sheep and cattle have shown better growth performance for one or both species. This observation has been attributed to their complementary feeding behaviour and the reduced host infection by gastrointestinal nematodes. Less attention has been paid to mixed grazing systems combining goats and cattle. Here, continuously grazing goats mixed with cattle (M) were compared with control goats reared alone (C) under tropical conditions. The comparison was conducted with gastrointestinal nematode-infected (I) and non-infected (nI) goats. Thus, the four treatments were cattle with gastrointestinal nematode-infected goats (MI), gastrointestinal nematode-infected goats alone (CI), cattle with non-infected goats (MnI) and non-infected goats (CnI). Average daily gain (ADG, g/day) and grass production were measured for the four groups of animals (six goats and two heifers treated with MI or MnI) grazing for 3 months on 4 subplots. Monthly measurements were performed...
It is essential to quantify the potential of tropical grasslands to allow significant feed effici... more It is essential to quantify the potential of tropical grasslands to allow significant feed efficiency for grazing livestock in controlled conditions such as at pasture. We conducted a quantitative analysis of published studies reporting the experimental results of average daily gains (ADG) and diet characteristics obtained specifically under grazing conditions (17 publications and 41 experiments), which have been less studied compared with controlled conditions in stalls. The database was analyzed to determine the average and range of values obtained for ADG (g/kg BW), dry matter digestibility, intake (DMI) and digestible DMI (DDMI, g/kg BW) and feed conversion efficiencies (FCE), as well as to predict the response of these parameters to the main strategies investigated in the literature – that is, mainly the stocking rate (SR) and the concentrate intake (CI). The ADG reached 1.2 kg BW per day and was directly linked to DDMI (ADG=−1.63+0.42 DDMI −0.0084 DDMI2,n=90, r.m.s.e=0.584,R2=...
SUMMARYMixed grazing is an alternative pasture management which can be used to increase ruminant ... more SUMMARYMixed grazing is an alternative pasture management which can be used to increase ruminant performance and reduce gastro-intestinal nematodes. A meta-analysis was performed on the results of previous studies from the literature to quantify the benefit of mixed grazing with sheep and cattle and identify determinants and enhancing factors. The analysis focused on papers reporting measurements of average daily weight gain (ADG) of sheep and cattle, carried out simultaneously in mixed grazing and in mono-grazing. The meta-analysis used 179 observations from 16 experiments published in nine carefully selected papers. The benefits of mixed grazing were appraised using the individual ADG of sheep (ADGisheep), cattle (ADGicattle) and the overall performances (ADG per hectare (ADGha), g/day/ha). A theoretical production value (ADGha-Theo) was calculated from the ADGha in mixed and mono-grazing at similar stocking rates (SRs)/ha. The ADGisheepwas greater in mixed treatments compared wit...
So far, little has been done on the effect of nitrogen fertilizer on intake and digestibility in ... more So far, little has been done on the effect of nitrogen fertilizer on intake and digestibility in tropical grazing conditions. The effect of two nitrogen levels, 0 (NF) and 50 kg/ha (F) for three successive grazing cycles, on organic matter intake (OMi) and digestibility (OMd) for Creole heifers (208 kg live weight) was determined. Two groups of four tethered heifers, allowed 18 kg of dry matter daily, grazed individual NF or F circular areas at 28 re-growth days. The heifers were moved and watered daily. Sward characteristics (height, herbage mass, morphological and chemical composition and in situ tiller measurements), OMi, OMd and feeding behaviour (biting rate, bite size, intake rate, grazing and ruminating times) were evaluated simultaneously per circular area.Under nitrogen fertilizer, the stems elongated rapidly (by 133%) as did the leaves, but to a lesser extent (by 40%). Consequently, canopy height, leaf and stem masses and crude protein content increased (respectively by 10...
Faecal indices were evaluated to assess organic matter digestibility (OMD) for small ruminants fe... more Faecal indices were evaluated to assess organic matter digestibility (OMD) for small ruminants fed with Digitaria decumbens. A continuous digestibility trial was conducted with five Creole bucks and five Black-belly rams, fed with fresh cut Digitaria decumbens from 15 to 70 days of re-growth. The amount of herbage offered, the refusals and the faeces were weighed daily for each animal during 55 days. Herbage and faeces samples were kept to determine dry and organic matter (DM and OM), crude protein (CP), neutral and acid detergent fibre (NDF and ADF) and lignin contents (ADL). OMD was calculated per week and per animal. Predictive regressions of OMD were calculated for each species, from all the faecal components measured (CPf, NDFf, ADFf and ADLf), using linear or curvilinear models. Regressions from CPf had the lowest residual standard error (<0·028) when calculated for each species, compared with regressions from the other faecal components. Among the regressions from CPf, the...
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