Suitability of electronic mini-boluses for early identification of lambs

Three types of ceramic mini-boluses, B1 [13.8 g; 10.5 x 51.0 mm (o.d. x length)], B2 (16.2 g; 12.2 x 42.2 mm), and B3 (20.1 g; 11.2 x 56.4 mm), were used to electronically identify as soon as possible after birth a total of 545 lambs of 3 breeds: Ripollesa (meat breed, n = 274), Manchega (dairy breed, n = 129), and Lacaune (dairy breed, n = 142). Boluses were administered by a trained operator using a balling gun or directly by hand. Lambs were also identified with 2 types of plastic ear tags in the left (temporary, 1.5 g) and the right (permanent, 4.1 g) ears. Lamb and identification device performances were checked during suckling (to wk 5 or 7) and fattening. At 24 kg of BW, lambs were slaughtered (n = 385) or kept for breeding (n = 144). No differences in performance were observed between the 2 dairy breeds, and their data were pooled. Minimum BW for bolus administration was lower in dairy than in meat lambs (P < 0.001). Across breeds, B1 and B3 did not differ in lamb age (27 d) and weight (9.2 kg) at administration, but B2 required older and heavier lambs (33 d and 11.1 kg; P < 0.01). Boluses did not affect lamb performance, but final readability at slaughter differed between B1 and B2 (97.7 and 95.2%, respectively) and B3 (100%), and between ear tags (temporary, 98.1; permanent, 100%). Bolus recovery was 100% in all cases, but the proportion of boluses found in the reticulum varied among bolus type (83.3 to 93.8%; P < 0.05). Three B1 (2%) were recovered from the abomasum. In a second experiment, effects of the intermediate mini-bolus (B2) on diet digestibility were evaluated. Digestibility of control and bolus-administered, Manchega ram lambs (14.9 kg of BW; n = 8) fed ad libitum with 2 pelleted concentrates and barley straw was assessed in digestibility crates. Feed intake and nutrient digestibility were measured in four 21-d periods, during which lambs received the 2 diets consecutively. No differences in intake, growth performance, or nutrient digestibility were observed between control and bolused lambs. In conclusion, the B3 mini-bolus proved to be an efficient device for identification of lambs before weaning (recommended age, >4 wk; recommended BW, >10 kg), allowing a reliable traceability of dairy and meat lambs until slaughter.     

Effects of underfeeding and refeeding on weight and cellularity of splanchnic organs in ewes.

We assessed the effects of a long and severe period of underfeeding, followed by a rapid refeeding with a high-concentrate diet, on weight, protein mass, and cellularity of the splanchnic organs in adult ewes. Twenty-four ewes, allocated to four groups of six, were fed a forage diet (50% regrowth of natural grassland hay and 50% wheat straw) either at maintenance (groups M and MO) or at 40% maintenance (groups U and UO) for 78 d. Groups M and U were then slaughtered, and groups MO and UO were subsequently overfed a high-concentrate diet (52% hay, 20% barley, 16% rapeseed meal, 4% fish meal, and 8% Megalac) at 236% maintenance for 26 d before being slaughtered. During the experiment, feed was adjusted to maintain feed supply at a constant percentage of animal requirements. After slaughter, fresh weight, dry weight, and protein mass of the reticulorumen, omasum, abomasum, small intestine, large intestine, and liver were measured. Cellularity was assessed from nucleic acids and protein contents for both ruminal mucosa and muscular-serosa layers, jejunum, and liver. The concentrations of ubiquitin and cathepsin D mRNA were measured in ruminal mucosa and muscular-serosa layers and in jejunum. Underfeeding decreased protein mass of splanchnic organs, especially in liver (-29%) and reticulorumen (-39%). Refeeding previously underfed animals increased protein mass of liver (+102%) and small intestine (+59%). No carry-over effect of the previous level of intake (UO vs. MO) was observed on the protein mass of splanchnic tissues after 26 d of refeeding. Variations in liver mass were mainly due to hypertrophy, as determined by the protein:DNA ratio, whereas variations in small intestinal mass were mainly due to hyperplasia, as determined by the amount of DNA. By contrast, changes in rumen mass associated with increasing ME intake seemed to be related to hypertrophy in the muscular-serosal component and hyperplasia in the epithelial component. The concentrations of ubiquitin and cathepsin D mRNA in the rumen and jejunum were not modified by feeding level, demonstrating that the expression of these genes for proteolytic enzymes was unchanged under these conditions.     

Leptin in ruminants. Gene expression in adipose tissue and mammary gland, and regulation of plasma concentration

This paper reviews data on leptin gene expression in adipose tissue (AT) and mammary gland of adult ruminants, as well as on plasma leptin variations, according to genetic, physiological, nutritional and environmental factors. AT leptin mRNA level was higher in sheep and goat subcutaneous than visceral tissues, and the opposite was observed in cattle; it was higher in fat than in lean selection line in sheep; it was decreased by undernutrition and increased by refeeding in cattle and sheep, and not changed by adding soybeans to the diet of lactating goats; it was increased by injection of NPY to sheep, and by GH treatment of growing sheep and cattle. Insulin and glucocorticoids in vitro increased AT leptin mRNA in cattle, and leptin production in sheep. Long daylength increased AT lipogenic activities and leptin mRNA, as well as plasma leptin in sheep. Mammary tissue leptin mRNA level was high during early pregnancy and was lower but still expressed during late pregnancy and lactation in sheep. Leptin was present in sheep mammary adipocytes, epithelial and myoepithelial cells during early pregnancy, late pregnancy and lactation, respectively. Plasma leptin in cattle and sheep was first studied thanks to a commercial “multi-species” kit. It was positively related to body fatness and energy balance or feeding level, and decreased by β-agonist injection. The recent development of specific RIA for ruminant leptin enabled more quantitative study of changes in plasma leptin concentration, which were explained for 35–50% by body fatness and for 15–20% by feeding level. The response of plasma leptin to meal intake was related positively to glycemia, and negatively to plasma 3-hydroxybutyrate. The putative physiological roles of changes in leptin gene expression are discussed in relation with published data on leptin receptors in several body tissues, and on in vivo or in vitro effects of leptin treatment.     

Effects of small ruminal boluses used for electronic identification of lambs on the growth and development of the reticulorumen

Fifty-four male lambs were used to study the effects of two types of small electronic boluses on the dimensions and epithelial characteristics of their reticulorumen. Newborn lambs were assigned according to bolus type and age of application to the following treatments: 1) control (C, n = 21), without bolus; 2) mini (M, n = 21), identified with a 9.3 x 37.4-mm, 5.2-g bolus during the first week after birth; and 3) small (S, n = 12), identified with a 15.0 x 39.1-mm, 20-g bolus after weaning at wk 5, when lambs weighed more than 12 kg. After weaning, lambs were given ad libitum access to concentrate and barley straw. Six lambs were euthanized at the start of the experiment to measure initial reticulorumen characteristics. Ten lambs (five from M and five from C treatments) were slaughtered at weaning and 24 (eight per treatment) were slaughtered when they reached 24 kg. After bolus recovery, the reticulorumen was emptied and filled with polyurethane foam to obtain reticulorumen casts. Weight of the emptied reticulorumen and volume of the casts were measured. Four representative lambs from each treatment were also slaughtered at 24 kg, and their reticulorumen used to evaluate papillae size, number of dead cells, and degree of keratinization of both the reticulum wall and the rumen wall epithelia. Weight at weaning (13.8 kg), age at the end of fattening (65 d), and mortality rate (4%) did not differ among treatments. Retention rate for M and S boluses was 82.4 and 100%, respectively. Fresh weight and volume of the reticulorumen did not differ among treatments at weaning (130 g and 1,679 mL) or at the end of the fattening period (640 g and 5,931 mL). Lambs in the M treatment had greater (P < 0.05) rumen papillae size and lower (P < 0.10) keratinization than C lambs; values in the S lambs were intermediate between M and C lambs. Neither the M nor S type of bolus affected dimensions of the reticulorumen, but the earlier presence of M boluses induced a greater papillae size, with no negative effects on health and fattening performances of young lambs.     

Contextualized re-calculation of enteric methane emission factors for small ruminants in sub-humid Western Africa is far lower than previous estimates

Tropical Animal Health and Production - Given the projected growth of methane emission by ruminants in developing countries, there is a clear need for reliable estimates of their contribution to...     

GAMEDE: A global activity model for evaluating the sustainability of dairy enterprises. Part II – Interactive simulation of various management strategies with diverse stakeholders

GAMEDE is a stock-flow dynamic simulation model designed with farmers to represent dairy farm functioning and the consequences of the farmer’s daily management decisions for whole-farm sustainability. Sustainability is evaluated according to its three pillars: technico-economic viability, respect for environment, and social liveability. The model provides original information for a better understanding of the processes regulating nitrogen dynamics within the farm, and the factors determining farmers’ decisions and practices. Model implementation experiments have revealed that GAMEDE is also a useful tool to support discussions and to generate knowledge exchange among various stakeholders who play an important role in the development of farm sustainability: farmers, extension agents and researchers.While a majority of researchers and advisers are specialised and a majority of farmers fix their attention on specific and narrow themes of farm management, such a comprehensive model can help stakeholders complement their knowledge to gain a holistic view of the farming system. This holistic and integrated view is crucial: (i) for researchers who wish to explain diversity in farming systems and understand decisional and biophysical processes and their interrelated effects operating in such complex agro-ecosystems, (ii) for advisers whose aim is to define alternative management strategies applicable in practice, i.e. taking into account farm specificities, and (iii) for farmers who must choose practices compatible with their resources, assets, constraints and objectives.Holism can also improve versatility and thus the generic character of models. Issues are narrowly specified and greatly vary both among categories of stakeholders (e.g. scientists versus farmers) and within each category (e.g. among farmers). A comprehensive model that: (i) details all farm management operations, and (ii) represents their effects on different spatio-temporal levels and on the three sustainability dimensions, is more likely to respond to the various issues facing different stakeholders. We argue that capacity of models to respond to stakeholders’ questions has to be considered in future evaluations of decision support systems.     

Formation of clay from granite and its distribution in relation to climate and topography

Chemical weathering can be approached from three interpretive points of view: distribution of the secondary minerals in landscapes, weathering of primary minerals and geochemistry of ions in solution. On granitic rocks it is posible to define both climatic and topographic sequences of distribution of clays in association with weathering products: gibbsite - kaolinite - hydrous iron oxides - hydrous manganese oxides - iron-rich montmorillonite - calcium carbonate - calcium sulfate - sodium carbonates and silicates. These stages appear as an absolute accumulation formed by filling of intergranular pores. Another sequence can be found not in intergranular pores but in the cracks and along the cleavages of primary minerals from which they are derived by relative accumulation. The order of appearance of these secondary minerals remains the same regardless of the nature of climates and the topographic position. The conditions of equilibrium are not identical in the interior of grains of different primary minerals nor in the pores outside of them and the secondary minerals found in the different situations are also not identical. This is well demonstrated by the chemistry of waters draining slopes. The equilibrium diagrams and balances between cations and silica sometimes result in disagreement, proving that equilibrium conditions are not satisfied between solutions circulating in the pores and clay minerals found inside the primary minerals.     

Plasma leptin concentration in adult cattle: effects of breed,adiposity, feeding level,and meal intake

An ovine-specific RIA, shown to be reliable for bovine leptin determination, was used to study the effects of breed, body fatness, feeding level, and meal intake on plasma leptin level in adult cattle. Eighteen fat Charolais, fat Holstein, and lean Holstein adult cows were either well-fed (130% of maintenance energy requirements [MER]) or underfed (60% of MER) for 3 wk. The breed tended to have a small effect on plasma leptin level, which was decreased by 70% (P < 0.05) in lean compared to fat Holstein cows. A strong curvilinear relationship was found between mean adipocyte volume and plasma leptin concentrations in well-fed (r = +0.95) and underfed (r = +0.91) cows. Underfeeding caused a significant decrease in plasma leptin levels from 8.0+/-3.1 to 6.1+/-2.3 ng/mL (P < 0.01). Nine adult Holstein cows initially fed at 130% of MER (control) were underfed to 21% of MER for 7 d, and five of them were refed to 237% of MER for 21 d. Plasma leptin measured 1 h before meal distribution was decreased from 5.9+/-0.4 to 3.8+/-0.2 ng/mL (P < 0.01) by underfeeding and increased to reach 8.8+/-1.0 ng/mL (P < 0.01) after refeeding. It was positively related to plasma glucose (r = +0.52, P < 0.01) and negatively related to plasma NEFA (r = -0.67, P < 0.001). Plasma leptin measured 4 h after meal distribution was positively related to feeding level and to plasma 3-OH-butyrate (r = +0.61, P < 0.005) and negatively related to plasma NEFA (r = -0.56, P < 0.01). Differences between pre- and postprandial leptin concentrations showed a decrease after meal intake in control and well-fed cows (-7 and -19%, P < 0.01, respectively) and an increase in underfed cows (+12%, P < 0.01). Leptin response to meal intake was positively related to glucose response (r = +0.66, P < 0.001) and negatively related to 3-OH-butyrate response (r = -0.78, P < 0.001). By using the "multispecies" commercial RIA, leptin concentrations were lower and we observed similar physiological responses, although less related to other hormones or metabolites. These data provide evidence, first, that a specific RIA for ruminant leptin determination is necessary to better understand leptin regulation, and second, that plasma leptin is strongly related to adipose cell size and positively related to feeding level in adult cattle, and that an effect of meal intake could be mediated by glucose and(or) ketone bodies.