The effect of cultivated mixed-species green fodder on intake,milk production and milk composition of housed dairy goats

The majority of New Zealand dairy goat farmers utilise cultivated green-fed fodder dominated by perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), but evidence from other ruminant species suggests that milk production may be improved when using a more diverse array of species within the green fodder. The aim of this experiment was to determine whether feeding lactating dairy goats a mixed-species green fodder (MF, consisting of perennial ryegrass, timothy (Phleum pratense L.), prairie grass (Bromus willdenowii Kunth), white clover, red clover (Trifolium pratense L.), lucerne (Medicago sativa L.), chicory (Cichorium intybus L.) and plantain (Plantago lanceolata L.) improves dietary intake, milk yield and composition compared with a standard ryegrass and white clover green fodder (SF). Thirty-six mid-lactation goats were housed indoors in pairs and split into two groups (A and B). The trial was split into three periods – firstly a uniformity period of 6 days, in which all goats were fed a combination of both green fodder types, followed by two treatment periods (P1 and P2) of 12 days, respectively. For P1, group A was fed MF and group B was fed SF, and then the group diets were switched for P2. Goats fed MF had 13% greater dry matter intake and 7% greater milk yield than goats fed SF. In addition, the milk protein and fat concentration of goats fed MF were 4% greater than for those fed SF, whereas there was no effect on milk lactose concentration. There was no treatment effect on the levels of protein, glucose, urea or non-esterified fatty acids in the blood of the goats. An effect of green fodder type on milk fat profile was demonstrated, with proportions of pentadecylic acid (C15:0), cis-vaccenic acid (C18:1 c11), linoleic acid (C18:2 n6) and α-linolenic acid (C18:3 n3) being increased in response to MF consumption. In contrast, iso-C15 and iso-C17 proportions were lesser. In summary, this study demonstrated that goats fed MF increased green fodder intake and milk production compared with goats fed SF. The green fodder type affected the fatty acid profile of goat’s milk, with MF increasing the levels of beneficial polyunsaturated omega fatty acids (linoleic and α-linolenic acids).     

Characterization of immune responses against gastrointestinal nematodes in weaned lambs grazing willow fodder blocks

A 131-day rotational grazing experiment was conducted in the summer autumn of 2007/2008 to compare effects of feeding condensed tannin (CT)-containing willow (Salix spp.) fodder blocks (i.e., silvopastoral system) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) control pasture upon the immune response to gastrointestinal nematode parasite infection in Romney weaned lambs. Groups of lambs (n = 40) were allocated to either willow fodder blocks or control pasture; half of each group (n = 20) were regularly-drenched with anthelmintic at approximately 21 day intervals, whilst the remaining 20 weaned lambs were not drenched unless pre-determined faecal nematode egg counts (FEC) were reached, when all weaned lambs in that group were drenched with anthelmintic (i.e., trigger-drenching). Metabolizable energy and CT concentrations were higher in willow fodder versus pasture herbages. Weaned lambs grazing willow fodder blocks had lower live weight gain (92 g/day) and carcass weight (14.4 kg) than those grazing control pasture (134 g; 15.3 kg), with no effect of anthelmintic drenching. Regular anthelmintic treatment maintained similar and low FEC up to day 82, which then increased, whilst trigger-drenched lambs grazing willow fodder blocks had higher FEC than lambs grazing control pasture on three out of eight occasions. As judged by faecal larval cultures, grazing willow fodder blocks reduced the relative proportions of abomasal-dwelling parasites (Haemonchus contortus and Teladorsagia spp.). Trigger-drenched willow fodder block-fed sheep had higher platelet, eosinophil, total white blood cell and lymphocyte counts, greater CD21⁺ and greater γδ (Gamma Delta) TCR⁺ (T cell receptor) lymphocyte subsets than control pasture-fed sheep, and higher plasma levels of Immunoglobulin A (IgA) specific for carbohydrate larval antigen (CarLa) on day 105 (P<0.001). None of these parameters were affected by grazing treatment in regularly-drenched lambs. Higher immunological measurements in trigger-drenched lambs grazing willow fodder blocks could be due to higher larval intake and/or to the effects of secondary compounds in willow fodder blocks priming the immune system. Further research is required to separate these effects.     

Effects of condensed tannin-amended cassava silage blend diets on feeding behavior,digestibility, nitrogen balance,milk yield and milk composition in dairy goats

Condensed tannins (CTs) are phenolic compounds derived from secondary plant metabolism that act as part of the plant's chemical defense system against pathogen invasion and herbivorous attack. This study aimed to evaluate the intake, digestibility, nitrogen (N) balance, production and composition of milk from goats fed cassava silage with added levels of CTs. Eight Anglo-Nubian goats with a mean BW of 40 ± 2.0 kg were distributed in a double Latin square design with four levels of CTs (0, 25, 50 and 75 g/kg DM) with four 20-day periods with 15 days of adaptation and five evaluation days for each period. No differences were observed in DM, NDF, CP intake and feed conversion (grams of DM intake (DMI) per gram of milk produced); however, when expressed as percent of BW, DMI showed a quadratic increase to 29.1 g/kg. As the level of supplemented CTs increased in the diet, the CP digestibility (P = 0.023), NDF (P = 0.044), non-fiber carbohydrates (NFC; P = 0.032) and total digestible nutrients (P = 0.033) exhibited a linear decrease. Furthermore, the addition of CTs to cassava silage induced a linear increase in N-fecal excretion (P = 0.014) and a positive quadratic effect on N-retained (P = 0.014) and N-balance (P = 0.024) as well as a positive quadratic trend in N-digested (P = 0.092). Milk urea N (P = 0.023) decreased linearly. The addition of CTs to cassava silage had a positive quadratic effect on ruminating time (P = 0.011). In addition, comparing the use or non-use from the orthogonal contrast test, the inclusion of CTs in goat diet increased water and N-intake, CP and NDF digestibility, spent time eating and ruminating and N-balance and decreased milk production corrected^3.5%, fat milk content, milk urea N and dry defatted extract of milk. Thus, adding CTs to cassava silage at 25 g/kg total DM promoted goats' greater use of the diet without impairing feed conversion and the quality of goat milk produced. Dietary levels of 50 and 75 g/kg total DM are not recommended because under the conditions of this study, they reduced the productive efficiency of dairy goats.     

Effects of lowering crude protein supply alone or in a combination with essential oils on productivity,rumen function and nutrient utilization in dairy cows

Lowering dietary protein concentration is known to decrease urinary nitrogen (N) losses and increase milk N efficiency in dairy cows, but it may negatively affect animal productivity. Plant-derived essential oils (EO) may alleviate these negative effects by improving the efficiency of rumen fermentation in cows fed reduced feed protein diets. The experiment was conducted to investigate the effects of lowering crude protein (CP) supply alone or in a combination with an EO product on feed intake, milk production and composition, rumen fermentation, total tract digestibility and N utilization in dairy cows. Twenty-one Holstein cows were used in a replicated 3 × 3 Latin square design experiment. Each period consisted of 14 days for adaptation and 14 days for data collection and sampling. Cows were randomly assigned to one of three experimental diets: a 165 g/kg CP diet (control), a 155 g/kg CP diet (LCP) and LCP supplemented with 35 g/day per cow EO (LCPEO). The dry matter (DM) intake was decreased by LCP and LCPEO compared with the control; there was no effect of EO on DM intake. Milk yield and composition and feed efficiency were similar among treatments. Ruminal pH, lactate, ammonia and volatile fatty acids concentrations were not affected by treatment, except increased valerate concentration by LCPEO compared with LCP. The supplementation of EO tended to decrease protozoal counts. The LCP and LCPEO increased total tract digestibility of DM and organic matter and decreased CP digestibility compared with the control. Supplementation with EO did not affect total tract digestibility of dietary nutrients compared with the control or LCP. The LCP and LCPEO decreased urinary and fecal N excretions and increased milk N efficiency; nitrogen losses were not affected by EO. In this study, lowering dietary CP by 10 g/kg decreased urinary and fecal N excretion without affecting productivity. The supplementation of EO to LCP had only minor effects on rumen fermentation and did not affect productivity, digestibility and N excretion in lactating dairy cows.     

Milk fat depression and plasma lipids in dairy cows and goats

This study examines the effects of diets supplemented with various lipids selected to induce divergent milk fat content responses (including a milk fat depression) between dairy cows and goats on plasma lipid composition. The objective was to better understand the mechanisms behind the regulation of milk fat secretion in these two ruminant species. Twelve Holstein cows and 12 Alpine goats were fed a basal diet not supplemented (CTL) or supplemented with corn oil plus wheat starch (COS, 5% DM intake (DMI)), marine algae powder of Schizochytrium sp. (MAP, 1.5% DMI), or hydrogenated palm oil (HPO, 3% DMI), in a replicated 4 × 4 Latin square design, during 28 days. On day 27, blood samples were collected for lipid analysis. Plasma lipid classes were quantified by high-performance thin-layer chromatography, with triacylglycerol (TAG) and free fatty acid (FFA) fractions analysed for FA composition by GLC. Plasma molecular species of TAG and ceramides were determined by HPLC–high-resolution MS and by liquid chromatography–triple quadrupole, respectively. Irrespective of diet, plasma total lipid content was higher in cows than goats (+61%), and TAG concentration was higher in goats than cows (+157%). In cows, conversely to goats, COS increased the trans-10 C18:1 proportion in the free FA (+248%) and the TAG (+195%) fractions. In cows and goats, MAP induced increases in cholesterol esters, cholesterol and phospholipids compared to CTL and changes in the plasma free FA and FA of TAG profiles. In both ruminant species, the concentrations of the lipid fractions were unchanged by HPO compared to CTL. Our results point to species specificities and different diet effects in plasma concentrations and compositions of lipid fractions in cows and goats. These new data highlight how diets, that induce large variations in milk fat secretions, affect the plasma lipid classes available for milk fat synthesis.     

Effects of grazing willow fodder blocks upon methane production and blood composition in young sheep

A 79-day rotational grazing experiment was conducted over the summer and autumn of 2007 to compare effects of grazing willow (Salix spp.) fodder blocks, a combination of small trees (i.e., 1.0 m) and herbage, or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) control pasture on breath methane (CH₄) emissions, concentrations and solubility of CH₄ and sulphur hexafluoride (SF₆) tracer gas in blood, and haematology variables in young growing female sheep (i.e., hoggets). Measurements of gases in blood followed a double equilibration technique with two (n = 20) replicate per treatment. Ten ewe hoggets in each replicate were dosed on day 22 with intraruminal slow release SF₆ capsules, an inorganic tracer gas used to calculate CH₄ emissions. Breath samples were collected over 5-day periods in weeks 5 (period 1) and 11 (period 2). Total condensed tannin (CT) concentrations calculated in the diet selected by the willow fodder block sheep was 12 g CT kg/dry matter intake, with negligible amounts in control pasture hoggets. Compared to control pasture, grazing willow fodder blocks reduced CH₄ emission/kg metabolic body weight (BW^0.75) by 20% in period 1 (P<0.01), but not in period 2. Blood CH₄ concentrations (ng/mL blood) were similar for both groups on day 36, but higher (P<0.001) on day 76 for hoggets grazing willow fodder blocks, while a different trend was observed for SF₆ blood concentration being higher (P<0.01) on day 36 in hoggets grazing willow fodder blocks, but similar in both groups on day 76. Repeatability of blood CH₄ concentration was 75% in period versus 84% in period 2. Methane and SF₆ Ostwald solubility coefficients in blood were similar in both periods for sheep grazing willow fodder blocks and the control pasture. Hoggets grazing willow fodder blocks had lower BW gain (65 g/day), carcass weight (16.1 kg) and carcass fatness (9.2 mm) than hoggets grazing control pasture (102 g; 18.3 kg; 11 mm). Hoggets dosed with SF₆ capsules had lower (P<0.05) red blood cells, haemoglobin and haematocrit concentrations when grazing either willow fodder blocks or control pasture, while neutrophil (P=0.063), platelet (P=0.073) and monocyte (P=0.072), white blood cell and total lymphocyte counts (P<0.05) were higher for willow fodder block-fed hoggets than those fed the control pasture. Differences in the reduction in CH₄ emission between periods from grazing willow fodder blocks may be due to more willow leaf being eaten during the CH₄ measurement period in period 1 than in period 2.     

Intake,milk yield and grazing behaviour of strip-grazing Alpine dairy goats in response to daily pasture allowance

Grazing management has an important impact on dairy ruminants’ performance. References on the intake and milk yield of dairy goats under strip-grazing systems in temperate regions are scarce. In order to study the effect of pasture allowance on pasture intake (PI), milk yield and grazing behaviour, a trial was carried out in spring with 36 Alpine goats in mid-lactation. Three daily pasture allowances (PA=1.7, 2.6 and 3.5 kg dry matter (DM)/day, namely Low, Medium and High, respectively) were compared in a 3 × 3 Latin square design replicated six times during three successive 14-day periods. Goats individually received 268 g DM of concentrate twice daily at each milking and had access 11 h/day to pasture (from 0830 to 1600 h and from 1730 to 2100 h). Pasture intake increased with PA, and more so between Low and Medium than between Medium and High (+216 v. +101 g DM/kg DM of PA). Milk yield was lower on Low than on Medium and High (2.79 v. 3.13 kg/day), as were milk fat and protein yields. Grazing time averaged 476 min/day and was lowest on Low and greatest on Medium. Pasture intake rate was 30 g DM/h lower on Low and Medium than on High. It is concluded that under temperate conditions, when goats are supplemented with 536 g DM of concentrate and have enough access time to pasture (11 h/day), a medium pasture allowance close to 2.6 kg DM/day may be sufficient to maximise milk yield.     

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

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 ¹⁵N compared with feed, whilst urine was depleted in ¹⁵N 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.     

Rubber seed oil and flaxseed oil supplementation alter digestion,ruminal fermentation and rumen fatty acid profile of dairy cows

Rubber seed oil (RO) that is rich in polyunsaturated fatty acids (FA) can improve milk production and milk FA profiles of dairy cows; however, the responses of digestion and ruminal fermentation to RO supplementation in vivo are still unknown. This experiment was conducted to investigate the effect of RO and flaxseed oil (FO) supplementation on nutrients digestibility, rumen fermentation parameters and rumen FA profile of dairy cows. Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of four treatments for 8 weeks, including basal diet (CON) or the basal dietary supplemented with 4% RO, 4% FO or 2% RO plus 2% FO on a DM basis. Compared with CON, dietary oil supplementation improved the total tract apparent digestibility of DM, neutral detergent fibre and ether extracts ( P < 0.05). Oil treatment groups had no effects on ruminal digesta pH value, ammonia N and microbial crude protein ( P > 0.05), whereas oil groups significantly changed the volatile fatty acid (VFA) profile by increasing the proportion of propionate whilst decreasing total VFA concentration, the proportion of acetate and the ratio of acetate to propionate ( P < 0.05). However, there were no differences in VFA proportions between the three oil groups (P > 0.05). In addition, dietary oil supplementation increased the total unsaturated FA proportion in the rumen by enhancing the proportion of trans-11 C18:1 vaccenic acid (VA), cis-9, trans-11 conjugated linoleic acid (CLA) and α-linolenic acid (ALA) ( P < 0.05). These results indicate that dietary supplementation with RO and FO could improve nutrients digestibility, ruminal fermentation and ruminal FA profile by enhancing the VA, cis-9, trans-11 CLA and ALA composition of lactating dairy cows. These findings provide a theoretical basis for the application of RO in livestock production.     

Effects on ewe reproduction of grazing willow fodder blocks during drought

A grazing experiment was conducted in the summer/autumn of 2003 to determine the effect of grazing on willow fodder blocks at 6000 stems/ha during mating, relative to control ewes grazed on drought pasture, upon ewe production and reproduction. The fodder blocks contained a mixture of herbage and small trees. Grazing occurred over 10 weeks, from 19 February including three cycles of mating, with four groups of 100 ewes, comprising short drought pasture typical of drought pasture, long drought pasture typical of the pasture growing in the willow fodder blocks, short drought pasture with restricted access to willow fodder blocks (restricted access) and full access to willow fodder blocks (fenced on the willow fodder blocks all the time; full access). After mating, the four groups were joined and managed as one group until weaning in late November 2003. Ewe live weight (LW) and body condition score (BCS) change and reproductive rate at foetal ultra-sound scanning, lambing, docking and weaning were measured. Ewe wool production and staple length were measured at weaning. Short drought pasture had a pre-grazing mass of 1639 kg dry matter (DM)/ha with a dead matter content of 60%; typical of drought conditions. Herbage in the willow fodder blocks was similar to both control drought pastures (short and long) in nutritive value, with an organic matter digestibility (OMD) of 0.50. Tree yields were low in the fodder blocks, but they had higher concentrations of all secondary compounds, including 30 g condensed tannin (CT)/kg DM and OMD was higher, at 0.72. CT concentration was higher in the fodder block herbage than in short and long control drought pasture (5.0 g/kg versus 2.5 g/kg DM). Substantial LW loss occurred in the short control group (101 g/day), and reproductive rate was low, as would occur in severe drought conditions. Full access to fodder blocks lowered LW loss to 40 g/day and increased reproductive rate by approximately 20% units, with more ewes giving birth to twin lambs. Restricted access ewes had a low reproductive rate, similar to the short control group. Reproductive rate in full access treatment was slightly higher than in the long control group, despite similar calculated DM intakes in both groups. Calculated crude protein and CT intakes were higher for full access ewes than for any other groups, due to contributions from both the herbage and the trees; this may have increased the flow of undegradable dietary protein (UDP) to the small intestine and so have contributed to the increased fecundity of this group. Full access to willow fodder blocks proved beneficial in increasing ewe reproductive rate. However, both pasture and trees need to be managed as a tree/pasture system in order to produce herbage of higher nutritive value and more efficiently utilise willow fodder blocks as a supplementary feed.     

Effects of spent coffee grounds on production traits,haematological parameters,and antioxidant activity of blood and milk in dairy goats

Spent coffee ground (SCG) is a byproduct of coffee beverage preparation and a potential source of carbohydrate, protein, and phenolic compounds for livestock feeding. In this study, the effects of SCG supplementation in the diet of lactating goats on milk production traits and health status were studied. The antioxidant status of blood and milk was also evaluated. Twenty-four Saanen goats were fed a total mixed ration containing commercial concentrate, soybean, and haylage; they were divided into three groups: control diet (CON), SCG50 (50 g/d SCG), and SCG100 (100 g/d SCG). The experiment lasted 6 weeks. Linear and quadratic contrasts were used to evaluate the effects of the byproduct doses. SCG supplementation did not affect milk production, but influenced some milk fatty acids. SCG supplementation increased the contents of C18:1, cis-9, trans-11 C18:2, odd and branched-chain fatty acids, and total conjugated linoleic acid. Most of the haematological and biochemical parameters were within the physiological range for goats. The basophil, eosinophil, and glucose contents were quadratically affected by SCG, whereas platelet count increased linearly with the SCG dose. The SCG supplementation had a positive effect on the blood antioxidant status, as evidenced by an increase in ferric reducing antioxidant power and a decrease in malondialdehyde. The SCG supplementation had no effect on the milk antioxidant status. The results show that SCG (up to 100 g/d) did not negatively affect milk production and health status in goats. However, quadratic effects on some antioxidant and biochemical parameters suggest that further investigations are necessary, especially with regard to the optimisation of the supplement dose.     

Effects of medium-chain fatty acid supplementation on performance and rumen fermentation of lactating Holstein dairy cows

Medium-chain fatty acids (MCFAs) have antimicrobial properties and cause negative or positive effects on animal performance depending on its dosage. We hypothesized that MCFA supplementation at a lower dose (i.e., 0.05–0.2% of dietary DM) would increase rumen pH and milk production without decreasing nutrient digestibility which is typically observed with the higher inclusion rates (i.e., >1% of dietary DM). The objective of this study was to evaluate the effects of MCFA supplementation at a lower dose on productivity, plasma energy metabolite concentrations, apparent total tract nutrient digestibility, rumen fermentation, and rumen microbial profile of lactating dairy cows. Thirty (n = 8 primiparous, n = 22 multiparous) Holstein cows in mid-lactation (637 ± 68.5 kg of initial BW, 98.5 ± 27.4 d in milk; mean ± standard deviation) were used in a crossover design with two 28-d periods. The MCFA supplement, consisted of 25% MCFA (containing 32% C8:0, 21% C10:0, 47% C12:0 on DM basis) and 75% carrier ingredients, was fed at 0.25% of dietary DM replacing dry ground corn in control (CON). Total inclusion of MCFA was 0.063% of dietary DM. No differences were observed in DM intake, apparent total tract nutrient digestibility and BW change between MCFA and CON. Milk and milk component yields did not differ between treatment groups. The MCFA supplementation tended to have higher minimum rumen pH (5.66 vs. 5.54), and decreased daily fluctuation range of rumen pH (1.17 vs. 1.40) compared to CON. However, the duration of acidosis (pH < 5.8, min/d) did not differ between treatment groups and ruminal total volatile fatty acid concentration and its profile did not differ between treatment groups. For rumen microbiota, the Chao1 index of bacterial community tended to be lower (10.9 vs. 11.6) whereas the Shannon index did not differ (0.91 vs. 0.93) in MCFA compared to CON, and both indices did not differ for archaeal and protozoan communities between treatment groups. The relative abundance of Methanobrevibacter gottschalkii increased when supplemented with MCFA (5.14 vs. 4.92%). These results suggest that supplementation of MCFA at 0.063% dietary DM may not affect overall animal performance or total tract nutrient digestibility, but decrease the daily range of pH and the bacterial richness in the rumen.     

Bacterial concentrations in bedding and their association with dairy cow hygiene and milk quality

Comparison of bacterial counts (BCs) among common bedding types used for dairy cows, including straw, is needed. There is concern that the microbial content of organic bedding is elevated and presents risks for dairy cow udder health and milk quality. The objectives of this study were to investigate: (1) % DM and BCs (Streptococcus spp., all gram-negatives and specifically Klebsiella spp.) in different types of bedding sampled, and to investigate housing and farm management factors associated with % DM and BCs; (2) if bedding type was associated with hygiene of cow body parts (lower-legs, udder, upper-legs and flank) and housing and management factors associated with hygiene and (3) bedding types associated with higher BCs in cow milk at the farm level and bulk tank milk and management factors that were associated with highest BCs. Seventy farms (44 free-stall and 26 tie-stall) in Ontario, Canada were visited 3 times, 7 days apart from October 2014 to February 2015. At each visit, composite samples of unused and used bedding were collected for % DM determination and bacterial culture. Used bedding samples were collected from the back third of selected stalls. Data were analyzed using multivariable linear mixed models. Bedding classification for each farm were: new sand (n = 12), straw and other dry forage (n = 33), wood products (shavings, sawdust; n = 17) and recycled manure solids (RMSs)-compost, digestate (n = 8). In used bedding, across all bedding samples, sand was driest, compared to straw and wood, and RMS; higher % DM was associated with lower Streptococcus spp. count. Streptococcus spp. and all Gram-negative bacteria counts increased with increasing days since additional bedding was added. Gram-negative bacteria counts in used bedding varied with type: RMS = 16.3 ln colony-forming units (cfu)/mL, straw = 13.8 ln cfu/mL, new sand = 13.5 ln cfu/mL, and wood = 10.3 ln cfu/mL. Klebsiella spp. counts in used bedding were lower for wood products (5.9 ln cfu/mL) compared to all other bedding types. Mean cow SCC tended to be higher on farms with narrower stalls. Farms with mattress-based stalls had a higher prevalence of cows with dirty udders compared to those using a deep bedding system (often inorganic sand). Wider stalls were associated with lower bulk milk bacteria count. Lower % DM of used bedding was associated with higher bulk milk bacteria count. In conclusion, bedding management may have a profound impact on milk quality, bacterial concentrations in the bedding substrates, and cow hygiene.     

Mixed grazing systems of goats with cattle in tropical conditions: an alternative to improving animal production in the pastureq

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 over 5-day periods. This pattern was replicated in space for a second set of four subplots and in time for six successive cohorts of animals (bands 1 to 6). The ADG of goats in mixed grazing conditions was higher than controls irrespective of the infection status (32.6 v. 18.4 g/day for MI v. CI; 44.2 v. 33.5 g/day for MnI v. CnI). Concomitantly, the average biomass was lower for mixed grazing animals compared with controls (174 v. 170 for MI and MnI; 235 v. 208 for CI and CnI, respectively), suggesting better use of the sward. For daily BW gain (g/kg DM), mixed grazing also yielded better results than the control (1.88 v. 0.52 g BW/kg DM per day for MI v. CI; 2.08 v. 1.47 g BW/kg DM per day for MnI and CnI). Mixed grazing of goats and heifers offers a promising alternative for increasing goat and overall animal production as well as improving the management of pastures.     

Short-term physiological responses to moderate heat stress in grazing dairy cows in temperate climate

Even in temperate climate regions, an increase in ambient temperature and exposure to solar radiation can cause heat stress in lactating dairy cows. We hypothesised that grazing dairy cows exhibit short-term physiological changes due to increasing heat load under moderate climate conditions. Over two consecutive summers, 38 lactating Holstein dairy cows were studied in a full-time grazing system. Data were collected in 10 experimental periods of up to three consecutive days with a moderate comprehensive climate index (CCI). The individual animals’ vaginal temperature (VT), heart rate, and locomotor activity data were automatically monitored with sensors. Blood samples and proportional whole milk samples were collected at afternoon milking. The concentrations of beta-hydroxybutyrate, glucose, non-esterified fatty acids, urea nitrogen, plasma thyroxine and triiodothyronine were analysed in blood plasma, and fat, protein, lactose, urea nitrogen, cortisol, Na⁺, K⁺, and Cl^? concentrations were analysed in milk. The daily distribution of VT recordings greater than 39 °C showed a circadian rhythm with a proportion of recordings of 2% and lower during the night and a percentage of 10% or higher in the afternoon. The cows’ maximal daily vaginal temperature (VT_MAX) between 0830 and 1430 h was positively related to the mean daily CCI in the same time period (CCI_MEAN; mean and SD 23.6 ± 5.4 °C). Cows with greater VT_MAX had an increased mean heart rate, plasma glucose and milk cortisol concentrations and decreased concentrations of plasma thyroxine and triiodothyronine. The concentration of Na⁺ in milk was lower, and the concentration of K⁺ in milk tended to be higher in cows with increased VT_MAX. For beta-hydroxybutyrate, non-esterified fatty acids and urea nitrogen concentrations in plasma and fat and lactose concentrations in milk no relationships were found in terms of increasing VT. For milk urea nitrogen and protein concentrations, the proportion of total variance explained by inter-individual or -period variance was high. In conclusion, changes observed in milk and blood likely reflected short-term physiological responses to moderate heat stress. In particular, milk cortisol and Na⁺ may be useful traits for timely monitoring of heat stress in individual cows because their inter-individual variances were relatively small and samples can be collected non-invasively.     

Increased diet viscosity by oat β-glucans decreases the passage rate of liquids in the stomach and affects digesta physicochemical properties in growing pigs

Rheological properties of digesta play a role in digesta passage kinetics through the gastrointestinal tract, in turn affecting nutrient absorption kinetics. Therefore, we studied the effects of diet viscosity on digesta passage and physicochemical properties in pigs. Twenty male growing pigs (35 kg body weight at the start) were assigned to one of five diets with increasing dietary concentrations of β-glucans (BG; from 0 % to 10 %), in exchange for maize starch. After a 17-day adaptation period, pigs were euthanised and the mean retention time (MRT) of digesta solids (TiO₂) and liquids (Cr-EDTA) in the stomach, and proximal and distal half of the small intestine was quantified. In the stomach, the MRT of liquids, but not of solids, increased when dietary BG level increased (6 min per % dietary BG, P = 0.008 and R² = 0.35). Concomitantly, stomach DM content (5 g/kg per % dietary BG, P < 0.001 and R² = 0.53) and apparent digesta viscosity (56 Pa × s at 1/s shear rate per % dietary BG, P = 0.003 and R² = 0.41) decreased. In the proximal half of the small intestine, no effects of dietary BG level were observed. In the distal half of the small intestine, water-binding capacity (WBC) of digesta increased (0.11 g/g digesta DM per % dietary BG, P = 0.028 and R² = 0.24) and starch digestibility decreased (0.3% per % dietary BG, P = 0.034 and R² = 0.23) when dietary BG level increased. In the colon, apparent digesta viscosity at 45/s shear rate increased (0.1 Pa × s per % dietary BG, P = 0.03 and R² = 0.24) in the proximal half of the colon, and digesta WBC increased (0.06 g/g digesta DM per % dietary BG, P = 0.024 and R² = 0.26) in the distal half of the colon when dietary BG level increased. To conclude, increasing dietary BG level caused the MRT of liquids, but not that of solids, to increase in the stomach, resulting in reduced separation of the solid and liquid digesta fractions. This caused dilution of the stomach content and reduction in digesta viscosity when dietary BG levels increased. Effects of dietary BG level on physicochemical properties in the proximal small intestine were absent and may have been due to a low DM content. The WBC of digesta in the distal small intestine and colon increased when dietary BG level increased, as did apparent digesta viscosity in the proximal colon. This likely reflects the concentration of BG in digesta when moving through the gastrointestinal tract.     

Effects of sodium selenite and coated sodium selenite on lactation performance,total tract nutrient digestion and rumen fermentation in Holstein dairy cows

Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.     

Effects of dietary crude protein concentration on animal performance and nitrogen utilisation efficiency at different stages of lactation in Holstein-Friesian dairy cows

Nitrogen (N) excretion from livestock production systems is of significant environmental concern; however, few studies have investigated the effect of dietary CP concentration on N utilisation efficiency at different stages of lactation, and the interaction between dietary CP levels and stages of lactation on N utilisation. Holstein-Friesian dairy cows (12 primiparous and 12 multiparous) used in the present study were selected from a larger group of cows involved in a whole-lactation study designed to examine the effect of dietary CP concentration on milk production and N excretion rates at different stages of lactation. The total diet CP concentrations evaluated were 114 (low CP), 144 (medium CP) and 173 (high CP) g/kg DM, with diets containing (g/kg DM) 550 concentrates, 270 grass silage and 180 maize silage. During early (70–80 days), mid- (150–160 days) and late (230–240 days) lactation, the same 24 animals were transferred from the main cow house to metabolism units for measurements of feed intake, milk production and faeces and urine outputs. Diet had no effect on BW, body condition score, or milk fat, protein or lactose concentration, but DM intake, milk yield and digestibilities of DM, energy and N increased with increasing diet CP concentration. The effect of diet on milk yield was largely due to differences between the low and medium CP diets. Increasing dietary CP concentration significantly increased urine N/N intake and urine N/manure N, and decreased faecal N/N intake, milk N/N intake and manure N/N intake. Although increasing dietary CP level significantly increased urine N/milk yield and manure N/milk yield, differences in these two variables between low and medium CP diets were not significant. There was no significant interaction between CP level and stage of lactation on any N utilisation variable, indicating that the effects of CP concentration on these variables were similar between stages of lactation. These results demonstrated that a decrease in dietary CP concentration from high (173 g/kg DM) to medium level (144 g/kg DM) may be appropriate for Holstein-Friesian dairy cow to maintain milk production efficiency, whilst reducing both urine N and manure N as a proportion of N intake or milk production.     

Season of grazing and stocking rate interactively affect fuel loads in Baikiaea plurijuga Harms woodland in northwestern Zimbabwe

Wildfire is a major disturbance in Baikiaea plurijuga Harms woodland savannas. We tested the hypothesis that the timing and intensity of herbivory influence fuel loads. We used three stocking rates namely light (three cows and four goats ha^?1), medium (six cows and eight goats ha^?1) and heavy (eleven cows and sixteen goats ha^?1) and three times of grazing namely early‐, middle‐ and late‐growing seasons. Season of grazing and stocking rate influenced herbaceous phytomass. Phytomass was generally the highest (53.5 g DM m^?2) in paddocks grazed during the early growing season and the lowest (27.8 g DM m^?2) in those grazed during the late growing season. Phytomass was also generally the highest (40.4 g DM m^?2) in lightly stocked paddocks and the lowest (32.7 g DM m^?2) in heavily stocked ones. Litter mass was the lowest (160.8 g DM m^?2) in paddocks grazed during the early season whereas there were no differences in ungrazed paddocks and those grazed during either mid‐ or late growing seasons (205.4 g DM m^?2). There was a negative relationship between litter mass and stocking rate. Baikiaea Benth. woodlands should be grazed during either the mid‐ or late‐growing season at stocking rates greater than 0.1 LU ha^?1 to reduce grass fuel loads.     

The tungsten-tungsten triple bond. XV. Synthesis,structure and reactivity of 1,2-W2[CH(SiMe3)2]2(NMe2)4: the remarkable inertness of a sterically-encumbered tungsten-amido complex

Addition of 1,2-W₂Cl₂(NMe₂)₄(W≡W) to a toluene slurry of LiCH(SiMe₃)₂(2 equiv) results in the formation of 1,2-W₂[CH(SiMe₃)₂]₂(NMe₂)₄(W≡W) (I) in 79% isolated yield. Compound I has been characterized by ¹H and ¹³C NMR, IR, elemental analysis and single-crystal X-ray diffraction. The molecule exists exclusively in the gauche conformation in solution and in the solid state with WW = 2.320(1) Å. Compound I is very sterically encumbered as evidenced by: (1) large WWC angles, 110°, at the disyl ligand; (2) skewing of the NC₂ planes of the NMe₂ ligands off the WW vector; (3) anomalously large barriers to WNM₂ bond rotation in solution; (4) the inertness of I towards CO₂ and alcohols. However, compound I reacts with acetic anhydride to form 1,2-W₂[CH(SiMe₃)₂]₂(O₂CMe)₄(W≡W) (II) in 31% isolated yield. Compound II has been characterized by ¹H and ¹³C NMR, IR, and elemental analysis. The mechanistic implications of these studies with regard to alcoholysis and CO₂ insertion reactions of other 1,2-W₂R₂(NMe₂)₄ compounds are discussed. Crystal data for 1,2-W₂[CH(SiMe₃)₂]₂(NMe₂)₄ at −140°C: space group P2₁/n, a = 12.555(3), b = 18.699(5), c = 15.214(4) Å, β = 95.24(1)° and Z = 4.