Effects of heather and oat supplementation on gastrointestinal nematode infections and performance of grazing Cashmere goats

This work aimed to evaluate the effects of tannin-containing heather (Calluna vulgaris, Erica spp.) and energy (oats, Avena sativa) supplementation, combined or not, on feed intake, gastrointestinal nematode infections and performance of goats grazing mountain grasslands. Two successive experiments were established across one grazing season on four paddocks. The first (late April to early August, Period 1) involved two treatments, i.e., supplementation with heather (+H) vs. non-supplementation (−H), each randomly allocated to two paddocks. The second (mid-August to mid-November, Period 2) consisted on four treatments in a 2 × 2 factorial design, i.e., supplementation with heather and oats (+H+O), only heather (+H−O), only oats (−H+O), and no supplementation (−H−O). Results from Period 1 indicated that faecal nematode egg counts (FEC) were lower in +H goats (50% less in August), achieving more favourable live weight (LW) and body condition changes than −H goats. Total dry matter intake (DMI) in June was similar between treatments, with heather accounting for 0.21 of +H goat diets. Kids FEC and LW gains were not affected by heather supplementation. In Period 2, both heather and oat supplementation reduced FEC (45 and 61%, respectively) and improved goat performance, without an interaction between both factors. Total DMI in October was higher in +H+O compared to other treatments (48 vs. 30 g DM kg LW^−0.75 d⁻¹; P < 0.01). Rumen ammonia concentration was lower (P < 0.001) in +H than in −H goats, and in +O than in −O goats, whereas that of volatile fatty acids (VFA) was not affected by treatments, though the molar proportions of some VFA were modified. It is concluded that the combination of both supplements (tannins and energy) contributes to reduce gastrointestinal nematode parasitism and increases goat performance, allowing a lower dependence on conventional chemotherapy.     

Effect of high tannin grain sorghum on gastrointestinal parasite fecal egg counts in goats

The objective of three experiments was to determine the influence of high condensed tannin (CT) grain sorghum on gastrointestinal parasite fecal egg counts (FEC). Sixteen naturally infected Boer crossbred mixed-sex goats were used. Animals that were supplemented with grain daily were removed from pasture and placed in individual pens and fed treatment diets for 21 or 14 days (Experiment 3). Goats were allowed ad libitum access to water and diets containing high or low CT cracked grain sorghum. On day 0 and every 7 days thereafter, PCV, FEC and FAMACHA^® eyelid color scores (EYE; Experiment 1 only) were recorded. For Experiment 1, percentage of animals dewormed, PCV and EYE were not influenced by treatment and averaged 13.6 ± 4.5% per treatment period, 23.4 ± 0.8% and 3.2 ± 0.12, respectively, for all animals. The FEC increased after day 0 for control but not high tannin grain sorghum fed goats (treatment by day interaction, P < 0.02). As expected, EYE and PCV were negatively related (r = −0.45; P < 0.0005). For Experiment 2, there was no influence of diet on PCV or FEC, but there was an effect of day on FEC (P < 0.002) in which all goats had higher FEC on day 0 (1956 ± 219 eggs/g) than any other sampling day. For Experiment 3, there was no effect of feeding high CT grain sorghum on FEC (2992 ± 591 eggs/g) or PCV (25.1 ± 0.5%). In these studies, high CT grain sorghum did not consistently influence FEC and did not impact PCV or number of animals requiring chemical anthelmintic treatment.     

Diet selection and live-weight changes of two breeds of goats grazing on heathlands

Diet selection, live-weight changes and productivity per hectare of two breeds of goats (Cashmere and local Celtiberic) managed in natural vegetation dominated by heather, and the effect of stocking rate (high or low) in the Cashmere breed, were studied during four grazing seasons. Breed had a significant (P < 0.01) effect on the available biomass and its components over the experimental period as a consequence of the differences in dietary components selected by the animals. Local goats produced a greater reduction in short and tall heather and in the percentage of leaves in the tall heather. Live-weight changes were significantly (P < 0.001) different between breeds. Over all experimental years Cashmere goats maintained weight under both low and high stocking rate (4 and - 1 g/day respectively), while local Celtiberic goats lost 30 g/day.Across all grazing seasons and experimental years stocking rate did not significantly affect individual live-weight changes of Cashmere goats. Productivity per hectare did not differ significantly (P>0.05) between high ( - 0.6 kg/ha) and low stocking rate treatments (4.1 kg/ha). However it was significantly (P < 0.001) worse for the local breed treatment ( - 51 kg/ha).As a consequence, in these vegetation communities with low abundance and poor quality of herbaceous plants it will be impossible to develop sustainable systems from the animal production point of view, and their management would need to be integrated during the grazing season by alternating with vegetation communities with better quality.     

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.     

Changes in heathland vegetation under goat grazing: effects of breed and stocking rate

Questions: How are heathland vegetation dynamics affected by different goat grazing management? Location: Cantabrian heathlands in Illano, Asturias, northern Spain. Methods: During 4 years, vegetation dynamics (structural composition, canopy height and floristic diversity) were studied under three goat grazing treatments with three replicates: high stocking rate (11.7 goats ha^?1) with a local Celtiberic breed, and high (15 goats ha^?1) and low (6.7 goats ha^?1) stocking rates with a commercial Cashmere breed. Results: The relative cover of woody plants, particularly heather species, decreased more while herbaceous cover increased more under local Celtiberic than under Cashmere breed grazing. Within Cashmere treatments, the cover and height of live shrubs decreased more and the herbaceous cover increased more under high than under low stocking rate. Redundancy analysis showed a significant effect of treatment × year interaction on floristic composition. Greater species richness was recorded under local goat grazing, but Shannon diversity index fell in the fourth year on these plots because of dominance by two grass species. Conclusions: Local Celtiberic goat grazing at such a high stocking rate (11.7 goats ha^?1) hinders the development of sustainable systems on these heathlands, both in environmental and productive terms, owing to the limitations in soil fertility. Nevertheless, Celtiberic goats could be useful for controlling excessive shrub encroachment and reducing fire hazard. Cashmere goat grazing at high stocking rate promoted the highest Shannon diversity by generating a better balance between woody and herbaceous plants, while shrub dominance was not altered under the low stocking rate.     

Effect of a single subcutaneous injection of melatonin on estrous response and conception rate in goats

The objectives of this study were to evaluate the effect of a single subcutaneous injection of melatonin, on estrous induction and conception rate during the non-breeding season at different times of the year. In Experiment 1 the melatonin powder was dissolved in an oily vitamin A, D, E solution and injected subcutaneously randomly to goats in two dose treatment groups of 20 mg (MLT-20; n = 20) and 40 mg (MLT-40; n = 20) in January (winter). Twenty does were injected with 1 ml vitamin A and served as the control. In the MLT-20 treated goats 70% of the does were in estrus within 20.0 ± 2.0 days, whereas in the MLT-40 group 85% of the does were in estrus within 15.5 ± 2.5 days and 100% and 80% of the does, respectively, conceived on mating with the bucks. Only 10% of the untreated control does exhibited estrus, but none conceived. The breeding season was thus initiated earlier by 1–1.5 months in the treated goats. In Experiment 2, goats were treated with similar MLT-20 and MLT-40 treatments in May (spring), with 20 goats in each treatment group and 20 control goats. The proportion of goats that responded to the melatonin treatments was 80% and 90% in the MLT-20 and MLT-40 treatments, respectively, with no significant differences recorded regarding the estrous response. However, in the MLT-20 treatment group the estrous induction interval was significantly longer (P < 0.05), compared to the MLT-40 treatment. The pregnancy rates were not significantly different for the MLT-20 and MLT-40 treatments, with melatonin resulting in significantly higher pregnancy rates than in the control (88.4% versus 33.3%) and the breeding season initiated 2 months earlier. It could be concluded that a single subcutaneous injection of melatonin can initiate the breeding season (irrespective of the season of the year) earlier by 1–2 months in goats and this could be advantageous when using accelerated breeding systems.     

A study on ectoparasites of sheep and goats in eastern part of Amhara region,northeast Ethiopia

A study on ectoparasites of small ruminants was carried out in three districts (woredas) of the eastern part of Amhara Regional State, Ethiopia, from November 2003 to March 2004, with the objectives of determining the prevalence of ectoparasites and identifying the potential risk factors associated with the problem. Out of 752 sheep and 752 goats examined, 50.5% of sheep and 56.4% of goats were infested with one or more ectoparasites. The ectoparasites identified in sheep were Damalina ovis (38.5%), Melophagus ovinus (12.5%), tick infestations (3.4%) and Linognathus spp. (2.4%). In goats, parasites such as Linognathus spp. (28.3%), ticks (22.2%), sarcoptic mites (6.1%) and Ctenocephalides spp. (8.1%) were identified. The prevalence of M. ovinus and D. ovis infestations in sheep were significantly (p < 0.05) higher in the highlands than both lowlands and midlands, which were almost similar. In goats, the risk of sarcoptic mange infestation in lowland and midland was 4.6 and 5.0 times higher than the highlands, respectively. The prevalence of Linognathus spp. in goats was significantly (p < 0.05) higher in the highlands than the lowlands. Both in sheep and goats, no significant difference between young and adult age groups was observed for any ectoparasites except for D. ovis in sheep in which adults (42.2%) were more affected than young animals (29.9%). The goats with poor body condition were 4.3 times at risk for sarcoptic mange (OR = 4.3, p < 0.05), Linognathus spp. (OR = 2.1, p < 0.05) and tick (OR = 1.6, p < 0.05) infestation than goats of good body condition. On the contrary, no significant variation (p > 0.05) in ectoparasite infestation of sheep was observed in relation to body condition. Favorable climates, poor management, poor awareness of farmers and poor animal health extension services are believed to have contributed for the widespread occurrence of ectoparasites.     

Short-term glutamate administration positively affects the number of antral follicles and the ovulation rate in cyclic adult goats

The acute effects of short-term glutamate administration on the number of antral follicles and ovulation rate were examined in adult goats. Neither live weight (44.5 ± 1.3 kg) nor body condition (3.3 ± 0.8 units) differed between the control (untreated) and glutamate-treated (0.175 mg/kg) animals (p > 0.05). However, the number of antral follicles (3.4 vs. 2.1, p = 0.05) and ovulation rate (2.5 vs. 1.5, p = 0.05) was higher in the glutamate-administered group than in the controls.     

Grazing of cover crops in integrated crop-livestock systems

Conventional agriculture is specializing rapidly into the management of few monoculture crops, threatening crop diversity and questioning the sustainability of extensive cropping systems. The grazing of cover crops in integrated crop-livestock systems could be a feasible biologically based technology to restore crop diversity and mitigate ecological issues in cropping systems. However, there is limited evidence on plausible synergies or trade-offs for the practice, and about how grazing plans could affect the herbage production and services from cover crops. This work assessed the effects of cattle grazing on the primary and secondary production of annual ryegrass (Lolium multiflorum) in an integrated ryegrass–soybean rotation system. Specifically, the prediction for synergistic effects of cattle grazing on the ryegrass herbage production, residual crop cover and animal performance were tested in a 2-year (2014 and 2015) study comprising a randomized complete block design of four grazing intensity treatments, replicated three times. A no-cattle grazing treatment (NG), used as control, or continuous grazing with Holstein heifers (~ 220 kg live weight) at targeted sward heights of 5, 10, 15 and 20 cm (hereafter referred as G₅, G₁₀, G₁₅ and G₂₀, respectively) was applied to ryegrass plots. The herbage production and residual herbage cover of ryegrass, and the average daily gain (ADG, kg/day) and live weight gain per hectare (LWG, kg/ha) of heifers were analyzed by ANOVA (P < 0.05) and compared by the Tukey_HSD test (P < 0.05). Regression models were used to estimate relationships between herbage production, animal performance and sward height. The herbage production was 60% higher (P < 0.01) for the grazing treatments compared to NG. The residual herbage for G₁₅ and G₂₀ was not different than that for NG and increased linearly as sward heights increased, reaching highest values for G₁₅ and G_20. Maximum ADG was 1.10 kg/day for ryegrass grazed at a 20.6 cm height, whereas maximum LWG was 427 kg/ha for ryegrass grazed to a 16.1 cm height. The results support the hypothesis for synergistic effects of using annual ryegrass as a dual forage and service cover crop. Moderate grazing intensity to sward height of 12–18 cm with continuous stocking led to optimized forage production and utilization by dairy heifers.     

Initiation of the breeding season in ewe lambs and goat kids with melatonin implants

Sixty-eight female and 4 male lambs of the Chios breed born in autumn (September–October) and 48 female and 4 male kids of the Damascus breed also born in autumn (November), were used to evaluate the effect of melatonin implants (Regulin^®) on the initiation of the breeding season. For each species and sex, half of the animals were either left untreated to serve as controls (C) or received ear implants (females one and males two implants) of melatonin (MEL) in May (spring). Each C and MEL group of females was kept separately and away from males for 5 weeks after implantation and then, C and MEL males were joined with the respective groups for 45 (sheep) and 35 days (goats). Animals not conceiving during the early June–July breeding season, were mated again in September (natural breeding season). The reproductive performance and the 60-day milk yield of animals giving birth during the two seasons were compared. Early in the season (mid November–December), significantly more MEL than C ewes and goats gave birth (75.5% versus 23.5%, p < 0.01; 70.8% versus 37.5%, p < 0.05, respectively). For both species, most of the other characteristics examined were significantly affected by season, but not by treatment. Females giving birth early in the season were approximately 80 days younger at parturition and recorded a lower body weight at mating than those giving birth in the natural February–March season. In the first mating period, the animals mated and conceived had similar body weights to those not mated. The natural, compared with the early June–July mating season, was associated in sheep with higher litter weight at birth (7.0 kg versus 5.8 kg, p < 0.05) and in sheep and goats with a higher number (p < 0.05) of offspring born live (1.78 versus 1.38; 2.0 versus 1.61, respectively) and weaned (1.74 versus 1.36; 1.82 versus 1.35, respectively). Total litter size at birth and 60-day milk yield after weaning, were not significantly different between the two seasons. It could be concluded that melatonin implants administered during the last month of spring in autumn-born female Chios sheep and Damascus goats, advanced the initiation of their breeding season by about 80 days when joined with young males also treated with melatonin implants. The overall reproductive performance and milk yield of animals breeding early, was satisfactory and comparable to that of animals breeding in the natural breeding season.     

Effects of total nonstructural carbohydrates and nitrogen balance on voluntary intake of goats and digestibility of gamagrass hay harvested at sunrise and sunset

We evaluated differences in composition of Iuka gamagrass (Tripsacum dactyloides L.) hay harvested at 06:00 (AM harvest) or 18:00 h (PM harvest), and measured how protein supplementation and time of harvest interact to affect the voluntary intake, digestibility, and N balance of goats. Boer cross wethers (n = 28; 24 kg) were randomly assigned to be fed supplement (310 g/kg of crude protein (CP), fed at 110 g/kg of dry matter (DM) intake, 14 goats) or no supplement (14 goats). Within supplemented or not supplemented groups, goats were randomly assigned to a crossover design of AM harvest (seven goats) or PM harvest (seven goats), and housed individually in metabolism crates with free access to water and mineral blocks. They were fed twice daily, with supplement offered 30 min prior to the morning feedings. After a 7-d adaptation, voluntary intake (goats were offered 1100 g/kg of previous day's intake) was measured for 14 d, followed by a 4-d adjustment phase to equalize DM offered between periods, and finally a 5-d digestion and balance phase. After Period 1, goats were switched to their new hay harvest times, and the protocol was repeated. Compared to the AM harvest, the PM harvest had higher (P<0.03) proportions of total nonstructural carbohydrates (TNC, 70.8 g/kg DM versus 59.0 g/kg DM), monosaccharides (37.0 g/kg DM versus 28.6 g/kg DM), di- and polysaccharides (18.5 g/kg DM versus 15.4 g/kg DM) and less neutral detergent fiber (NDF, 700 g/kg versus 710 g/kg). Crude protein (79 g/kg DM) and starch (15.2 g/kg DM) were similar for the PM and AM harvest. Dry matter digestibility was higher (P<0.03) for the PM versus AM harvests (555 g/kg DM versus 531 g/kg DM) and for supplemented versus not supplemented (563 g/kg DM versus 522 g/kg DM). Voluntary gamagrass DM intake (550 g/d versus 548 g/d) and calculated total digestible DM intake (327 g/d versus 313 g/d) were similar for the PM and AM harvest. However, total digestible DM intake during the digestion and balance phase was higher (P<0.01) for the PM versus AM harvest (317 g/d versus 299 g/d). Time of harvest did not affect N intake, digestion, or calculated retention. Compared to no supplementation, the supplement improved (P<0.01) N digestion (6.1 g/d versus 3.7 g/d) and retention (2.2 g/d versus 1.1 g/d). The PM harvest increased DM digested, largely TNC and digestible DM intake by goats due to increased TNC and not because of a 2% increase in DM intake. Providing a protein supplement had very limited effects on intake and digestibility of gamagrass.     

Effect of supplementing Napier grass (Pennisetum purpureum) with Madras thorn (Pithecellobium dulce) on intake,digestibility and live weight gains of growing goats

A study was carried out in Coastal Kenya to evaluate the effect of supplementing Napier grass (Pennisetum purpureum) based diet with increasing level of Madras thorn (Pithecellobium dulce) on feed intake, digestibility and live weight changes of growing goats. Fifteen small East African goats 6 months old on average were randomly allocated to five treatments. Napier grass was either offered alone (control) or supplemented with 7.5, 15, 22.5 and 30 g DM/kg W^0.75 of Madras thorn. Supplementing with Madras thorn up to 22.5 g DM/kg W^0.75 had no (P > 0.05) significant effect on the intake of the basal diet, however there was a 29% depression in the intake of the basal diet at 30 g DM/kg W^0.75 level of supplementation. A (P < 0.05) increase significant in the TDMI from 242 for the control to 258, 302, 357 and 458 g/kg DM, was recorded for 7.5, 15, 22.5 and 30 g DM/kg W^0.75, respectively. Supplementation also resulted in increase (P < 0.05) in DM and OM digestibility. Feed N, N retained and loss increased linearly with increase in supplementation. Positive N balance was recorded for all goats 0.2, 1.4, 2.5, 3.2 and 3.6 g/day for control, 7.5, 15, 22.5 and 30 g DM/kg W^0.75, respectively. Goats fed the control diet lost a mean of 8 g BW/day while those supplemented with 7.5, 15, 22.5 and 30 g DM/kg W^0.75 gained 8, 23, 43 and 44 g/day, respectively. The use of Madras thorn forage as a protein supplement for goats could be an affordable source, especially to the resource-constrained farmers in the tropics.     

Effects of feed intake on enteric methane emissions from sheep fed fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) forages

Published analyses of enteric methane (CH₄) emissions from sheep and cattle show an inverse relationship between feed intake and CH₄ yield (g CH₄/kg dry matter (DM) intake), which suggests opportunities for reducing CH₄ emissions from feed eaten and per unit of animal production. Most relationships between feed intake and CH₄ yield have been based on animals fed conserved feeds, especially silages and grains. Our research is a series of experiments with fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne; ryegrass) forages fed to sheep at a range of feed intake levels. This study was comprised of four experiments where good quality freshly harvested white clover or ryegrass were fed to sheep over a three-fold range in DM intake, and CH₄ emissions were measured in respiration chambers for two consecutive days in each experiment. Measurements were made from 16 sheep in Experiment 1 (fed at 1.6 × metabolizable energy requirements for maintenance; ME_m), 28 sheep in Experiment 2 (at 0.8 and 2.0 × ME_m), eight sheep and two measurement periods in Experiment 3 (at 1.6 × ME_m), and 30 sheep in Experiment 4 (fed at 0.8, 1.2, 1.6, 2.0 and 2.5 × ME_m). Prior to each experiment, sheep had a 10 d acclimatization period to diets. Apparent digestibility was measured over 7 d from sheep in Experiments 1, 3 and 4, along with collection of rumen digesta for volatile fatty acid (VFA) determination. Although CH₄ yields differed when sheep were fed white clover or ryegrass at similar intakes, the differences were inconsistent and mean values similar across all experiments. This, and a similar structure of all experiments, enabled combined analysis of data from all four experiments using the restricted maximum likelihood (REML) procedure to estimate effects of feed intake level on digestibility, digestible nutrient intake, gas emissions, and VFA concentrations in the rumen. The REML analysis showed that when DM intake increased from 0.40 to 1.60 kg/d, the predicted responses were an increase in CH₄ production (g/d) of 187% (12.4–35.6 g/d; P<0.001), and a decline in CH₄ yield of 21% (25.6–20.2 g/kg DM intake; P<0.001). High feed intake levels were associated with increased molar proportions (mM of total VFA) of propionate from 0.17 to 0.21 (P=0.038). Single and multiple regressions were completed on the data from all experiments, with organic matter (OM) intake predicting 0.87 of the variation in CH₄ production, and molar proportion of propionate predicting 0.60 of the variation in CH₄ yield. Increasing feed intakes by 1 kg/d of DM reduced CH₄ yield by 4.5 g/kg DM intake. Plant chemical composition was weakly related to CH₄ yield. High intakes of fresh forages will lower CH₄ yield from fermentation, but effects of feed composition on CH₄ emissions were minor. The interaction between effects of feed intake and rumen function requires further investigation to understand relationships with CH₄ emissions.     

Long-day photoperiod exposure in lactating goats to induce post-partum ovulatory activity

In the present study, the continuous application of an artificial long-day photoperiod to induce a refractory state affecting the recovery of post-partum ovulatory activity in subtropical Creole does kidding in autumn, was investigated. For this purpose, a group of does was kept under a natural photoperiod from parturition up to 158 days of lactation (control group: n = 16). The other group was subjected to an artificial long-day photoperiod (16 h light:8 h darkness; treated group: n = 16) from day 10 to 158 of lactation. For the first 96 days postpartum, all does from both the control and treatment groups did not show ovulation. However, from day 108 to 156 post-partum, the proportion of does that exhibited ovulation was greater (P < 0.01) in the treated group (11/16; 69%), than in the control group (2/16; 12.5%). In addition, the does in the treated group produced 15% more milk on average than the does in the control group at 60 and 90 days of lactation (P < 0.001). The body weight and body condition were not affected by the photoperiod treatment (P > 0.05). It could be concluded that, for subtropical lactating does that gave birth in autumn, continuous exposure to an artificial long-day photoperiod induces post-partum ovulatory activity after 150 days of exposure. This behaviour is probably attributable to the induction of a refractory state of the ovary, following continuous exposure to the artificial long days. Furthermore, this photoperiod treatment also increased the milk production level in goats at 60 and 90 days of lactation.     

Beef cattle pasture to wetland reconversion: Impact on soil organic carbon and phosphorus dynamics

There is a major need to understand the historical condition and chemical/biological functions of the ecosystems following a conversion of wetlands to agricultural functions. To better understand the dynamics of soil total organic carbon (TOC) and phosphorus (P) during beef cattle pastures to wetland reconversion, soil core samples were collected from the beef cattle pasture and from the natural wetland at Plant City, FL, during five summer seasons (2002–2007). The levels of TOC and soil P were significantly affected by changing land use and hydrology. Draining natural wetlands to grazed pastures resulted in very pronounced reduction of TOC from 180.1 to 5.4 g g^?1. Cumulative concentrations of total phosphorus (TP) in soils (1134 mg kg^?1) under drained condition are two to three times lower than those in soils (2752 mg kg^?1) under flooded condition over the periods of land use reconversion. There was a declining trend (r = 0.82**; p ≤ 0.01) in total soil P from natural wetland (763 mg kg^?1) to altered pastures (340 mg kg^?1), largely as organic-bound P (natural wetland, 48%; grazed pastures, 44%; altered pastures, 29%). These results are important in establishing baseline information on soil properties in pasture and wetland prior to restoring and reconverting pasture back to wetland conditions. The results further suggest that changes in soil properties due to changing land use and hydrologic conditions (drying and re-wetting) could be long lasting.     

Diet selection and eating behaviour of lactating goats subjected to time restricted feeding in choice and single feeding system

This study was carried out to investigate diet selection and eating behaviour of lactating German Fawn × Hair Crossbred goats in different feeding methods and levels. Twenty German Fawn × Hair first backcross does (B₁) were allocated into 4 treatment groups (2 feeding methods single (TMR) and choice feeding × 2 feeding levels ad libitum and restricted) with 5 replicates. Restricted feeding was applied only 4 h feed allocation during day. Barley, corn, soybean meal, corn gluten meal, wheat bran and alfalfa hay were feed ingredients for single and choice feeding. Eating patterns, milk yield and composition were determined for 8 weeks. The following results were obtained: (1) the meal criteria for goats restricted single and choice-fed, ad libitum single and choice-fed were determined as 1.00 and 0.63, 12.88 and 10.23 min, respectively. (2) Ad libitum feeding increased meal size, meal length, intermeal interval, total eating duration and decreased eating rate and meal number, compared to restricted feeding (P < 0.01). Choice feeding decreased meal size (P < 0.05), meal length (P < 0.01) and increased eating rate and meal number (P < 0.01), compared to single feeding. Restricted fed goats decreased intermeal interval in single feeding compared to choice feeding (P < 0.01), but increased meal number in choice feeding (P < 0.01). (3) Ad libitum choice-fed does made a diet containing 12.79% corn, 35.41% barley, 13.21% wheat bran, 5.35% soybean meal, 1.28% corn gluten meal and 29.80% alfalfa meal while restricted choice-fed does made a diet having more corn (27.69%), corn gluten meal (5.62%) and wheat bran (16.17%) and less barley (14.37%) and soybean meal (4.51%). (4) Choice feeding decreased RUP intake (P < 0.05) without affecting milk protein, irrespective to feeding levels, while having a tendency to increase in milk yield (14.2%) and 4% FCM (8.8%). (5) Restricted feeding decreased DM, ME, ADF and NDF intakes (P < 0.05) with concomitant decreases in 4% FCM, total milk solid, ash and fat compositions (P < 0.05), irrespective to feeding methods. (6) Choice-fed goats changed their preferences for a possible synchronized nutrient intake during a daytime, as sorted barley, soybean meal and alfalfa hay from early morning to late afternoon.It could be concluded that choice-fed goats have the ability to make their diet to meet nutrient requirements and had a tendency to increase in milk yield. Restriction in feeding time resulted in lower feed intake and milk yield, although the animal changed their feed preference in favour of high quality ingredients and eating pattern with lower meal criterion and intermeal interval.     

Effect of administration of live Saccharomyces cerevisiae on milk production,milk composition,blood metabolites,and faecal flora in early lactating dairy goats

The effects of live Saccharomyces cerevisiae (CNCM I-1077) supplementation to 72 Saanen dairy goats in early lactation were investigated. Animals were divided into treatment and control groups balanced for parity and milk production in the first 3 weeks of lactation. Treated animals received 0.2 g/day yeast supplement (Levucell SC20) corresponding to 4 × 10⁹ cfu/day S. cerevisiae, beginning week 3 of lactation, and lasting 15 weeks. Dry matter intake (DMI), body condition score (BCS), milk production and composition were recorded to day126 postpartum. Milk samples were analysed weekly for fat, protein, lactose, urea and SCC. Blood samples were analysed monthly for glucose, BHBA, NEFA, GOT and GGT. Intestinal microflora were assessed monthly in faeces, assaying total bacteria, enterobacteria, E. coli, coliform bacteria, clostridia, lactobacilli, molds and yeast. BCS was not affected by the treatment, but treated animals had greater DMI (2.71 kg/day versus 2.35 kg/day, S.E. ±0.12, P < 0.001) and produced more (P < 0.05) milk (2.38 kg/day versus 2.08 kg/day, S.E. ±0.14) of lower fat content (P < 0.05). Plasma metabolites and liver enzymes (GOT, GGT) were similar between groups, although BHBA levels tended to be lower (P = 0.06) in treated animals. Faecal E. coli were reduced (0.72 log₁₀ cfu/g versus 2.39 log₁₀ cfu/g, S.E. ±0.38, P < 0.05) and lactobacilli increased (P < 0.05) by the treatment. Yeast faecal levels were higher (P < 0.001) in treated animals during supplementation. In this study, live yeast supplementation to early lactating dairy goats significantly increased milk production, in relation to increased DMI, without decreasing BCS. Plasma metabolites (glucose, BHBA and NEFA) were consistent with the BCS findings (no differences between groups) and in addition there was a significant reduction of faecal E. coli content together with increase in lactobacilli in the treated animals, suggesting greater stability of the intestinal ecosystem. Results suggest that the inclusion of Saccharomyces cerevisae in the diet of early lactating dairy goats can be recommended under field conditions.     

The ovulatory and LH responses to the male effect in dominant and subordinate goats

The objective of this study was to evaluate the LH and ovulatory response of dominant and subordinate dairy does following the introduction of males. A behavioral study was carried out to determine the individual success index (SI) of 35 anestrous does according to their ability to dominate other females. The 8 highest-ranking (highest SI) and the 8 lowest-ranking does (lowest SI) in terms of dominance were separated from the rest of the herd and placed together in the same pen, where a male was later introduced. Blood samples for plasma LH determinations were obtained from the 16 females at 30 min intervals from 0 to 6, 12 to 18 and 33 to 39 h after the introduction of the male, using an intravenous catheter. After day 8, plasma progesterone was also measured daily in order to determine the occurrence of ovulation. None of the does showed LH pulses during the sampling period prior to the introduction of the male. The dominant does showed significantly (p < 0.05) more LH pulses (2.0 ± 0.18 ng/ml vs. 1.2 ± 0.25 ng/ml) and a higher mean plasma LH concentration (0.25 ± 0.03 ng/ml vs. 0.14 ± 0.03 ng/ml) than the subordinate goats during the first 6 h of exposure to the male. There were no differences in LH pulsatility or concentrations at other times. The frequency of goats that ovulated tended to be greater in high-ranked than low-ranked does (87% vs. 37%). It could be concluded that the immediate LH response to the presence of the male (number of LH pulses) is higher in the dominant, compared to the subordinate goats, and this is associated with a higher number of dominant goats ovulating in response to the male effect.     

Efficiency of energy use for pregnancy by meat goat does with different litter size

Twenty-four Boer × Spanish does (3 years of age, having kidded once previously and with an initial BW of 42.7 ± 1.2 kg) were used to determine the efficiency of ME utilization for pregnancy (k_preg). Six does were nonpregnant and, based on ultrasound determination on day 45 of gestation, six had a litter size (LS) of 1, 2, and 3. However, only 10 of the pregnant does delivered the expected number of kids (3, 4, and 3 with LS of 1, 2, and 3, respectively). Does were fed a diet of approximately 50% concentrate in accordance with assumed maintenance plus pregnancy energy requirements based on estimated nonpregnancy tissue BW and LS. Recovered energy (RE) was determined by subtraction of energy expenditure (EE; respiration calorimetry) near days 80, 100, 120, and 140 of gestation from ME intake (MEI). RE was assumed attributable to pregnancy tissues (fetus, fetal fluids and membranes, uterus, and mammary gland), and ME used for pregnancy (ME_preg) was estimated by subtracting ME_m determined with nonpregnant goats from MEI by those pregnant. For does with actual LS equal to that expected, the no-intercept equation for the regression of RE against ME_preg was: RE = ME_preg × 0.252 (S.E. = 0.030; R² = 0.64), indicating a k_preg of 25%. A regression including LS (1 versus 2 or 3) suggested greater k_preg for LS of 1 (40.2 ± 5.6%) versus 2 or 3 (20.5 ± 3.2%). Regressions for goats with LS different from expected suggested positive effects of use of energy mobilized from nonpregnancy tissues on k_preg and of use of dietary ME for energy accretion in nonpregnancy tissues on the efficiency of whole body ME utilization. In conclusion, the average efficiency of ME use for pregnancy regardless of LS in goats was near 25%, which when considering the expected proportion of all pregnancy tissues attributable to fetal or conceptus tissues implies an energy requirement for pregnancy of goats similar to common recommendations for sheep and cattle.     

Effect of artificial vs. natural rearing on milk yield,kid growth and cost in Payoya autochthonous dairy goats

Seventy full lactations of Payoya dairy goats were used to study the effect of two different kid-rearing systems, natural or artificial, on milk yield, composition, hygiene-sanitary quality, kid growth and rearing cost. Two animal groups were established, one with goats under natural rearing (NS) and the other under artificial rearing (AR). In the NS group, the kids had free access to goat milk 18–20 h a day and were suckled up to 5 weeks of age and then the dams were milked twice daily. Dams in the AR were separated from their kids at 48 h post-partum; then, kids were reared artificially, and the dams were milked twice daily. The number of animals used in each type of rearing system was 35 (23 goats giving birth to twins and 12 goats giving birth to a single kid). Each week during suckling phase the volume of milk produced was measured, and individual samples were taken. From 5th week and until 210 days lactation, test-day yields recorded at intervals of 30 ± 3 days were obtained. The chemical composition of the milk, the bacteriology, and the somatic cell count was analyzed. The kids of both sexes were assigned to two groups, natural suckling (NS, n = 58) and ad libitum artificial rearing (AR, n = 58). Within each treatment, two groups of kids were formed depending on prolificacy: first group with kids from single birth (n = 12) and the second with twin kids (n = 46). Birth weight and weight every week upto the 4th week of life were recorded. During the 5 weeks of lactation the total milk yield per goat was higher for the NS group (140.2 L vs. 95.4 L; P < 0.001), although the total amount of marketable milk was greater for the AR group, with a difference of some 21 L (P < 0.05). Throughout the entire lactation the milk yield was higher in the group of natural rearing (total yield of 508 L vs. 400 L; P < 0.05). Although a significant effect of prolificacy was found during suckling phase (P < 0.001), during 30 weeks of lactation this factor did not affect milk yield (P > 0.05). For the milk composition and hygiene-sanitary quality there were no effects on the type of rearing system or the type of birth (P > 0.05). No significant effect was observed either for the feeding system or the sex or the prolificacy on the live weight of the kids at 28 days and the postnatal growth rate from birth to 28 days (P > 0.05). Natural rearing system had higher cost per kid comparing with artificial rearing system (€18.63/kid vs. €14.70/kid, respectively). However, when comparing total incomes during a full lactation, goats with natural rearing system had a higher income because of increment of total milk production (€29.95/kid).