Lamb Weaning Research Articles

A preliminary study of the effects of organic farming on oocyte quality in ewe lambs

This study tested whether feeding Rasa Aragonesa ewes certified organic feed, from 15 days before mating until lamb weaning, improved oocyte quality and in vitro maturation (IVM) and fertilization (IVF) performances of the offspring. In a second experiment, ovaries from ewe lambs that were bred on an organic farm and were of the same breed were compared with those from conventionally bred animals. The number (± standard error of the mean) of healthy oocytes per ewe lamb did not differ significantly between organic (12.2 ± 3.3) and conventionally (13.6 ± 4.0) fed ewes. Ovaries from ewe lambs born on an organic farm had significantly (P < 0.0001) more healthy oocytes per ewe lamb (39.6 ± 5.2) than did those born on a conventional farm (25.0 ± 4.2), and higher IVM (76.5% vs. 53.1%, P < 0.0001) and IVF (97.3 vs. 91%, P < 0.05) rates. In conclusion, this preliminary approach to the study of the effect of organic procedures on the sheep oocyte quality indicates that the total integration in the complete organic system improved the oocyte quality of ewe lambs, although organic feeding alone was insufficient to improve quality.

Comparison of two long acting pre-lambing anthelmintic treatments on the productivity of ewes in low body condition

AIM: To determine if there was a benefit from treating ewes with a low body condition score (BCS) with long acting anthelmintic products pre-lambing and to compare the effects of two commonly used treatment options.METHODS: The study was conducted on a single commercial hill country sheep and beef property in the central North Island of New Zealand. Mixed age twin-bearing ewes were preselected by the farmer as being in poor condition 4 weeks before the planned start of lambing, and were sequentially drafted into three equal groups identified with coloured ear tags. The negative control group (n=199) received no anthelmintic treatment; the other two groups received either a controlled release capsule (CRC) containing abamectin, albendazole, Se and Co (n=200) or a long-acting injection of moxidectin (n=200). All ewes were body condition scored (1–5 scale) and weighed at pre-lambing, docking (65 days after treatment) and at weaning (127 days after treatment). Faecal nematode egg counts (FEC) were carried out on 10 ewes from each group at these three times. Most lambs were matched to the ewe treatment groups at weaning, and weighed.RESULTS: At weaning the mean body weight of ewes treated with moxidectin was 3.2 (95% CI=2.3–4.3) kg heavier than controls, and of ewes treated with CRC was 3.6 (95% CI=2.5–4.5) kg heavier than control ewes (p<0.001). At the start of the trial only 61/599 (10.2%) ewes had a BCS≥3. At weaning, more ewes treated with CRC (140/194; 72%) or moxidectin (122/187; 65%) had a BCS≥3 than control ewes (55/179 (31%); p<0.001). In lambs that were matched with ewes from the treatment groups, the mean weight at weaning of lambs from ewes treated with moxidectin was 2.6 (95% CI=1.9–3.3) kg heavier, and from ewes treated with CRC was 2.6 (95% CI=1.9–3.4) kg heavier than lambs from control ewes (p<0.001).CONCLUSIONS AND CLINICAL RELEVANCE: Treating twin-bearing ewes with low BCS pre-lambing with long acting anthelmintic treatments (moxidectin long acting injection or CRC) resulted in an increase in mean body weight of the ewes and lambs at weaning. There were no significant differences between the two pre-lambing treatments used. These results were based on a single property and thus cannot be generalised to all properties where management conditions and parasite populations may differ.

Meat quality, organoleptic characteristics and fatty acid composition of Dorset lambs fed different forage to concentrate ratio or fresh grass

A total of forty 24 kg male Dorset weaning lambs were allocated in four dietary treatment groups: ad libitum concentrates (C), restricted concentrates (RC), zero grazing (ZGR), and grazing (GR). La...

Impact of body condition on postpartum features in morada nova sheep

This study evaluated the impact of nutritional status of Morada Nova sheep at lambing on the reproductive and productive performance and on the survival of lambs in early weaning system. Nineteen, Morada Nova sheep were assigned to two groups according to body condition score (BCS) at lambing: low BCS (n = 11) and high BCS (n=8) with body condition respectively of (mean ± SD) 2.0 ± 0.3 e 2.9 ± 0.1. From birth until lamb weaning (45 days), sheep were weighed weekly and checked the BCS, loin subcutaneous fat thickness, loin depth, hematological profile, milk composition and production, and every three days, we measured the uterine diameter. Lamb weightings were performed up to one week after weaning (52 days). The lower availability of muscle and fat reserves in the low BCS group negatively affected milk production and consequently performance of suckling lambs. However, the results indicated that the uterine involution process, the reproductive parameters including prolificacy, rate of multiple births, number of white blood cells, milk quality, body weight of lambs at birth and mortality rates were not affected by the body condition. The results allowed to describe the responsiveness to opposite nutritional status of Morada Nova sheep, showing their characteristics of adaptation.

Hypothalamic-pituitary GnRH/LH axis activity is affected by salsolinol in sheep during lactation: Effects of intracerebroventricular infusions of salsolinol and its antagonizing analogue

The aim of the study was to test the hypothesis that salsolinol, a derivative of dopamine, is involved in the regulation of hypothalamic-pituitary gonadotropic (GnRH/LH) axis activity in lactating sheep. In the first experiment performed on sheep during the fifth week of lactation, a structural analogue of salsolinol (1-MeDIQ) was infused into the third brain ventricle (IIIv) to antagonize its action within the central nervous system (CNS). A push–pull perfusion of the infundibular nucleus/median eminence was performed simultaneously, and blood samples were collected from the jugular vein. In the second experiment, sheep received infusions of salsolinol into the IIIv, 48 hours after the weaning of their 8-week-old lambs. Blood samples were collected during the experimental periods, and the anterior pituitary (AP) tissue was dissected immediately after the end of the experiment. Perfusate GnRH concentration (experiment 1), plasma LH concentration (experiments 1 and 2), and relative LHβ mRNA levels in the AP tissue (experiment 2) were assayed. Blocking of salsolinol action in the CNS of lactating sheep caused a significant (P < 0.001) decrease in the perfusate GnRH concentrations in comparison with controls. Treatment with 1-MEDIQ also significantly decreased (P < 0.001) the LH concentration in the blood plasma. In turn, salsolinol infused 48 hours after lamb weaning significantly (P < 0.001) increased plasma LH concentration, reflected in the significant (P < 0.05) increase in the amplitude of LH pulses in the treated sheep as compared to the control animals. There was no significant difference in the relative levels of LHβ-subunit mRNA in the AP between control and salsolinol-infused sheep. The results lead to a conclusion that salsolinol affects the secretory activity of the GnRH/LH axis in sheep during lactation. Whether salsolinol infused into the IIIv evokes this stimulatory effect by itself or by modulation of other regulatory systems needs to be clarified.

Growth performance and rumen microorganism differ between segregated weaning lambs and grazing lambs

Two feeding patterns of the segregated weaning or grazing in the pasture are carried out worldwide in animal production. To investigate the difference of growth performance and rumen microorganism population related to methane metabolism in the two feeding patterns, three groups of lambs (70 in total) were used: Weaning at 21 days old and being subjected to high-concentration diets (3WK group with 20 lambs), weaning at 35 days old and being subjected to high-concentration diets (5WK group with 20 lambs), or grazing at pasture with the nursing mother (Grazing group with 30 lambs). The growth performance, pH value of rumen content, and the rumen microbes were investigated during weaning period and fattening period with approximately 3 months. Our results showed that lambs in 3WK and 5WK groups demonstrated a better growth performance than the lambs in Grazing group, but no significant difference was observed in the pH value between the three groups (P>0.05). The total rumen bacterial population of the Grazing lambs was significantly lower than that of 3WK lambs (P<0.05) and 5WK lambs (P<0.05); however, the population of methanogens was 4.2- and 2.7-fold lower in the 3WK (P<0.05) and 5WK (P<0.05) lambs compared with Grazing lambs, respectively; protozoa were also 3.5- and 3.4-fold lower in the 3WK (P<0.05) and 5WK (P<0.05) lambs, respectively. The results revealed that segregated weaning lambs may have better growth performance, and reduce methane-producing microbes.

Increasing lamb survival and lamb weaning weight through feeding high fecundity crossbred sheep

The monitoring of a high fecundity ewe flock in the Te Anau basin demonstrates the process of improved feeding to improve lamb survival and growth to weaning. Feed budgeting was changed from traditional to tailored feed requirements based on measured ewe liveweight with wastage of 15% factored in. Feed allocation was changed from monthly to weekly increases during late pregnancy, and set stocking was delayed until the planned start of lambing. This increased late pregnancy feed allocation from 99 kg DM/ewe to 128 and 144 kg DM/ewe for twin and triplet bearing ewes, respectively. Ewe body condition score was maintained at between 3 and 3.5, with condition score loss between scanning and lambing being reduced to zero. Lamb survival and lamb liveweight gain to weaning increased in both twin and triplet bearing ewes. Pregnancy scanning increased from 200 to 222 lambs per 100 ewes, between 2007 and 2012, while lambing percentage (lambs weaned/ ewe mated) rose from 132% to 165%, with more ewes rearing lambs and rearing multiples. Lamb wastage declined from 37% in 2007 and 2008, to 25% in 2011 and 2012, though scanning percentage rose by 20%. Lamb weights increased from 27.5 to 36 kg/lamb at 100 days of age. The increase in the liveweight of lambs and ewes at weaning reduced the calculated feed requirements over summer and autumn, potentially releasing 70 to 110 kg DM/ewe to provide feed to meet the extra winter feed requirements. Keywords: ewe body condition score, feed allocation, lamb survival, lamb weaning weight

Effects of suckling duration on growth, slaughtering and carcass quality characteristics of Kivircik lambs.

Effects of suckling length (45, 75 and 120days) and birth type (single and twin) on lamb growth, slaughtering and carcass quality characteristics were investigated using 40 Kivircik lambs. SC-45 and SC-75 lambs were weaned at 45 and 75days of age, respectively, whilst SC-120 lambs remained with their mothers until the end of the experimental period. Lambs from all studied groups were slaughtered at 120days of age. Weaning treatment caused a decrease in average daily gain in SC-45 and SC-75 lambs, and therefore, final weight was higher in SC-120 lambs than lambs from weaned groups. SC-120 lambs had higher empty body weight, cold carcass weight, dressing percentage, carcass measurements, carcass fatness (proportions of the kidney knob and channel fat, subcutaneous and intramuscular fat in pelvic limb) and non-carcass fatness (omental and mesenteric fat proportion) than weaned lambs. As a conclusion, the potential losses in meat production due to weaning should be considered before deciding the weaning of lambs at early ages.

Accidental and experimental Closantel intoxication in Uruguayan sheep

Abstract An outbreak of Closantel intoxication in sheep in Uruguay is described. The outbreak occurred in a group of 1300 weaning lambs treated orally with a 10% solution of Closantel. One hundred forty eight lambs showed clinical signs of intoxication and 14 died. The clinical signs included mydriasis, nystagmus, and negative pupillary reflex, bilateral blindness, bump into objects, and lateral movement of the head. No macroscopic lesions were observed. The histological lesions of the retina were cytoplasmic vacuolization in ganglion cells and in cells of the inner and outer nuclear layers with different degrees of atrophy. Vacuolization and axonal degeneration were observed in the optic nerve, with multifocal areas of fibrosis and infiltration by lymphocytes and Gitter cells. To reproduce the intoxication, four sheep were given two, four and 10 times the therapeutic dose of Closantel (0.1g/kg of BW). Only the animals receiving 10 times the recommended dose showed clinical signs. The histological examination of the lesions in experimental sheep showed similar results to those described in the accidental outbreak, except for the absence of optic nerve fibrosis and inflammation, characterizing an acute phase. Axonal myelin sheaths loss, fibroblasts and collagen fibers were observed in the ultrastructural study of the optic nerve of accidental intoxicated animals. The optic nerve of experimentally intoxicated animals had vacuoles that separated the myelin sheaths of axons. To prevent outbreaks it is suggested to weigh the animals before Closantel administration to avoid errors in dose calculation.

Salsolinol: a potential modulator of the activity of the hypothalamic–pituitary–adrenal axis in nursing and postweaning sheep

The most well-known physiological action of salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is the stimulation of prolactin secretion, especially during lactation. In addition, our recent work demonstrated that salsolinol inhibits the stress-induced activity of the hypothalamic–pituitary–adrenal (HPA) axis in lactating sheep. Here, we investigated whether salsolinol regulates the basal activity of the HPA axis in lactating sheep and whether its inhibitory action on the stress-induced activity of the HPA axis is present during the postweaning period. The first experiment was performed during the fifth week of lactation, in which unstressed sheep received an intracerebroventricular infusion of an antagonistic analogue of salsolinol, 1-MeDIQ (1-methyl-3,4-dihydroisoquinoline). Simultaneously, the infundibular nucleus and/or median eminence was perfused using the push–pull method. Sheep that received 1-MeDIQ infusion showed significantly higher concentration of plasma ACTH during the second, third, and fourth hour (P < 0.001, P < 0.01, and P < 0.001, respectively) and cortisol during the third and fourth hour (P < 0.001 and P < 0.01, respectively) than did sheep that received control infusion. There was no significant difference in the mean perfusate corticotropin-releasing hormone concentration between the 1-MeDIQ and control treatments. In the second experiment, sheep received an intracerebroventricular infusion of salsolinol during the ninth week of lactation and 48 h after lamb weaning. A comparison between the control groups in the first and second experiments revealed that sheep after weaning (ninth week of lactation) had significantly higher mean ACTH (P < 0.001) and cortisol (P < 0.001) concentrations during the first 2 h of the experiment than the nursing females (fifth week of lactation) had. Salsolinol significantly reduced the increased concentrations of ACTH and cortisol (P < 0.01) in sheep after lamb weaning. However, there was no difference in the expression of proopiomelanocortin messenger RNA within the anterior pituitary between the control and salsolinol-treated groups. In conclusion, salsolinol regulates the basal activity of the HPA axis in lactating sheep. In addition, the HPA axis of postweaning females is more sensitive to stressors associated with the experimental procedures, and salsolinol attenuates ACTH and cortisol release in this phenomenon.

Blood Malondialdehyde, Reproductive, and Lactation Performances of Ewes Fed High PUFA Rations Supplemented with Different Antioxidant Sources

The aims of this study were to evaluate the effect of vitamin E (vit E) and black tea extract (BTE) as antioxidant sources in high poly-unsaturated fatty acid (PUFA) rations on blood malondialdehyde (MDA) concentrations and the performance of reproduction and lactation of Garut ewes. Twelve ewes on late pregnancy periods were divided into completely randomized design (CRD) with 3 treatments and 4 replicates. The treatments were control: basal diet without antioxidant, vit E: basal diet supplemented with vit E, and BTE: basal diet supplemented with BTE. The results showed that vit E and BTE supplementation did not affect blood MDA concentration of ewes on late pregnancy, lactation periods, and weaning periods. Antioxidant sources supplementation had no effect on ewe’s nutrient intake, pre-lambing live weight change (LWC), and post-lambing average daily gain (ADG). Vit E supplementation had decreased the milk production, but both of antioxidant sources give positive effect on the milk composition. Nevertheless, the supplementation of vit E and BTE increased the twin type of birth. The vit E supplementation resulted higher lambing rate than BTE, although it had the highest mortality rate of twin lamb. BTE also had better lamb weaning weight than vit E. BTE and vit E gave similar results in ewes productivity on lactation period. In conclusion, this study confirmed that BTE was more effective used as antioxidant source than vit E to prevent the oxidative reaction of PUFA. Vit E supplementation on high PUFA ration reduced ewes milk production but it had similar reproduction performance with BTE. Key words: antioxidant, black tea extract, ewes, lactation, reproduction, vitamin E

OCORRÊNCIA DE MASTITE SUBCLÍNICA OVINA DURANTE DUAS LACTAÇÕES CONSECUTIVAS EM REBANHO DA RAÇA SANTA INÊS

O objetivo desse estudo foi avaliar a ocorrência da mastite subclínica ovina em duas lactações e a evolução da doença em duas lactações consecutivas. As amostras de leite foram originadas de um rebanho com 160 ovelhas da raça Santa Inês. Na primeira lactação, colheram-se amostras em ovelhas aos 14 dias pós-parto e no período próximo ao desmame. Na segunda lactação, as amostras de leite foram colhidas dos mesmos animais aos 14 dias pós-parto, 52 dias pós-parto e ao desmame. A triagem dos casos de mastite subclínica foi feita preliminarmente por meio do California Mastitis Test (CMT). As amostras de leite para a investigação microbiológica foram obtidas de metades mamárias positivas e negativas ao CMT. Os estafilococos coagulase-negativos foram os micro-organismos de maior ocorrência nas duas lactações. Houve a predominância de ovelhas que permaneceram com mastite subclínica durante a Lactação 1. As curas espontâneas foram significativamente inferiores no período entre 52 dias de lactação e o desmame dos cordeiros. Nenhuma diferença foi observada quanto à evolução dos casos de mastite subclínica infecciosa quando comparadas duas lactações (P&gt;0,05).

A partial suckling regime increases milk production in Sarda dairy sheep without affecting meat quality of lambs

The collection of milk from dairy sheep has to be balanced with the need for the sheep to feed their lambs at the start of their lives. In Sardinia the sheep nurse their lambs for the first 30 days of their lives when the lambs are slaughtered to produce the traditional PGI (Protected Geographical Indication) Sardinian lamb. In this study the traditional Total Suckling (TS) system was compared with a Partial Suckling (PS) method in which the sheep were separated from the lambs during the day, milked in the evening, and then were allowed to nurse the lambs overnight. Since the removal of milk enhances milk production, a larger milk yield in the TS group was expected compared to the PS group. The production and composition of the milk were measured during the suckling period and for four weeks after lamb weaning. The growth rates of the lambs and the characteristics of their carcasses were measured after slaughter and an economic evaluation of the milk production to compare the two systems was conducted. Sheep in the Partial Suckling group produced 562g of milk/day more than the sheep in the TS group during the suckling period and 168g/day more milk than the sheep in the PS group after the lambs were slaughtered. This resulted in extra returns of about 10€/ewe compared to the traditional TS technique. Although the milk fat concentration was lower in the milk of the PS sheep during the nursing period (4.6% vs. 6.3%; P<0.01) this rose to 5.4% as soon as the lambs were slaughtered and was not different from that of the TS group (5.6%; P>0.05). There were no significant differences in the characteristics of the carcasses of the two groups of lambs, with the exception of the cold dressing percentage, which was significantly lower in carcasses from the PS group (60% vs. 65.5%; P<0.05). It can be therefore concluded that PS allows harvesting more milk than the TS traditionally adopted by Sardinian shepherds thus resulting in greater returns from the sale of milk. In addition, this rearing system did not affect the production and quality of meat from the lambs.

Supplementing metabolizable protein to ewes during late gestation: II. Effects on ewe lamb performance and reproductive efficiency.

The objective of the current study was to determine the effects of maternal MP intake in isocaloric diets during late gestation on female offspring growth from birth to breeding and measure reproductive performance of those offspring in their first breeding season. In yr 1, maternal dietary treatments were applied at d 100 of gestation, were similar in total energy, and contained 60MP1, 60% of MP requirements; 80MP1, 80% of MP requirements; and 100MP1, 100% of the MP requirements on a DM basis during late gestation. In yr 2, maternal dietary treatments were similar in total energy and contained 60MP2, 60% of MP requirements; 100MP2, 100% of the MP requirements; and 140MP2, 140% of MP requirements on a DM basis during late gestation. While there was a quadratic effect ( = 0.003) for ewe lamb birth weight with the ewe lambs from 80MP1 ewes having increased birth weights compared with ewe lambs from 60MP1 and 100MP1 ewes in yr 1, there was no effect ( ≥ 0.22) of maternal diet on growth of ewe lamb offspring thereafter. A quadratic effect ( = 0.02) was observed for the percentage of ewe lambs bred during the first 17 d of the breeding season, with more ewe lambs born to ewes fed 80MP1 bred compared with ewe lambs born to ewes fed 60MP1 and 100MP1. Ewe lambs giving birth within the first 17 d of lambing season increased ( = 0.001) linearly as MP intake increased in the maternal diet. In yr 2, there was no effect ( ≥ 0.07) of maternal MP treatment during late gestation on growth of ewe lambs and reproductive performance except ADG from birth to weaning and lamb birth weight. There was a quadratic effect ( = 0.01) for ADG from birth to weaning of ewe lambs from ewes consuming 100MP2 being increased compared with ewe lambs from ewes fed 60MP2 and 140MP2. There was a linear ( = 0.04) reduction in birth weight of lambs born to ewe lambs as the dam's maternal dietary MP intake increased. The data from the current study suggest that feeding 80% or 100% of MP requirements during late gestation may have the greatest positive impacts on female offspring reproductive performance.

Potential impacts of different spring grazing strategies on lamb finishing in hill country

How does the pasture cover at the beginning of lambing and the grazing strategy used in early spring influence the ability of a hill country sheep and beef farm to finish lambs? The results from an intensive pasture-mowing trial investigating three defoliation intensities (Lax, Moderate and Intense) starting from two herbage masses (1200 or 1500 kg DM/ha) during early spring were used to provide data on potential pasture consumption and feed quality from lambing to weaning for a breeding ewe flock. Using simulation modelling, this pasture data was used to estimate the potential lamb and ewe liveweight changes from birth to weaning at each of three different stocking rates (4.5, 8 and 10.5 twin-bearing ewes/ha) that closely represented the three defoliation intensities originally studied in a mowing trial. The impacts of these early-spring herbage masses and grazing intensities/ stocking rates on subsequent feed requirements and potential lamb finishing during the later summer and autumn period in four contrasting geo-climatic regions of New Zealand were then further investigated using simulation modelling. Variations in ewe and lamb weaning weights were evident and reflected the amount of pasture available through the different grazing management approaches. For all four geoclimatic regions studied, the Intense grazing, high stocking rate strategy generally produced the greatest gross revenue per ha from lamb sales out of the three grazing strategies investigated, though not significantly greater than the moderate stocking rate in summer dry environments. However, under Intense grazing, a high pasture cover (1500 kg DM/ha), in comparison to a low pasture cover (1200 kg DM/ha) at the start of ewe lactation further improved the gross revenue received from lamb sales, especially in the Canterbury and Waikato environments but less so in the Hawke's Bay and Southland environments. These variations demonstrate how iterations based on the same starting properties impact on weaning weight of lambs and post-weaning pasture growth and/or feed quality. Keywords: emergence, feed supply, geo-climatic regions, iteration, lactation, lamb weaning weight, pasture quality.

Partial suckling of lambs reduced the linoleic and conjugated linoleic acid contents of marketable milk in Chios ewes

The objective of this work was to investigate the effect of weaning systems applied in a commercial dairy sheep farm on the fatty acid (FA) composition of marketable milk produced. Forty second parity, purebred Chios ewes were allocated to the following weaning treatments: (a) ewes were weaned from their lambs at 48h after birth and machine milked twice daily [no lambs (NL) group, n=20]; or, (b) starting 48h postpartum, ewes were separated from their lambs for 12h during the evening, machine milked once daily the following morning, and lambs were allowed to suckle for 12h during the day for the first 5wk of lactation [partial suckling (PS) group, n=20]. After weaning of the PS lambs at wk 6 of age, all ewes were machine milked twice daily. Commercial milk yield and milk composition was recorded weekly (fat, protein, FA content) or fortnightly (somatic cell counts) throughout the first 10wk of lactation. The PS ewes compared with NL group produced commercial milk lower in milk yield, milk fat, and somatic cell counts, but not in protein content during the first 5-wk period. Such differences were not observed after weaning of the PS lambs. The FA profile of commercial milk was also affected by partial suckling during the preweaning period. Total polyunsaturated FA were higher in NL compared with PS ewe milk at wk 1, 2, 4, and 5 (on average, 21% higher), whereas no differences were detected between NL and PS ewe milk from wk 6 to 10 of lactation. From the polyunsaturated FA, linoleic acid (C18:2 cis-9,cis-12) and conjugated linoleic acid (C18:2 cis-9,trans-11; rumenic acid) were particularly affected, showing on average a reduction of 18 and 38%, respectively. From the monounsaturated FA, vaccenic acid (C18:1 trans-11) was affected during wk 1 and 2 of the treatment period, with the PS ewe milk having reduced content compared with the NL milk. Other unsaturated FA, such as oleic acid and α-linolenic acid, or saturated FA were not found to be affected by the weaning treatment. The results indicate that partial suckling of lambs during the first 5wk of lactation adversely affected both the total fat content of milk obtained by machine milking of their dams and the unsaturation content of the milk fat. Particularly affected were the linoleic acid and cis-9,trans-11 conjugated linoleic acid content of ewe milk.

Body condition score as a selection tool for targeted selective treatment-based nematode control strategies in Merino ewes

Sheep nematode control utilising refugia-based strategies have been shown to delay anthelmintic resistance, but the optimal indices to select individuals to be left untreated under extensive sheep grazing conditions are not clear. This experiment tested the hypothesis that high body condition can indicate ability of mature sheep to better cope with worms and therefore remain untreated in a targeted treatment programme. Adult Merino ewes from flocks on two private farms located in south-west Western Australia (Farm A, n=271, and Farm B, n=258) were measured for body condition score (BCS), body weight and worm egg counts (WEC) on four occasions between May and December (pre-lambing, lamb marking, lamb weaning and post-weaning). Half of the ewes in each flock received anthelmintic treatments to suppress WEC over the experimental period and half remained untreated (unless critical limits were reached). Response to treatment was analysed in terms of BCS change and percentage live weight change. No effect of high or low initial WEC groups was shown for BCS response, and liveweight responses were inconsistent. A relatively greater BCS response to treatment was observed in ewes in low BCS pre-lambing compared to better-conditioned ewes on one farm where nutrition was sub-optimal and worm burdens were high. Sheep in low body condition pre-lambing were more than three times more likely to fall into a critically low BCS (<2.0) if left untreated. Recommendations can be made to treat ewes in lower BCS and leave a proportion of the higher body condition sheep untreated in a targeted selective treatment programme, to provide a population of non-resistant worms to delay the development of resistance.

Identification of amino acids associated with skeletal muscle growth in late gestation and at weaning in lambs of well-nourished sheep.

The objective of this study was to determine the association between intracellular free AA (FAA) profiles in skeletal muscle with muscle growth in twin and singleton fetuses in late pregnancy and at weaning, under an ad libitum feeding regime of the dam. Plasma from singleton- (n = 9) and twin-bearing (n = 10) ewes at d 140 of pregnancy and FAA in the semitendinosus muscle (STM) from the corresponding fetuses were studied. At weaning, intracellular STM FAA concentrations were compared between twins at the same age as singletons (Twin(age); n = 17) and at the same weight as singletons (Twin(wt); n = 17) to that of singletons (n = 20). Twin fetuses were 15% lighter (P = 0.03) with a 20% lighter STM (P = 0.02) compared to singletons. Maternal plasma FAA were similar (P ≥ 0.17) between singleton- and twin-bearing ewes. Twin fetuses had greater (P < 0.05) plasma concentrations of glutamine, histidine, and methionine and lower (P < 0.05) concentrations of aspartate, citrulline, glutamate, and ornithine compared with singletons. In fetal STM, twins had lower (P < 0.05) concentrations of aspartate and valine and greater (P < 0.01) concentration of methionine. Correlations were found between fetal STM weight and intracellular concentrations of arginine (r = 0.66, P < 0.01) and glutamine (r = 0.49, P < 0.01). Compared to singletons at weaning, Twin(age) were 16% lighter (P < 0.01) and the STM weight was proportionately 16% lighter (P < 0.01). For Twin(wt), the magnitude of the difference for STM weight was reduced to 8% lighter (P = 0.02). Compared to singletons, Twin(age) lambs had greater (P < 0.05) intracellular concentrations of glutamine, histidine, threonine, asparagine, alanine, serine, and glutamate but reduced taurine. The differences in FAA concentrations were less between Twin(wt) and singletons than between Twin(age) and singletons. Positive correlations were found between leucine, lysine, methionine, phenylalanine, proline, threonine, and tyrosine muscle concentration and STM weight at weaning. Males differed from females in intracellular FAA both in late pregnancy and at weaning. Twins had reduced RNA content during pregnancy and at weaning, suggesting a lower capacity for protein accretion. These data suggest that specific FAA concentrations are associated with differences in muscle growth during late pregnancy, notably arginine and glutamine, and reduced protein synthesis capacity. However, the relevance of specific FAA varies according to stage of development and sex of the lamb.

Avaliação metabólica do uso de probiótico ou monensina em cordeiros mantidos em semi-confinamento

The objective of this study was to verify probiotics and monensin effects on metabolic parameters in weaning lambs. In the experiment 1, thirty lambs divided in three groups were fed during 6 weeks. The lambs were enrolled in one of the following treatments: GC1: as a control, GB1: Bacillus cereus var. toyoi (1x106 spores/g) and GS1: Saccharomyces boulardii (1x106 viable cells/g). In the experiment 2, thirty lambs divided in three groups were fed during 8 weeks. The treatments consisted in GC2: as a control, GM2: monensin (500g/t) and GS2: Saccharomyces boulardii (1x106viable cells/g). In both experiments blood samples were collected weekly aiming to measure metabolic parameters as glucose, triacylglycerol (TAG), cholesterol, albumin, urea, aspartate amino transferase (AST), creatinine kinase (CK) and gamma glutamil transferase (GGT). The results from experiment 1 demonstrated that GS1 had greater (P&lt;0.05) concentrations of albumin and urea during the adaptation period. In the postadaption period the GC1 demonstrated increased (P&lt;0.05) concentrations of cholesterol, albumin and AST activity, in contrast, reduced (P&lt;0.05) concentrations of glucose, urea and CK in comparison to GS1. However, during experiment two throughout the adaptation period the GS2 had greater (P&lt;0.05) concentrations for albumin and urea. The GM2 had greater (P&lt;0.05) concentrations for TAG and lower (P&lt;0.05) for glucose and CK activity. During the post-adaption period the GS2 showed the lowest (P&lt;0.05) concentrations for cholesterol and GGT activity, GC2 had greater (P&lt;0.05) levels of albumin and AST activity as well as lower concentrations for urea. The GM2 had greater levels for GGT activity and lower levels for CK activity. Therefore, it is concluded that protein metabolism in lambs has better performance when Saccharomyces boulardii is added in the ration during the adaptation period. However, during post-adaptation period, monensin is more beneficial for the protein metabolism, once it does not interfere in the muscles catabolism.

Can animal genetics and flock management be used to reduce greenhouse gas emissions but also maintain productivity of wool-producing enterprises?

Farm intervention strategies that reduce greenhouse gas (GHG) emissions from the livestock industries may reduce global emissions associated with agriculture, though farmers are unlikely to adopt new practises unless they also improve farm profitability. Here our objective was to explore the effect of manipulating enterprise management or animal genotype on whole-farm production, profitability, enteric methane emissions and wool emissions intensities of sheep enterprises in southern Australia. Two enterprises that differed in lamb sale age were simulated using the model GrassGro; surplus animals were sold at either 18 weeks (weaner) or 12 months old (yearling). We examined the influence of lambing time (LT), joining maiden ewes at 7 months instead of 19 months of age (JA), increasing lamb weaning rates (WR), or superior genotypes with 10% improvement in fleece weight (FW), feed efficiency (FE) and/or methane yield (MY).Annual wool production, methane emissions, wool emissions intensities and profitability averaged across the baseline enterprises were 55 kg clean wool/ha, 3.2 t CO2-eq/ha, 31 kg CO2-eq/kg clean wool and $569/ha. Relative to these values average profitability increased by up to 18%, 15%, 10%, 9%, 8% and 0% for the JA, WR, FW, FE, LT and MY strategies; associated changes in wool production were 0%, −3%, 11%, 0%, 2% and 0%, and wool emissions intensities changed by −4%, −8%, −5%, −7%, 0% and −10%, respectively.Increasing weaning rate and introducing genotypes with lower methane yield afforded the greatest reductions in wool emissions intensities. Divergence between the relative effects of alternative strategies on farm economics, production and wool emissions intensities suggests that farm adaptations will depend on the goal of the individual farmer. If the goal is to increase profitability, flock management interventions are most beneficial; if the goal is to reduce emissions intensity, superior breeds containing improvements in several genetic traits have the greatest potential. We demonstrate that no intervention – to farm management, animal genotype or otherwise – is likely to achieve simultaneous improvements in all of production, profitability, net farm emissions and wool emissions intensity. Under current carbon prices, subsidies greater than $150/t CO2-eq would be required if economic returns from GHG abatement were to equal those from increased productivity, suggesting there would be little incentive for wool producers to participate in the Carbon Farming Initiative under the intervention strategies modelled here.