Lower Liveweight Gain Research Articles

Worms and welfare: Behavioural and physiological changes associated with gastrointestinal nematode parasitism in lambs

Parasitism with gastrointestinal nematodes (GIN) is a worldwide issue impacting negatively on animal production, health, and welfare. Therefore, early diagnostic signs of parasitism are required to allow for timely interventions. The objective of this study was to evaluate the behavioural and physiological changes in lambs associated with GIN infection. We used 30, 8-month-old Romney-cross wethers, that were administered anthelmintics until faecal egg counts (FEC) were zero and housed in an indoor facility. The study lasted 9 weeks, which comprised a 3-week pre-treatment, and a 6-week treatment phase. Lambs were randomly assigned to one of two treatments (n = 15/treatment) trickle-dosed with: 1) 1500 infective third stage larvae (L3) three days/week for 6 weeks (27,000 total L3; challenged), or 2) water 3 days/week for 6 weeks (control). Within each pen there were 5 pairs of lambs (balanced for liveweight), with each pair comprising a challenged and control lamb. Blood, faecal, and saliva samples were collected 1 week pre-treatment and weekly for 6 weeks of treatment. Behaviour was observed (e.g., feeding, lying, standing) from video-camera recordings using scan sampling every 5 min for 8 h, 1 day pre-treatment and on the day immediately prior to physiological sampling across the 6-week treatment phase (7 days in total). Accelerometers were attached to each lamb to continuously monitor behaviour from 3 weeks pre-treatment and for the remainder of the study. Liveweight, body condition, faecal soiling and faecal consistency scoring were performed weekly as was lipidomic analysis of plasma samples. From week 2 of treatment, challenged lambs spent less time feeding and more time lying than control lambs until week 5 of treatment (P ≤ 0.01). At week 3 of treatment, elevated lipids (mainly triglycerides and phospholipids), loose faeces and faecal soiling around the anus were observed in challenged lambs compared with controls (P ≤ 0.05). From week 4 of treatment, FEC were elevated in the challenged compared to control lambs (P ≤ 0.05). There was also lower liveweight gain at 4 and 5 weeks of treatment in the challenged lambs compared with control lambs (P ≤ 0.05). These results show a clear timeline of changes in behaviour (e.g., feeding and lying), lipids such as triglycerides, and digestive function (e.g., faecal soiling) suggestive of GIN subclinical disease, which show promise for use in future studies on early identification of subclinical GIN parasitism in lambs.

SIGNIFICANCE OF SEROLOGICAL MONITORING FOR POULTRY ORNITOBACTERIOSIS THERAPY

One of the main problems of poultry diseases is respiratory diseases. Among them a special place is occupied by ornithobacteriosis (ORT). Losses from ORT consist of: direct losses as a result of the disease - death of chickens, increased culling due to lameness, low live weight gain (up to 40%), reduction of carcass categories, reduction of egg production by 6-20%; indirect losses associated with the immune-suppressive effect of ornithobacteria, which increase the risk of other infections and prevent the formation of post-vaccination immunity. The diagnosis is established on the basis of epizootological data, clinical signs, pathological and anatomical changes, bacteriological and serological tests, positive bioassay. In most cases, infections caused by ornithobacteria are not diagnosed in time, the pathogen is difficult to isolate due to complications of other pathogens, or because experts are currently insufficiently aware of the ability of ORT to cause disease. ORT can be isolated by bacteriological method only at an early stage of the disease. The most relevant method of diagnosis is PCR. The advantage of the method is not only the isolation of DNA of individual cells of the pathogen in the sample, but also the ability to detect all serotypes. In addition, PCR is a successful diagnosis in the detection of ORT nucleic acid not only in tissue samples, but also in feces, eggs, dust, which is important for timely diagnosis. Enzyme-linked immunosorbent assay (ELISA) is used to control the presence of ornithobacteriosis in bird. The presence of antibodies to this pathogen in poultry of many species indicates its wide circulation.
 Thus, when conducting serological monitoring of blood serum from different age groups of broilers aged 1-44 days, the percentage of positive samples ranged from 40 to 100, which indicates the circulation of the field strain of the pathogen ornithobacteriosis. The percentage of positive serum from broilers to ORT was: from 1 to 5 days - from 88 to 50, from 6 to 10 days serum were negative, while at 17, 21 days and from 32 days to the end of cultivation (44 days) – 100 %. The percentage of positive batches at the end of fattening ranged from 42-53 days in the range from 75 to 100%, indicating the circulation of the field strain of the ornithobacteriosis pathogen antibiotic therapy against this disease.

Post‐grazing cutting management in tall fescue affects the sward structure, forage and liveweight production

AbstractTall fescue is the main perennial grass of the pastures of the temperate region of Argentina. However, after flowering in spring, tall fescue loses productivity and quality. Based on this, the objective of this work was to evaluate the effects of different post‐grazing mechanical cutting managements on the forage mass, leaf proportion, stocking rate, liveweight gain and liveweight production of tall fescue pastures. The treatments were post‐grazing mechanical cutting at anthesis (FC), post‐grazing mechanical cutting throughout spring and summer (SSC), and no post‐grazing mechanical cutting (NC). The experiment was performed from 2011 to 2014 in Argentina. The greatest and lowest forage mass were determined in September–November and May–September respectively. The leaf proportion of the SSC treatment was greater than that of the NC treatment, except in September–November. NC had higher stocking rate and lower liveweight gain than SSC, and neither NC nor SSC differed from FC. The liveweight production of the treatments was characterized by a trade‐off between stocking rate and liveweight gain. We conclude that FC is an attractive management because, with a single post‐grazing cutting, swards remain productive and leafy.

Mucuna pruriens seeds given in broiler diets on growth performance and carcass yield

The aim of this study was to evaluated the effect of soaked Mucuna pruriens (MP) seeds in tap water, acid or alkaline solution + cooking on its L-Dopa content and on the productive performance of broiler chickens. Ninety-six sexed chicks aged 21-days old with an initial live weight of 720 ± 80 g were used. Four diets were used, a control without MP (C) and three diets including 25 % MP: a) soaked MP in tap water + cooking (WMP); b) soaked MP in acetic acid solution + cooking (AAMP); c) soaked MP in calcium hydroxide solution + cooking (CHMP). The alkaline treatment reduced 71 % of L-Dopa in comparison to acid or water treatment (53 % and 41 % respectively). In the starter phase, the acid group had the lowest live weight gain (p<0.05) and highest feed conversion ratio when compared to control (p<0.05). Productive performance of birds fed with CHMP and C group was similar (p>0.05). In the finisher phase, there was not statistical difference in feed intake, live weight gain and feed conversion ratio among treatments (p>0.05). No differences were observed in carcass yield (p>0.05), but, the birds fed MP or AAMP had a heavier liver than birds on C group (p<0.05). Results shown that 25 % of CHMP can be used as feedstuff for broiler chickens without negative effects in their productive performance. Keywords: Velvet bean, L-Dopa, Poultry, weight gain.

The Effect of Corn-Expressed Carbohydrase on Performance and Digesta Viscosity of Broilers Fed a High Non-Starch Polysaccharide Diet

SUMMARY Study objectives were to determine the effects of a corn-expressed recombinant carbohydrase (AC1) on broiler performance and digesta viscosity in high non-starch polysaccharide (NSP) diets through 21 d of age. One day-old Hubbard × Cobb 500 chicks were assigned to 6 dietary treatments. Each treatment consisted of 12 replicate pens of 10 birds. The positive control diet (PC) was a corn and soybean meal formulation. The negative control diet (NC) included 10% wheat and 10% corn distiller’s dried grains with solubles (DDGS). The NC contained 100 kcal/kg less ME than the PC. Increasing inclusions of AC1 were applied to the NC to contain 50, 100, 200, and 400 U β-glucanase (β-Glu-U) per kg of feed. Preliminary experiments demonstrated AC1 homogeneity and stability post pelleting. Live weight gain (LWG) was the highest for PC fed birds from 1 to 14 d; however, birds fed NC with 400 β-Glu-U/kg had similar LWG as PC (P > 0.05). Day 1 to 21 FCR was lowest for PC fed birds; however, birds fed NC with 400 β-Glu-U/kg had similar FCR as PC (P > 0.05). Birds fed NC had lower LWG and higher viscosity than birds fed PC on day 14 (P 0.05). Birds fed NC with 200 or 400 β-Glu-U/kg had similar 14 d digesta viscosity as birds fed PC (P > 0.05). These data indicate that NSP ingredients may have a greater impact on digesta viscosity early in broiler growth and that AC1 at 200 and 400 β-Glu-U/kg produced similar results to PC.

Effects of phytase, calcium source, calcium concentration and particle size on broiler performance, nutrient digestibility and skeletal integrity

The study herein investigated the effect of mean particle size, calcium (Ca) source, Ca concentration and phytase on broiler performance, mineral digestibility and skeletal integrity from 1 to 28 days post-hatch. Sixteen dietary treatments were arranged in a 2 × 2 × 2 × 2 factorial design consisting of two Ca sources (limestone or a highly soluble calcium, HSC), two Ca concentrations (9.0 or 6.0 g/kg from Day 0 to Day 14 and 8.0 or 5.5 g/kg from Day 15 to Day 28), two Ca particle sizes (<0.5 or >0.5 mm) and two phytase-supplementation levels (0 or 1000 FTU/kg). Overall performance (Days 1–28) showed that the addition of phytase to diets containing 8.0 g/kg total Ca provided by HSC improved feed intake (P < 0.05), but there was no effect of the addition of phytase to birds fed Ca from limestone. Phytase supplementation decreased feed intake in birds fed limestone with a mean particle size >0.5 mm and increased feed intake in birds fed HSC with a mean particle size >0.5 mm, which resulted in a Ca source × Ca particle size × phytase interaction (P < 0.05). Birds fed diets containing HSC had a lower liveweight gain than did birds fed diets containing limestone (P = 0.03). Increasing the dietary Ca concentration from 5.5 g/kg to 8.0 g/kg total Ca decreased liveweight gain (P = 0.01). Phytase supplementation increased final liveweight gain (P < 0.001). Foot ash was observed to be higher in birds that received diets containing 8.0 g/kg Ca (P < 0.05). Phytase supplementation increased foot ash percentage (P < 0.05). Phytase increased Ca digestibility in birds fed diets containing Ca provided by HSC with a mean particle size <0.5 mm and diets containing limestone with a mean particle size >0.5 mm (P < 0.05). Phytase increased Ca digestibility in birds fed 5.5 g/kg Ca, but had no effect on Ca digestibility in birds fed 8.0 g/kg Ca (P < 0.05). The addition of phytase to diets improved the digestibility of phosphorus, especially in birds fed diets containing limestone (P < 0.05), or 8.0 g/kg total Ca (P < 0.05), or diets with a mean particle size >0.5 mm (P < 0.05). The results of the present study are consistent with those of previous studies by the authors, which have shown that low dietary Ca in conjunction with phytase improves broiler performance and mineral digestibility. Phytase improved growth performance, regardless of Ca source or Ca concentration and improved mineral digestibility.

The effect of replacing lactose by starch on protein and fat digestion in milk-fed veal calves

Replacing dairy components from milk replacer (MR) with vegetable products has been previously associated with decreased protein and fat digestibility in milk-fed calves resulting in lower live weight gain. In this experiment, the major carbohydrate source in MR, lactose, was partly replaced with gelatinized corn starch (GCS) to determine the effect on protein and fat digestibility in milk-fed calves. In total, 16 male Holstein-Friesian calves received either MR with lactose as the carbohydrate source (control) or 18% GCS at the expense of lactose. In the adaptation period, calves were exposed to an increasing dose of GCS for 14 weeks. The indigestible marker cobalt ethylenediaminetetraacetic acid was incorporated into the MR for calculating apparent nutrient digestibility, whereas a pulse dose of chromium (Cr) chloride was fed with the last MR meal 4 h before slaughter as an indicator of passage rates. The calves were anesthetized and exsanguinated at 30 weeks of age. The small intestine was divided in three; small intestine 1 and 2 (SI1 and SI2, respectively) and the terminal ileum (last ~100 cm of small intestine) and samples of digesta were collected. Small intestinal digesta was analysed for α-amylase, lipase and trypsin activity. Digestibility of protein was determined for SI1, SI2, ileum and total tract, whereas digestibility of fat was determined for SI1, SI2 and total tract. Apparent protein digestibility in the small intestine did not differ between treatments but was higher in control calves at total tract level. Apparent crude fat digestibility tended to be increased in SI1 and SI2 for GCS calves, but no difference was found at total tract level. Activity of α-amylase in SI2 and lipase in both SI1 and SI2 was higher in GCS calves. Activity of trypsin tended to be higher in control calves and was higher in SI1 compared with SI2. A lower recovery of Cr in SI2 and a higher recovery of Cr in the large intestine suggest an increased rate of passage for GCS calves. Including 18% of GCS in a milk replacer at the expense of lactose increased passage rate and decreased apparent total tract protein digestibility. In the small intestine, protein digestion did not decrease when feeding GCS and fat digestion even tended to increase. Overall, effects on digestion might be levelled when partially replacing lactose with GCS, because starch digestion is lower than that of lactose but fat digestion may be slightly increased when feeding GCS.

Spirulina (Spirulina platensis) algae supplementation increases microbial protein production and feed intake and decreases retention time of digesta in the rumen of cattle

Cattle consuming pastures low in protein have low liveweight gain due to low rumen degradable protein (RDP) supply and thus low microbial crude protein (MCP) production and efficiency of MCP production [EMCP, g MCP/kg digestible organic matter (DOM)]. Nitrogen supplements can increase MCP production and EMCP of cattle grazing low protein pastures. The objective of this study was to compare the effects of supplementation with a non-protein-N source (NPN), in this case urea and ammonium sulfate (US), with a single-cell algal protein source (Spirulina platensis), on intake, microbial protein supply and digestibility in cattle. Nine cannulated Bos indicus steers [initial liveweight 250.1 ± 10.86 (s.d.) kg] were fed Mitchell grass hay (Astrebla spp; 6.1 g N, 746 g NDF/kg DM) ad libitum and were supplied with increasing amounts of US (0, 6, 13, 19 and 33 g US DM/kg hay DM) or Spirulina 0, 0.5, 1.4, 2.5 and 6.1 g Spirulina DM/kg W.day in an incomplete Latin square design. The response of MCP production and EMCP to increasing amounts of the two supplements was different, with a greater response to Spirulina evident. The MCP production was predicted to peak at 140 and 568 g MCP/day (0.64 and 2.02 g MCP/kg W.day) for the US and Spirulina supplements, respectively. The highest measured EMCP were 92 and 166 g MCP/kg DOM for the US and Spirulina treatments at 170 and 290 g RDP/kg DOM, respectively, or a Spirulina intake of 5.7 g DM/kg W.day. Increasing RDP intake from US and Spirulina resulted in an increase in Mitchell grass hay intake and rumen NH3-N concentration and reduced the retention time of liquid and particulate markers and digesta DM, NDF and lignin in the rumen with greater changes due to Spirulina. Total DM intake peaked at a Spirulina supplement level of 4.6 g Spirulina DM/kg W.day with a 2.3-fold higher DOM intake than Control steers. Rumen NH3-N concentrations reached 128 and 264 mg NH3-N/L for the US and Spirulina treatments with a significant increase in the concentration of branched-chain fatty acids for the Spirulina treatment. The minimum retention time of liquid (Cr-EDTA; 23 and 13 h) and particulate (Yb; 34 and 22 h) markers in the rumen were significantly lower for Spirulina compared with US and lower than unsupplemented animals at 24 and 34 h for Cr-EDTA and Yb, respectively. Spirulina could be provided safely at much higher N intakes than NPN supplements. The results suggest that, at an equivalent RDP supply, Spirulina provided greater increases than US in MCP production, EMCP and feed intake of Bos indicus cattle consuming low protein forage and could also be fed safely at higher levels of N intake.

Carry-over effects of ewe nutrition and birth rank during the previous pregnancy on the milking performance during the subsequent lactation of Romney ewes

This study investigated whether selection for ewe size and nutrition during the previous pregnancy would affect the lactational performance of the ewe and liveweight gain of her lamb(s) in the subsequent year. A subgroup of singleton-bearing Romney ewes were milked once a week, for 7 consecutive weeks. Singleton-bearing ‘light’ ewes that gave birth to twins in the previous year had reduced milk yields from Day 21 of lactation (L21) onwards in the present year compared with those that gave birth to singletons in the previous year. Lambs born to light ewes had reduced liveweight gain from birth to L21 compared with those born to ‘heavy’ ewes. Singleton-bearing ewes in the present year that were fed maintenance and gave birth to twins in the previous year, produced less milk from L21 onwards compared with those that were maintenance-fed and singleton-bearing in the previous year. Singleton lambs born to milked ewes that were fed maintenance and gave birth to twins in the previous year, had lower liveweight gain from birth to L21 in the present year compared with lambs born to ewes fed maintenance and gave birth to singletons in the previous year. In the entire population, lambs born to ewes fed maintenance and that gave birth to twins in the previous year were lighter at L21 than lambs born to ewes fed ad libitum and bearing twins in the previous year. This indicates that if nutrition is suboptimal, or the ewes are lighter in the previous year, those that were twin-bearing are more likely to rear lighter lambs in the present year. Therefore, farmers need to take these points into consideration when devising feeding plans for the present year.

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 liveweight gain of 15‐month‐old Angus heifers during the first trimester of pregnancy on liveweight and milk intake of their calves

Nutritional methods of manipulating birthweight of calves would be beneficial for managing dystocia in beef heifers. Sixty‐five 15‐month‐old Angus heifers were managed under the following liveweight gain treatments for the first 42 days and then from 42 to 90 days of pregnancy: treatment 1: high liveweight gain throughout (881 ± 59 g/day and 212 ± 45 g/day); treatment 2: low liveweight gain throughout (182 ± 60 g/day and ‐565 ± 47 g/ day); and treatment 3: low then high liveweight gain (217 ± 59 g/day and 379 ± 44 g/day). Heifers were managed in one herd from day 90 of pregnancy until parturition. Birthweight of calves was not affected by treatment, and was 32.3 ± 0.9 kg, 32.9 ± 0.9 kg and 32.5 ± 0.9 kg for treatments 1, 2 and 3, respectively. Calves born to heifers in treatment 2 consumed less milk at 90 days of age than calves from heifers in the other treatments (P < 0.05). Liveweight gain restriction in the first trimester of pregnancy did not reduce birthweight of calves, and therefore could not be used to manage dystocia in heifers.

Comparison of Profitability of Cross and Native Breed Cattle Fattening Farms in Turkey

Yildirim, İ., Çiftçi, K. and Ceylan, M. 2009. Comparison of profitability of cross and native breed cattle fattening farms in Turkey. J. Appl. Anim. Res., 35: 17–20. To compare cross and native-breed fattening farms focusing on the profitability, data of 2006 production period were collected from 44 crossbreed and 14 native-breed fattening farms. The daily live weight gain per cross-breed cattle (909.4 g) was higher than that of native-breed cattle (558.2 g.). The profitability rate was +21.3% for cross-breed fattening farms maintaining >26 cattle. It was negative for cross breeding farms maintaining less cattle or the native breed farms due to low daily live weight gain, high production costs, feed intake inefficiency and low sales prices. The total production elasticity of input of cross-breed cattle fattening farms was 1.034, which means there existed an increasing return to scale.

Effects of liveweight gain during pregnancy of 15‐month‐old Angus heifers on dystocia and birth weight, body dimensions, estimated milk intake and weaning weight of the calves

First‐calving, 2‐year‐old heifers are particularly susceptible to dystocia caused by foeto‐maternal disproportion. Forty‐four 15‐month‐old Angus heifers were allocated to either a moderate (583 ± 73 g/day) or low (193 ± 71 g/day) liveweight gain treatment for the first trimester (93 days) of pregnancy. Both groups were of similar liveweight at parturition. Birth weight of the calves and incidence of dystocia were not significantly different between treatment groups at 33.0 ± 0.7 kg, compared with 33.8 ± 0.6 kg and 12% compared with 22% for the moderate and low groups, respectively. Body dimensions, liveweight from birth to 205 days of age and estimated milk intake of the calves were generally not affected by treatment. Assisted calves had greater estimated milk intake than unassisted calves at 37 days of age (5.9 ±1.0 versus 4.1 ± 0.6 kg/day; P < 0.05). Liveweight gain in early pregnancy did not affect birth weight of calves or the incidence of dystocia in 2‐year‐old heifers.

Willow ( Salix spp.) fodder blocks for growth and sustainable management of internal parasites in grazing lambs

A grazing experiment was conducted in the East Coast region of the North Island of New Zealand with 180 weaned ram lambs grazing typical dryland summer pasture versus grazing willow ( Salix spp.) fodder blocks. The experiment was conducted over a 14-week period with three forage treatments, comprising control pasture, restricted access to willow fodder blocks and full access to willow fodder blocks, with each treatment further divided into undrenched and regularly anthelmintic drenched groups. Live weight (LW) and dag score (DS) were recorded at 14-day intervals. Fifteen lambs in both drenched and undrenched groups were regularly monitored for faecal nematode egg counts (FEC) and nematode larval cultures (LC). Carcase weight (CW; kg) and LW (kg) data was collected from 12 additional lambs slaughtered at the beginning of the experiment to predict initial CW of the experimental lambs from their initial LW. At the end of the grazing experiment, all lambs were slaughtered in a commercial abattoir; CW and GR (fatness) was recorded. The abomasum and small and large intestines were collected from 10 lambs from each undrenched group for estimation of total worm nematode numbers. Organic matter digestibility (OMD; 0.65) and metabolisable energy (ME; 9.7 MJ/kg DM) content were similar for fodder block pasture and control pasture; the selected tree fodder had a higher OMD (0.71) and ME concentration (10.7 MJ/kg DM). Herbage condensed tannin (CT) concentration in willow fodder blocks was consistently higher than the trace CT levels detected in control pasture (14.5 g/kg DM versus 6.2 g/kg DM); tree fodder contained higher concentrations of CT (45.5 g/kg DM). Undrenched lambs grazing either control pasture or willow fodder blocks had lower LW gain (LWG) and CW gain (CWG) than lambs regularly drenched with anthelmintic (P<0.0001). Lambs grazing fodder blocks had consistently lower DS and carcase GR and undrenched lambs grazing fodder blocks had reduced worm burdens of economically important internal parasites compared with undrenched lambs grazing control pasture. Lamb growth rates were reduced by restricted access to willow fodder blocks (P<0.01), but not by full access. Undrenched lambs grazing fodder blocks with full access had similar LWG, final DS and carcase GR to regularly drenched lambs grazing control pasture (the conventional farming system), but had reduced rates of CWG. It was concluded that willow fodder blocks could have a place in integrated systems for the control of internal parasites in grazing lambs, leading to a reduction in anthelmintic drench use, but that this would probably result in lower CW relative to regularly drenched lambs.

Effects of feeding different ensiled forages on the productivity and nutrient‐use efficiency of finishing lambs

AbstractThe effects of offering ensiled red clover (Trifolium pratense), lucerne (Medicago sativa), pea (Pisum sativum), kale (Brassica oleracea) and hybrid ryegrass (Lolium hybridicum) on the productivity and nutrient‐use efficiency of lambs were investigated. Forages were cut, wilted for 24 h and ensiled as round bales. A hundred Suffolk‐cross lambs, aged 8 months, were offered grass silage during a 5‐week standardization period and then group‐housed for 14 d and offered ad libitum access to a treatment silage. For the measurement period, lambs were split into four replicate groups of five lambs per treatment. Dry matter intake and live weight were recorded every 7 d over 56 d. The chemical composition of the silages differed for all the variables measured. Lambs offered pea silage had a very low liveweight gain and this treatment was discontinued after 21 d. Lambs offered the other forages had a higher liveweight gain than lambs offered ryegrass silage (P &lt; 0·001). Food conversion and nitrogen‐use efficiency were higher in lambs offered the red clover, lucerne and kale silages compared with those offered ensiled ryegrass (P &lt; 0·001). These findings demonstrate the potential for using ensiled alternative forages rather than ryegrass to increase the productivity and nutrient use efficiency of livestock systems.

Willow fodder blocks—An alternate forage to low quality pasture for mating ewes during drought?

Two grazing experiments were conducted in the East Coast region of the North Island of NZ with ewes grazing on willow fodder blocks or control grass-based pastures during mating. Experiment I was conducted for 86 days with three treatments; short drought pasture (5–7 cm), long drought pasture (25–30 cm) and full access to willow fodder blocks which also contained long pasture (25–30 cm). Experiment II was conducted for 35 days with two treatments; control pasture and full access to willow fodder blocks. All ewe groups were combined at the end of mating and grazed on pastures until lambing and weaning. Live weight (LW) was recorded fortnightly during experimental grazing, body condition score (BCS) was scored monthly, and reproductive data was recorded at ultra-sound pregnancy scanning, lambing, docking and weaning. In Experiment I, short drought pasture and long drought pasture contained, respectively, a metabolisable energy (ME) of 8.2 and 9.6 MJ/kg dry matter (DM) and only traces of condensed tannins (CT). Herbage in the willow fodder blocks was intermediate in ME to short drought pasture and long drought pasture, whilst trees in willow fodder blocks contained 38 g of CT/kg DM and had a ME of approximately 10 MJ/kg DM. Willow fodder block herbage was consistently of higher legume content than drought pasture of similar mass. Ewes grazing short drought pasture lost 40 g/day of LW and had a low reproductive rate, as would occur in a drought situation, whilst ewes grazing long drought pasture gained LW and had a higher reproductive rate. Ewes grazing willow fodder blocks maintained LW and their reproductive performance was intermediate to ewes mated on long drought pasture and short drought pasture. Calculated intakes of DM, ME and crude protein (CP) were low for ewes grazing short drought pasture and higher and similar for the other two groups, while intake of secondary compounds was much higher for ewes grazing willow fodder blocks. In Experiment II, ewes mated on willow fodder blocks had lower LW gain than ewes mated on control pasture, but reproductive performance was similar for both groups. Willow fodder blocks are a useful source of supplementary feed during droughts, but the grazing management that optimizes animal performance needs further research.

Effect of different levels of cactus ( Opuntia ficus-indica) inclusion on feed intake, digestibility and body weight gain in tef ( Eragrostis tef) straw-based feeding of sheep

The study was conducted to determine the effect of different levels of cactus ( Opuntia ficus-indica) inclusion on feed intake, diet apparent digestibility and live weight gain in tef ( Eragrostis tef) straw-based feeding of sheep. A randomized complete block design was used to assign 24 male Highland sheep with initial live weight of 17.0 ± 3.9 kg (mean ± S.D.) in six replications to one of the four treatment feeds. The animals in T1 were offered 610 g tef straw on dry matter (DM) basis, and 57.6 g DM noug ( Gouzotia abyssinica) seed cake, and those in T2, T3 and T4 were offered the same quantities of noug seed cake DM with replacement of one fourth, half and three fourths of tef straw DM with spineless cactus DM, respectively. The sheep were kept on the experimental feeds for 118 days. Spineless cactus and tef straw were offered separately to animals in two equal portions at 8:00 and 16:00 h. Common salt and fresh water were offered ad libitum throughout the experimental period. Spineless cactus had a high content of water (880 g/kg fresh weight), ash, especially calcium (45 g/kg DM), but the phosphorus concentration was 2.6 g/kg DM, making the ratio of calcium to phosphorus 17:1. The soluble carbohydrate of cactus was over 251 g/kg DM, whereas it was only 130 g/kg DM in the basal diet. The crude protein (CP) content of cactus (83 g/kg DM) was higher compared to that of the basal feed (76 g/kg DM). High contents of neutral detergent fiber (NDF) (705 g/kg DM) and acid detergent fiber (ADF) (386 g/kg DM) were determined in tef straw than in cactus that had NDF content of 392 g/kg DM and ADF content of 263 g/kg DM. Cactus was readily consumed and the animals preferred cactus to tef straw. The water intake was negatively correlated ( r = −0.88) with cactus intake. Significant differences (P<0.05) were observed between treatments in daily live weight gain and the highest live weight gain (53 g/day) was recorded in sheep fed on T3, whereas the lowest live weight gain (23 g/day) was recorded in animals on T1. The digestibility coefficients for CP, NDF and ADF reduced as the cactus level increased in the diet. It is concluded that inclusion of cactus in the experimental diet or other comparable diets to up to 50% on DM basis for sheep fed tef straw promotes weight gain without causing digestive disturbances common in diets with high cactus inclusion.

The effect of genetic merit for milk production and concentrate feeding level on the reproductive performance of Holstein-Friesian cows in a grass-based system

AbstractThe objective of the study was to evaluate the effect on reproductive performance of varying level of concentrate supplementation with both high and medium genetic merit cows in a spring calving grass-based system of milk production. The effect of year, cow genetic merit for milk production and concentrate feeding level on milk production, body condition score, live weight, blood metabolites and dry-matter (DM) intake were studied. A repeated measures model with a factorial arrangement of genetic merit and concentrate feeding level was used to do this. Associations between these variables and pregnancy to first service (PREG1), pregnancy to first and second service (PREG12) and overall pregnancy (PREG) rates were assessed using logistic regressions for year 2.Cows were grouped into high (HM) and medium (MM) genetic merit based on their pedigree indices for milk production (PD milk). The HM cows had a PD milk of + 276 (s.d. 100) kg, while the MM cows had mean PD milk of + 81 (s.d. 95) kg. Within genetic merit groupings, cows were assigned to one of three concentrate feeding levels; low (LC), 376 kg; medium (MC), 810 kg; and high (HC), 1540 kg of concentrate per cow per lactation. In year 1, all 78 cows were second lactation animals, while in year 2, 71 cows (previously in year 1) were third lactation and 12 second lactation. All cows calved between February and April, and were presented for rebreeding from late April until late July each year.When treatment means were compared, genotype and concentrate feeding levels had no significant effects on reproductive performance while year was significant for most parameters. Comparing year 2 to year 1 pregnancy rate to first service (P 0•001; 37 v. 64%), pregnancy rate to first and second service (P &lt; 0•05; 64 v. 81%), overall pregnancy rate (P &lt; 0•05; 78 v. 92%) were lower. Also in year 2, cows had significantly higher milk yields at first insemination (36•9 v. 32•3 kg per cow per day), greater live-weight losses from calving to first insemination (-86 v. –53 kg per cow), lower live-weight gain in the 90 days after their first insemination (+ 24•6 v. + 34•2 kg per cow), higher DM intake (20•6 v. 17•3 kg DM per cow per day) and lower plasma glucose concentrations (3•18 v. 3•61 mmol/l) than in year 1.In year 2, there were significant negative associations between the likelihood of PREG12 and both PD milk and live-weight gain in the 90 days after first insemination. The results of this study indicate that continued selection for increased milk production, resulting in greater partitioning of energy to milk production rather than body reserves will reduce reproductive performance and offering higher levels of concentrate supplementation may not alleviate this problem.

Effects of genotype and dietary forage to concentrate ratio during the finishing period on carcass characteristics and meat quality of lambs from hill sheep systems

The study investigated the effects of lamb genotype produced from hill flocks on feed efficiency, carcass characteristics and meat quality in animals finished on either a high forage:concentrate ratio diet (HFC) or a low forage:concentrate ratio diet (LFC). Purebred Scottish Blackface (BXB) lambs were compared with Blue-Faced Leicester×Scottish Blackface (BLXB) and Texel×Scottish Blackface (TXB) lambs. Purebred Cheviot (CXC), Suffolk×Cheviot (SXC) and Texel×Cheviot (TXC) lambs were also investigated. Lambs on the LFC diet were offered grass silage and concentrates mixed in the proportion of 0·80 silage and 0·20 concentrates on a dry matter basis. The LFC diet consisted of 0·20 grass silage and 0·80 concentrates on a dry matter basis. Representative lambs were slaughtered at the start of the experiment and on reaching 38 and 46 kg live weight. Averaged over the two slaughter weights, within the Blackface cross lambs, BXB had a lower liveweight gain (P &lt; 0·01) than either BLXB or TXB (138, 207 and 203 (S.E. 11·1) g/day, respectively). Within the Cheviot cross lambs, CXC had a lower liveweight gain (P &lt; 0·05) than SXC (188 v. 220 (S.E. 11·1) g/day), while SXC and TXC (204 g/day) had similar liveweight gains. Lambs on the LFC diet had a higher dressing proportion (P &lt; 0·001) compared with lambs finished on the HFC diet (0·466 v. 0·434 (S.E. 0·0018) kg carcass per kg live weight). Averaged over the two slaughter weights BXB lambs had a lower (P &lt; 0·05) dressing proportion than the other genotypes. Carcass conformation classification (assessed on a five-point scale) was higher (P &lt; 0·001) in lambs finished on the LFC diet (3·0 v. 2·4 (S.E. 0·04)). Conformation classification was higher in lambs produced from Cheviot compared with Blackface ewes (P &lt; 0·05). Within the Blackface cross lambs, BXB and BLXB lambs had a lower conformation classification (P &lt; 0·001) than TXB lambs (2·4, 2·4 and 2·9 (S.E. 0·08) respectively). Within the Cheviot ewes, TXC lambs had a higher (P &lt; 0·001) classification than either CXC or SXC (3·1, 2·7 and 2·7 (S.E. 0·08) respectively). Lambs finished on the LFC diet had a higher fat classification score compared with lambs on the HFC diet (P &lt; 0·001) (3·4 v. 2·8 (S.E. 0·04)). Fat classification was similar across all genotypes. Lambs finished on the LFC diet had a lower ash content in the carcass than lambs finished on a HFC diet (P &lt; 0·01) (44 v. 47 (S.E. 0·8) g/kg). Lamb genotype and dietary forage:concentrate ratio had no significant effect on cooking loss, sarcomere length, Warner–Bratzler shear force and L* values. Ultimate pH (pHU) was not influenced by dietary forage:concentrate ratio, but was significantly (P &lt; 0·01) higher in BXB lambs compared with BLXB, TXB, CXC and TXC lambs. Lambs offered the LFC diet during the finishing period had significantly higher values for a* (P &lt; 0·05), b* (P &lt; 0·001), C* (P &lt; 0·001) and H0 (P &lt; 0·05) than lambs offered a HFC diet. Of these parameters only b* was significantly affected by lamb genotype, with BXB lambs having a lower value (P &lt; 0·05) than the other genotypes.

The effect of cow genetic index and grass-based feeding system on the performance of spring-calving Holstein-Friesian cows in second lactation

AbstractThe objective of this study was to investigate the effect of both cow genetic index (CGI) and feeding system on the performance of second lactation Holstein-Friesian dairy cows on grass-based feeding systems. There was no interaction between CGI and feeding system for any of the parameters measured. Cows of high genetic index (HGI) produced significantly higher yields of milk (P &lt; 0.001), fat (P &lt; 0.001) protein (P &lt; 0.0001) and lactose (P &lt; 0.001) than medium genetic index cows (MGI). CGI had no effect on the concentration of milk constituents. Averaged across four intake measurements the HGI cows had significantly (P &lt; 0.001) higher grass dry-matter intake (GDMI) and total dry-matter intake (TDMI). Live weight was similar for both genotypes during lactation. The HGI cows had significantly (P &lt; 0.05) higher live-weight loss in the first 10 weeks of lactation, significantly lower live-weight gain from week 10 to the end of lactation and higher (P &lt; 0.05) live-weight gain during the dry period. Condition score was significantly lower with the HGI (P &lt; 0.001) at all stages of lactation. There was a higher proportion (P &lt; 0.05) of the HGI cows non-pregnant at the end of the 13-week breeding season. Feeding system had a significant effect on the yield of milk (P &lt; 0.001), fat (P &lt; 0.001), protein (P &lt; 0.001) and lactose (P &lt; 0.001). Feeding system B produced significantly higher (P &lt; 0.05) milk yield and yield of constituents (when compared with feeding systems A and C). Over the period when feeding systems were being applied, feeding system C had significantly higher (P &lt; 0.05) milk protein concentration. Feeding system had a significant effect (P &lt; 0.001) on both GDMI and TDMI. Feeding system had no effect on live weight, condition score or fertility performance.