Recent Submissions

  • Abstracts of papers presented at the 33rd Foodscience and Technology Research Conference, University College, Cork

    various; Hanrahan, J. P. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
  • Colour of subcutaneous adipose tissue and muscle of Irish beef carcasses destined for the Italian market.

    Dunne, Peter G.; O'Mara, Frank P.; Monahan, Frank J; Moloney, Aidan P (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The purposes of this study were (i) to objectively measure the colour of carcass fat and muscle of heifers that had been previously selected, subjectively, for the Italian market and (ii) to define instrumental colour values which would describe the required fat colour for that market. On one day during each of 5 months (11 April, 13 June, 10 October, 10 November and 19 December) the ‘b’ (yellowness) value of carcass fat was measured at two positions (proximal pelvic limb area and the area between 9th rib and 4th lumbar vertebra) and the ‘L’ (lightness) and ‘a’ (redness) values of two muscles (M. longissimus dorsi (LD) and M. rhomboideus thoracis (RT)) were measured using a Minolta chromameter. Measurement date had a significant effect (P < 0.05) on ‘b’ values of fat at both positions, with carcasses displaying the most yellow fat on 13 June (P < 0.05). The LD was palest and most red on 11 April (P < 0.05) and the RT tended to be palest on 13 June but most red (P < 0.05) on 11 April. The ‘L’ value differed between muscles on 11 April (P < 0.01) and 19 December (P < 0.05) and the ‘a’ value differed between muscles on all dates except 13 June. The majority of carcasses on each date fell between muscle ‘L’ values of 31 and 35, regardless of muscle, and between muscle ‘a’ values of 18 and 22. It is concluded that application of a “cut-off” value to muscle colour would be futile but as 81% of accepted carcasses had fat ‘b’ values below 14.2, regardless of position, that this could be used as a threshold of acceptable yellowness.
  • The effect of dietary crude protein concentration on growth performance, carcass composition and nitrogen excretion in entire grower-finisher pigs

    Carpenter, D. A.; O'Mara, Frank P.; O'Doherty, John V (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Two experiments, a performance experiment (n = 72) and a nitrogen balance (n = 16) experiment were conducted to evaluate the effects of dietary crude protein (CP) concentration on growth performance, carcass characteristics and nitrogen excretion of pigs. Dietary CP concentrations in experimental diets (g/kg) were 207.5, 170, 150 and 122.5 for treatments 1, 2, 3 and 4, respectively, and were offered to individually-fed entire-male grower-finisher pigs (45 to 95 kg). The diets were formulated to contain 13.7 MJ digestible energy and 11 g total lysine/per kg. Synthetic lysine, methionine, threonine and tryptophan were added to achieve ideal protein status. There was a linear increase in food intake as CP concentration decreased (P < 0.05). There was a quadratic response in daily live-weight gain and food conversion ratio (P < 0.05) to the change in CP concentration (P < 0.05), with an improvement in daily gain and food conversion ratio occurring as CP concentration declined to 150 g/kg and a deterioration in these parameters thereafter. There was a linear decrease (P < 0.05) in lean meat proportion as CP concentration decreased. There was a linear decrease in urinary output (P < 0.05), urinary pH (P < 0.01) and slurry pH (P < 0.05) as dietary CP concentration decreased. There was a quadratic response in urinary nitrogen output (P < 0.05), total nitrogen output (P < 0.05) and N utilization as dietary CP decreased. In conclusion, a dietary CP level of 150 g/kg was optimal in terms of growth performance and reduced nitrogen excretion.
  • Genetic relationships among linear type traits, milk yield, body weight, fertility and somatic cell count in primiparous dairy cows

    Berry, Donagh P.; Buckley, Frank; Dillon, Pat; Evans, Ross D; Veerkamp, Roel F (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Phenotypic and genetic (co)variances among type traits, milk yield, body weight, fertility and somatic cell count were estimated. The data analysed included 3,058 primiparous spring-calving Holstein-Friesian cows from 80 farms throughout the south of Ireland. Heritability estimates for the type traits varied from 0.11 to 0.43. Genetic correlations among some type traits were very strong and may indicate the possibility of reducing the number of traits assessed on each animal; the genetic correlation between angularity and body condition score was –0.84. Genetic correlations between all type traits (except body condition score, udder depth and teat length) and milk yield were positive and ranged from 0.08 to 0.69. The possibility of selecting for body weight may be achievable within a national progeny-testing programme using type traits within a selection index. Moderate to strong genetic correlations existed between some type traits and the various fertility measures and somatic cell count indicating the opportunity of indirect selection for improved fertility and health of animals using type traits within a selection index; however, the standard errors of some of the genetic correlations were large and should thus be treated with caution. Genetically taller, wider, deeper, more angular cows with tighter, stronger, shallower udders were predisposed to have inferior pregnancy rates to first service and require more services.
  • Development of enterococci and production of tyramine during the manufacture and ripening of Cheddar cheese

    Rea, Mary C.; Franz, C.M.A.P.; Holzapfel, W.H.; Colgan, T.M. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The effect of six strains of enterococci (three strains of Enterococcus faecalis, and one strain each of Ec. faecium, Ec. durans and Ec. casseliflavus) on flavour development and tyramine production in Cheddar cheese during manufacture and ripening was studied in two trials. No strain produced gelatinase or haemolysin and all of them grew well during manufacture reaching 107 colony forming units (cfu)/g in 6 h, after which they remained more or less constant during at least 48 weeks of ripening. There was no relationship between tyramine production in a broth containing tyrosine and tyramine production in the cheese. All strains, except Ec. casseliflavus, produced tyramine in the cheese, with the greatest concentration (162 mg/kg) being produced by Ec. durans after 9 months ripening at 8 ºC. There was no statistically significant difference (P > 0.05) between the flavour of the control cheese and any cheese containing an enterococcus. Nevertheless, cheese made with Ec. faecium E-24 received the best score in each trial at both time points. No off-flavours were found. Regarding proteolysis, only Ec. faecalis E-140 showed significant (P < 0.05) increases in both phosphotungstic acid and pH 4.6 soluble N. It is concluded that enterococci have little effect on the flavour of Cheddar cheese.
  • Effects over time of fertiliser P and soil series on P balance, soil-test P and herbage production

    Herilhy, Mary M.; McCarthy, J.; Breen, James; Moles, Richard (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Quantification of the balance between P input and offtake (P balance), and the consequent effect on soil-test P, is essential for management of sustainable soil and fertiliser nutrient supply. Results of measurements on 31 cut swards showed that change in P balance over 4 years was significantly affected by both P treatment and soil series. The more negative P balances were in high-P soils, and in soils of non-limestone parent material compared with limestone parent material. Initial mean Morgan P of 4.3 and 12.6 mg/l, in low and high index groups (0 to 6.0 and ≥6.1 mg/l) decreased to 1.7 and 4.4 mg/l after 4 years with no P treatment, in response to annual changes of ca. 25 to 35 kg/ha in P balance. Decreases were progressively smaller with increased P input, and smaller in non-limestone than limestone soils. The ratio of negative P balance to change in Morgan P varied from 20:1 to 70:1 depending on soil P index and parent material. Five sites gave a response to P in the final year following annual P inputs of 20 and 40 kg/ha, although Morgan P was ≤3.0 mg/l at 12 sites in the preceding autumn and 3.1 to 6.0 at nine sites. The results showed that both P balance and soil series should be taken into account in efficient fertiliser management, and that data from cut swards can be extrapolated to grazed swards when adjusted for P offtake. However, the results did not support the assumption that inputs balance offtakes in direct proportion.
  • Note on a portable simulator for analysis of milking machine porformance

    O'Callaghan, Edmund, J. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    A portable flow simulator was developed for recording vacuum variations in commercial milking machine clusters. The cluster in the milking unit under evaluation was mounted on the frame of the simulator and the flow of water through each liner was regulated by separate flow meters. By placing an artificial teat into the liners the flow characteristics during actual milking were simulated. Measurement vacuum sensors were mounted in the claw, in one artificial teat, in the pulsation chamber and in the milk pipeline. Analog and digital outputs were recorded. The system was validated by comparing the outputs with those obtained with a laboratory flow simulator and with recordings taken during cow milking. The recordings with the portable simulator and the laboratory simulator were identical; the profiles of the analogue signals obtained with the portable simulator and from cow milking were similar. The portable flow simulator will allow recording of vacuum variations in commercial milking machines during simulated or actual milking.
  • Effects of the design of a milking unit on vacuum variations during simulated milking

    O'Callaghan, Edmund, J. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The vacuum variations at the apex of an artificial teat during simulated milking were measured in a factorial-design laboratory test involving six cluster types, two internal diameters (13.5 mm and 16 mm) of long milk tube (LMT), three water flow rates (4, 6 and 8 l/min), simultaneous (4 × 0) and alternate (2 × 2) pulsation patterns and three pulsator ratios (60, 64, and 68%). Four of the six clusters were fitted with wide-bore tapered liners and represented all combinations of two claw volumes (150 or 420 ml) and two short-milk-tube bores (8.5 mm and 13.5 mm). Two clusters were fitted with narrow-bore liners (22 and 25 mm) that had large-bore short milk tubes and large claw volumes. The vacuum variations were expressed as mean vacuum at the teat-end during the b-phase of pulsation (TVB), mean vacuum at the teat end measured over complete pulsation cycles (TV), minimum vacuum measured over complete pulsation cycles (TVM) and amplitude of vacuum fluctuation measured over complete pulsation cycles (TVF). The highest level of TVB was recorded with wide-bore tapered liners. For a milking unit fitted with a wide-bore tapered liner TVF was reduced and TVM increased by increasing either the bore of the short milk tube or the volume of the claw. When the bore of the LMT was increased TVB, TV and TVF increased. Simultaneous pulsation gave higher TVB (P < 0.001) and higher TVF (P < 0.001) than alternate pulsation for all cluster types. The overall effects of altering pulsator ratio were significant but small in practical terms. There were significant interactions between cluster type and water flow rate and pulsation pattern for TVB, TV, TVM and TVF.
  • A note on the effects of test-end vacuum on milking characteristics

    O'Callaghan, Edmund J.; Gleeson, David E (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The magnitude of vacuum applied to the teat end can have a major effect on milking characteristics. While milking vacuum is usually measured in the milk pipeline, the teat-end vacuum during milk flow depends on the configuration of the milking unit. The objective was to establish the effect of teat-end vacuum, recorded during flow simulation, on actual milking time, milk yield, and both mean and peak milk-flow rates. Four configurations of milking units were set up to give vacuum levels of 35, 38, 40 and 42 kPa at the apex of an artificial teat during simulated milking. The experiment involved a latin square design with four groups of Friesian cows (14/group), four 2-day periods and four treatments (vacuum level). Altering the vacuum level had no significant effect on milk yield. There were no differences in milking characteristics between vacuum levels of 38 and 40 kPa. A vacuum level of 42 kPa gave a shorter milking time (P < 0.001), higher average milk-flow rate (P < 0.01) and higher peak milk-flow rate (P < 0.001) than the three lower vacuum levels. Milking time was significantly longer (P < 0.001) and peak milk-flow rate lower (P < 0.001) with a vacuum of 35 kPa compared to other vacuum levels.
  • Surveys of cereal diseases in Northern Ireland, 1976 to 2000

    Mercer, P. C.; Ruddock, A. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    A number of disease surveys was carried out on the three main cereals grown in N. Ireland from 1976 to 2000, namely spring and winter barley and winter wheat. Although not all crops were surveyed in each year, the surveys provide a good picture of changes in disease spectra over the years. The most dramatic change in spring barley disease has been the almost complete disappearance of Blumeria graminis (mildew) and its replacement as the dominant disease by Rhynchosporium secalis (leaf blotch). Leaf-spotting ascribed to physiological causes also became more common in the latter years of the surveys. The disease spectrum of winter barley was more consistent from year to year, with Rhynchosporium secalis as the most common pathogen. Barley yellow dwarf virus was relatively severe in 1984, but in no other years. In winter wheat, there was a major change with the almost complete eclipse of Phaeosphaeria nodorum leaf blotch by Mycosphaerella graminicola (septoria tritici blotch). Gaeumannomyces graminis (take-all) was frequently severe. Surveys of cultivar popularity generally showed a rapid change in varieties over a relatively short time. Surveys of fungicide usage tended to show an increase in numbers of sprays applied, in spite of the fact that commercial pressures should have been acting towards a reduction in spraying.
  • Effect of feed on cholesterol concentration and oxidation products development of longissimus dorsi muscle from Iberian pigs

    Rey, A.I.; Lopez-Borte, C.J.; Buckley, J.D. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The effect of dietary free-range feeding or supplementation with copper and/or vitamin E in confinement on total cholesterol, neutral and polar lipids and cholesterol oxidation of the longissimus dorsi muscle from Iberian pigs was studied. Free-range fed pigs had higher (P=0.001) contents of γ-tocopherol and lower concentrations of α-tocopherol in the muscle than pigs fed diets supplemented with 100 mg/kg vitamin E. The total cholesterol content of the muscle was not significantly affected by the diets. However, the cholesterol:phospholipid ratio was higher (P<0.05), and consequently the membrane fluidity was lower, in the free-range fed pigs than in the pigs fed in confinement with either copper-supplemented (P<0.05) or vitamin E-supplemented (P<0.01) diets. The proportion of saturated fatty acids in phospholipids was greater (P<0.05) in the free-range fed group, which suggests metabolic regulation to maintain membrane structure. Free-range feeding produced higher levels of free fatty acids (P<0.01), lysophosphatidylcholine (P<0.05) and phosphatidylserine (P<0.01) and lower cholesterol esters (P<0.01) and sphingomyelin (P<0.05) in the muscle than the other groups. The ratios of phosphatidylethanolamine:phosphatidylcholine and sphingomyelin: phosphatidylcholine, which are indicators of membrane fluidity, were not significantly affected in any group. Dietary α-tocopheryl acetate supplementation produced lower β-epoxide (P<0.01), 7β-OH (P<0.05), and total cholesterol oxides (P<0.01) in cooked muscle after refrigerated display than in the other groups. These results indicate that supplementation with dietary α-tocopheryl acetate is more effective in reducing cholesterol oxidation than free-range feeding in cooked muscle from Iberian pigs. In evaluating oxidation, the composition of the muscle and meat treatment have to be considered as well as membrane fluidity.
  • Rearing calves outdoors with and without calf jackets compared with indoor housing on calf health and live-weight performance

    Earley, Bernadette; Murray, Margaret; Farrell, J.A.; Nolan, Marie-Jean (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The objective of this study was to compare the effects of rearing calves outdoors, with and without all-weather calf jackets, with calves reared indoors on calf immunity and animal performance. In February 1999, male Holstein calves (mean (s.e.) weight 55 (1.90) kg) were randomly assigned to one of three treatments (n=30 per treatment): 1) outdoors with jacket, (J; mean age 19 (s.e. 2.0) days); 2) outdoors without jacket (NJ; mean age 19 (s.e. 1.8) days), and 3) indoors on straw (I; mean age 19 (s.e. 1.0) days). Calves received an individual allowance of 25 kg of milk replacer dry matter during the first 42 days with ad libitum access to a concentrate ration from day 0 to 63. The jackets were removed from the calves on day 42. Live-weight gain from day 0 to day 63 of the study was not significantly different between treatments (J, 0.79; NJ, 0.80; I, 0.80 kg). Sixty percent of the J calves and 53% of the NJ calves required four or more antibiotic treatments for respiratory disease while corresponding treatments were required for 97% of the I calves. The incidence of diarrhoea was significantly higher in both outdoor treatments compared to the I treatment. There was no significant difference in white blood cell counts or in serum immunoglobulin concentrations between treatments on days 0, 21, 42 and 63 or in in vitro interferon-γ production on day 63. It is concluded that using calf jackets on calves reared outdoors had no beneficial effect on calf performance or immune status. The incidence of respiratory disease was higher and diarrhoea incidence was lower in calves reared indoors compared with calves reared outdoors. There was no significant difference in incidences of diarrhoea and respiratory disease between the two outdoor treatments.
  • Comparison of concentrates or concentrates plus forages in a total mixed ration or discrete ingredient format: effects on beef production parameters and on beef composition, colour, texture and fatty acid profile

    Cooke, D.W.I; Monaghan, Frank J; Brophy, P.; Boland, Maurice (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Diets consisting primarily of concentrates or of concentrates plus silage in a total mixed ration (TMR) or discrete ingredient format were compared for effects on beef production traits and on beef quality. Sixty continental cross heifers (377 kg, s.d. 31) were allocated to one of the following feeding regimens for 96 days pre-slaughter: (i) a control ration of grass silage, maize silage, a cereal-based concentrate and straw at proportionately, 0.23, 0.15, 0.59 and 0.03 of dietary dry matter, respectively; (ii) a total mixed ration (TMR) with the same dietary ingredients as the control ration; (iii) a high concentrate ration (HC) of a cereal-based diet and straw at proportionately 0.95 and 0.05 of dietary dry matter, respectively. Subcutaneous fat samples were taken from all animals at slaughter and the strip-loin was excised from 10 animals per group for colour, texture and fatty acid determination. The HC and TMR groups had higher (P < 0.05) daily live-weight gain, slaughter weight and carcass weight than the control group. Muscle protein was highest (P < 0.01) in the TMR group while muscle marbling was highest (P < 0.01) in the HC group. Subcutaneous fat from the HC group was less (P < 0.001) yellow than fat from the other groups. Fatty acid analysis of intramuscular fat showed that the HC group had higher C18:1 and lower C18:3 proportions than the control group (P < 0.05). The n-6:n-3 fatty acid ratio of intramuscular fat from the HC group was higher (P < 0.05) than that of the other groups. The results suggest that, at similar feed intakes, TMR feeding offers advantages for beef production over feeding ingredients separately, and yields muscle with a higher protein concentration, while high concentrate feeding yields whiter subcutaneous fat and intramuscular fat with a less nutritionally favourable n-6:n-3 fatty acid ratio.
  • Analysis of DRB1 exon 2 genotyping by STR size analysis in Suffolk and Texel sheep breeds

    Sayers, Gearoid; Mitchel, S; Ryan, Marion T; Stear, M.J.; Hanrahan, James P; Sweeney, Torres (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Alleles of the DRB1 exon 2 locus of the major histocompatibility complex have recently been associated with genetic resistance to gastrointestinal nematodes in sheep. While sequence-based typing is the standard method for allele discrimination, a rapid, high throughput method for DRB1 exon 2 genotyping is required if such information is to be incorporated into national breeding programmes. Previous studies have highlighted a simple tandem repeat (STR) located within intron 2 of the DRB1 gene, which could potentially be used to accurately assess the allele present within the adjacent exon 2. The aims of this study were firstly to compare two methods of STR analysis, Genescan™ and autoradiography, and secondly to investigate if STR analysis of DRB1 intron 2 could be used to accurately assess the profile of DRB1 exon 2. Six DRB1 exon 2 alleles were identified by sequence-based typing in Suffolk (n = 31) and eight in Texel (n = 60) sheep. The results indicated that Genescan™ was a more accurate method of STR analysis than autoradiography. The expected 1:1 correspondence between STR size, analysed by Genescan™ and DRB1 exon 2 allele, determined by sequence-based typing, was not observed. However, the correspondence was found to be degenerate, whereby some alleles were associated with two STR sizes. Thus, irrespective of the STR size identified, STR analysis by Genescan™ identified the correct allele in all cases within both populations of animals studied. However, the Genescan™ method of allele identification cannot be used for Suffolk × Texel crossbred progeny or in other breeds where the relationship between STR size and DRB1 exon 2 allele is not known.
  • Effect of suckler cow genotype and nutrition level during the winter on voluntary intake and performance and on the growth and slaughter characteristics of their progeny

    Drennan, Michael J; McGee, Mark (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    A 4-year study comparing Hereford × Friesian (HF) and Limousin × Friesian (LF) spring-calving cows and two grass silages on the performance of suckler cows and their progeny was undertaken using 163 cows. Cows were offered, to appetite, grass silage of either low (L) or moderate (M) digestibility in late pregnancy and early lactation. Cows and their calves spent from April until weaning in October at pasture. Bulls were slaughtered at 16 months of age and heifers at 20 months of age. There was no significant effect of cow genotype on dry matter (DM) intake, annual live-weight change or reproductive performance but annual body condition score gain was higher (P < 0.05) for HF than for LF cows. Cows offered the M silage had higher (P < 0.001) DM intake, lower winter live-weight loss (P < 0.001) and lower (P < 0.01) live-weight gain at pasture than cows offered the L silage. Calf birth, weaning and slaughter weights were not significantly different (P > 0.05) between genotypes. The male progeny of LF cows had a higher kill-out proportion (P < 0.001) and carcass weight (P < 0.05) and lower (P < 0.05) carcass fat score than HF cows. Compared to the M silage, the male progeny from cows offered the L silage had a greater daily gain from birth to slaughter (P < 0.05), slaughter weight (P < 0.05) and carcass weight (P < 0.05). The corresponding differences for female progeny were in the same direction but were not statistically significant.
  • Comparison of flail-harvested, precision-chopped and round-bale silages for growing beef cattle

    Charmley, E; Firth, S (Irish Journal of Agricultural and Food Research, 2004)
    The effects of silage conservation method on silage composition and animal performance were examined in two experiments. In Experiment 1, unwilted, flail-chopped silages made with or without an additive (sodium nitrite and hexamethylene tetramine) were compared with wilted, round-bale silage. The dry matter (DM) concentration of round bale silage (460 g/kg) was higher than that of flail silage (214 g/kg) and this restricted fermentation and N solublisation. When fed to growing cattle, intake (P<0.01), live-weight (LW) gain (P<0.001) and LW gain to feed ratio (P<0.05) were greater for round-bale silage than for flail silage. In Experiment 2, flail-harvested silage was compared with wilted, precision-chopped and round-bale silages conserved either without or with pre-slicing immediately before baling. The DM concentration of flail, precision-chopped and round-bale silages were 163, 334 and 468 g/kg, respectively. Fermentation in flail silage was more extensive than in precision-chopped and particularly round-bale silages, but insoluble-N concentration was unaffected. Round-bale silage was more digestible (P<0.05) than flail or precision-chopped silages. Voluntary intake was higher for steers fed round-bale silages compared to flail silage (P<0.05), while intake of steers fed precision-chopped silage was intermediate (P>0.05). Steers fed round-bale silages had higher LW gain (1.0 kg/day) than those fed flail (0.7 kg/day) or precision-chopped silage (0.8 kg/day; P<0.05). Efficiency of utilization of DM for LW gain was similar for all silages. Pre-slicing at baling had no effect on animal performance. It is concluded that the increased performance by cattle offered silages made by the wilted round-bale system was largely due to higher voluntary intake.
  • Effect of autumn/spring nitrogen application date and level on dry matter production and nitrogen efficiency in perennial ryegrass swards

    O'Donovan, Michael; Delaby, L; Stakelum, G; Dillon, Pat (Teagasc, 2004)
    The influence of autumn/spring N-application date and level on grass dry matter (DM) production in spring and on N uptake, recovery and efficiency were examined over 3 years (1998, 1999 and 2000, identified as Year 1, 2 and 3, respectively). Seven N-application dates were investigated in years 2 and 3 while four application dates were investigated in Year 1. The application dates were 21 October (T1), 11 November (T2), 2 December (T3), 23 December (T4), 12 January (T5), 3 February (T6) and 23 February (T7). Three N-application rates (kg N/ha) were used: 30 (N30), 60 (N60) and 90 (N90) plus a zero-N control (N0). Herbage DM yields were determined on: 18 March (H1) and 8 April (H2). Two herbage masses (HM) (40 mm above ground level) at initial Napplication date were investigated: a high HM (HHM) of 500 kg DM/ha and a low HM (LHM) of 100 kg DM/ha. The HM at initial N-application date in Year 1 was HHM, in Year 2 LHM and in Year 3 both HHM and LHM. There was a significant effect of Year (P<0.001), HM (P<0.001), N-application date (P<0.001) and N level (P<0.001) on DM production at both H1 and H2. At H1 there was a significant interaction between N-application date and level for DM production. N-application date had a significant (P<0.001) effect on N recovery at both H1 and H2. The highest N recovery rate at the two harvest dates was at T5, while the lowest was at T1 and T2. At H1 and H2 there was a significant effect (P<0.001) of application date on response to applied N. The responses were 7.5, 8.0, 8.3, 12.0, 15.7, 7.3 and 5.6 (kg DM/kg N) (s.e. 1.88) for T1 to T7,respectively, at H1, while the corresponding values at H2 were 10.3, 8.7, 6.1, 15.2, 17.6,11.4 and 15.1 (s.e. 1.88). At H2 the response to applied N was 15.6, 11.5 and 9.1 (kg DM/kg N) for N30, N60 and N90, respectively (P<0.05). Regression analysis indicated that highest DM production was achieved with T5 for both H1 and H2 harvest dates, while the lowest responses were associated with T1, T2 and T3 application dates.
  • The effect of herbage mass and allowance on herbage intake, diet composition and ingestive behaviour of dairy cows

    Stakelum, G; Dillon, Pat (Teagasc, 2004)
    An experiment was conducted to examine the effects of herbage mass [HM, based on regrowth intervals of 35 (T) and 21 (S) days] and herbage allowance [HA, 20.2 (H) and 12.7 (L) kg organic matter (OM)/cow] on herbage OM intake (OMI), dietary composition and ingestive behaviour of dairy cows. Four groups of three cows each were used in a 4 × 4 greco-latin square design along with four oesophageal-fistulated cows. The treatment periods were 7 days and the squares (SQ) were repeated three times in a balanced way. The experiment was conducted from 11 April to 3 July 1986. The HM (organic matter) above 3 cm was 3064, 3472 and 3515 kg/ha for T and 2395, 1113 and 2396 kg/ha (s.e. 94) for S, for SQ 1 to 3, respectively. Organic matter digestibility (OMD) was 842, 799 and 778 g/kg for T, and 851, 842 and 804 g/kg for S (s.e. 0.9), for SQ 1 to 3, respectively. Sward height (cm) after grazing was 8.5 and 7.6 for T and S, and 9.6 and 6.5 for H and L (s.e. 0.18), respectively. OMI was 15.2, 14.8 and 15.2 kg for TH, 12.3, 11.9 and 10.7 kg for TL, 15.8, 14.8 and 14.5 kg for SH and 11.9, 11.1 and 11.2kg for SL (s.e. 0.24), for SQ 1 to 3, respectively. The OMD of the diet was closely related to proportion of live leaf in the diet and sward OMD. Average biting rate increased with decreasing HM (R2 0.65). Grazing time was 8.93, 9.11 and 9.06 h for TH, 8.13, 7.96 and 7.91 h for TL, 8.96, 9.59 and 9.29 h for SH and 8.56, 9.36 and 8.52 h for SL (s.e. 0.155), for SQ 1 to 3, respectively. Multiple regression analysis showed that OMI was significantly related to HM (+0.48 kg/t), OMD of the sward (+0.18 kg per 10 g/kg) and pre-experimental milk yield (+0.37 kg/kg) (R2 0.89). The increase in OMI with potential milk yield, as indicated by pre-experimental yield, accounted for 0.80 of the supplementary energy requirements.
  • Genetic relationships among linear type traits, milk yield, body weight, fertility and somatic cell count in primiparous dairy cows

    Berry, Donagh P.; Buckley, Frank; Dillon, Pat; Evans, Ross D; Veerkamp, R. F. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    Phenotypic and genetic (co)variances among type traits, milk yield, body weight, fertility and somatic cell count were estimated. The data analysed included 3,058 primiparous spring-calving Holstein-Friesian cows from 80 farms throughout the south of Ireland. Heritability estimates for the type traits varied from 0.11 to 0.43. Genetic correlations among some type traits were very strong and may indicate the possibility of reducing the number of traits assessed on each animal; the genetic correlation between angularity and body condition score was –0.84. Genetic correlations between all type traits (except body condition score, udder depth and teat length) and milk yield were positive and ranged from 0.08 to 0.69. The possibility of selecting for body weight may be achievable within a national progeny-testing programme using type traits within a selection index. Moderate to strong genetic correlations existed between some type traits and the various fertility measures and somatic cell count indicating the opportunity of indirect selection for improved fertility and health of animals using type traits within a selection index; however, the standard errors of some of the genetic correlations were large and should thus be treated with caution. Genetically taller, wider, deeper, more angular cows with tighter, stronger, shallower udders were predisposed to have inferior pregnancy rates to first service and require more services.
  • A note on the effects of paddock size on the white clover content of swards grazed by sheep

    de Wolf, P.; Schulte, Rogier P.; Lantinga, E. A. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
    The maintenance of a high white clover content in mixed swards under sheep grazing has been a challenge to date. This paper presents the results of an experiment in which the effect of the length of a grazing period on the botanical composition of a mixed sward was studied. Paddocks ranging in size from 0.014 to 0.133 ha were rotationally grazed by a flock of seven dry ewes. Consequently, grazing periods ranged from 1 to about 8 days. On all paddocks, the proportion of perennial ryegrass declined progressively during the grazing season, regardless of paddock size. The proportions of both white clover and creeping bentgrass content increased on all paddocks during the same period. For white clover, the size of the increase was negatively related to paddock size, whereas a positive relationship was found between the paddock size and the magnitude of the increase in creeping bentgrass. This suggests that the proportion of white clover may be increased under sheep grazing by implementation of strip-grazing.