A partially balanced change-over design experiment involving 192 beef steers, which were initially 14 months old and 415 kg live weight, was carried out to determine the intakes of 136 silages from commercial farms in Northern Ireland. Each silage was offered ad libitum as the sole food to 10 animals, with eight silages offered in each of 17 periods over 2 years. A standard grass hay was offered to 16 animals in each period to enable period effects on intake to be removed. Detailed chemical and biological compositions of the silages were also determined. The ranges for pH and dry matter (DM), crude protein, ammonia-nitrogen and apparent digestible organic matter fin vivo) concentrations in the silages and silage dry DM intakes were 3-50 to 5-49 (s.d. 0-396); 155 to 413 (s.d. 43-1) g/kg; 79 to 212 (s.d. 24-4) g/kg DM; 45 to 384 (s.d. 63-2) g/kg total nitrogen; 528 to 769 (s.d. 58) g/kg DM and 4-3 to 10-9 (s.d. 1-13) kg/day respectively. Relationships between intake and individual parameters or groups of parameters have been developed using simple and multiple linear regression analysis and partial least-squares analyses. Silage intake was closely related to factors which influence the extent of digestion and rate of passage of the material through the animal, as indicated by the strong relationships (R 2 of regressions = 0-28 to 0-50) with in vivo apparent digestibility and rumen degradability and the concentrations of the fibre and nitrogen factors. Intake was poorly correlated with factors such as pH, total acidity, buffering capacity and the concentrations of lactic, acetic and butyric acids (R 2 of regressions = zero to 0-11). Near infrared reflectance spectrometry (NIRS) provided the best fit relationship with intake (R 2 of relationship = 0-90). The results also indicate that the intake potential of silages can be directly predicted with a high degree of accuracy from the NIRS of both dried and undried samples of silage, provided the appropriate sample preparation and scanning methods are used.

It has been suggested that United Kingdom recommendations for feeding the neonatal calf (,500 g milk replacer (MR)/day; ,200-230 g CP/kg milk powder) are inadequate to sustain optimal growth rates in early life. The current study was undertaken with 153 high genetic merit, male and female Holstein-Friesian calves (PIN 2000 5 £48) born between September and March, with heifers reared and bred to calve at 24 months of age. Calves were allocated to one of four pre-weaning dietary treatments arranged in a 2 MR feeding level (5 v. 10 l/day) 3 2 MR protein content (210 v. 270 g CP/kg dry matter (DM)) factorial design. MR was reconstituted at a rate of 120 g/l of water, throughout, and was offered via computerised automated milk feeders. Calves were introduced to pre-weaning diets at 5 days of age and weaned at day 56. During the first 56 days of life, calves offered 10 l MR/day had significantly higher liveweight gains ( P , 0.001) than calves fed 5 l MR/day. No significant differences in liveweight gain were found between calves fed 210 g CP/kg DM MR and those fed 270 g CP/kg DM MR from birth to day 56. Differences in live weight and body size due to feeding level disappeared by day 90. Neither MR feeding level nor MR CP content affected age at first service or age at successful service, and with no milk production effects, the results indicate no post-weaning benefits of increased nutrition during the milk-feeding period in dairy heifers.

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 < 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 < 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 < 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 < 0·05) dressing proportion than the other genotypes. Carcass conformation classification (assessed on a five-point scale) was higher (P < 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 < 0·05). Within the Blackface cross lambs, BXB and BLXB lambs had a lower conformation classification (P < 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 < 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 < 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 < 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 < 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 < 0·05), b* (P < 0·001), C* (P < 0·001) and H0 (P < 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 < 0·05) than the other genotypes.

The aim of this study was to evaluate the effects of age and breed on the reproductive performance and lamb output of crossbred hill ewes relative to purebred Scottish Blackface (BF). BF ewes were compared alongside Swaledale (SW) 3 BF, North Country Cheviot (CH) 3 BF, Lleyn (LL) 3 BF and Texel (T) 3 BF ewes on six commercial hill farms across Northern Ireland, on which all the ewes were born and reared. Ewes were mated to a range of sire breeds, balanced across breeds, for up to five successive breeding seasons. Mature live weight of adult BF, SW 3 BF, CH 3 BF, LL 3 BF and T 3 BF ewes was 52.8, 54.9, 60.3, 55.6 and 58.6 kg ( P , 0.001), respectively. Compared with the pure BF, the number of lambs born per ewe lambed was higher with LL 3 BF and SW 3 BF ( P , 0.05), whereas the number of lambs weaned per ewe lambed was greater for LL 3 BF and T 3 BF ( P , 0.01). Total litter weight at birth of all the crossbred ewes was heavier ( P , 0.01) than the pure BF, except in primiparous 2-year-old ewes. Lambs born to CH 3 BF and T 3 BF dams were 0.24 to 0.35 kg heavier at birth ( P , 0.01) than the other ewe breeds, whereas lambs born to CH 3 BF, LL 3 BF and T 3 BF dams were, on average, 1.7, 1.3 and 1.5 kg, respectively, heavier ( P , 0.01) at weaning than those from BF dams due to their higher ( P , 0.05) average daily gain. Compared with the pure BF, total weaned lamb output per ewe lambed was 3.7, 4.8, 6.7 and 5.4 kg heavier ( P , 0.05) for SW 3 BF, CH 3 BF, LL 3 BF and T 3 BF, respectively. However, as a result of the heavier live weight of the crossbred ewes, production efficiency (lamb output per kilogram live weight (W) and lamb output per kilogram metabolic live weight (W 0.75 )) was higher ( P , 0.001) for LL 3 BF ewes only. For all ewe breeds, litter size at birth per ewe lambed, total lamb birth weight per ewe lambed and litter size at weaning increased ( P , 0.001) with age up to 5 years, but decreased in 6-year-old ewes. Average lamb weaning weight and total weaned lamb output per ewe lambed increased ( P , 0.001) with age up to 4 years . Production efficiency of the 6-year-old ewes was lower ( P , 0.01) than the younger ewes. This study shows that adopting a flock replacement policy based on crossing BF ewes with LL, SW, T and CH sires can lead to significant improvements in the productivity of hill flocks.Keywords: crossbreeding, hill flocks, prolificacy, lamb output ImplicationsThe results of this study showed that adopting a flock replacement policy based on crossbreeding Blackface (BF) ewes with Lleyn, Swaledale, Texel (T) or Cheviot (CH) sires can increase productivity of hill flocks compared with pure BF replacements. This is achieved mainly through the increased litter size of the crossbred ewes. While improvements in lamb performance were noted for CH and T-sired ewes, their heavier body weight limits the potential to increase biological efficiency and lamb output per hectare. Assessment of the longevity and lifetime output of these more prolific breed types under hill conditions is, however, essen...

The objective of this study was to determine the effects of plane of nutrition during early and mid-pregnancy on the performance of mature ewes and their offspring. From day 0 to day 39 post mating (early pregnancy, EP), 82 multiparous ewes were fed to provide either 60% (low, L), 100% (medium, M) or 200% (high, H) of predicted metabolisable energy (ME) requirements for maintenance, following a synchronised mating. From day 40 to day 90 (mid-pregnancy, MP), ewes were provided with either 80% (M) or 140% (H) of ME requirements. After 90 days of gestation, all ewes were fed to meet requirements for late pregnancy. During EP, mean live weight (LW) and body condition score (BCS) change of ewes were 26.3, 20.8 and 16.0 kg and 20.02, 10.10 and 10.22 units in the L-, M-and H-EP treatments, respectively. During MP, mean LW and BCS change were 20.8 and 14.9 kg and 20.09 and 10.09 units in the M-and H-MP treatments, respectively (P , 0.001). Treatments had no effect (P . 0.05) on conception rate, although there tended to be an inverse relationship (P 5 0.085) between plane of nutrition in EP and plasma progesterone concentrations at day 42 of gestation. EP nutrition influenced foetal development with lambs from ewes offered diet L-EP being smaller (P , 0.01) at day 56 than M-or H-EP lambs. However, at parturition L-EP lambs were heavier (P , 0.05) and tended to have higher (P 5 0.056) immunoglobulin status 24 h after birth. Mortality rates at weaning were reduced (P , 0.05) for lambs born from ewes offered diet L-EP compared with M-or H-EP lambs. Diet M during mid-pregnancy resulted in larger (P , 0.05) foetuses at day 80 of gestation. At parturition, these lambs had longer head and crown-rump lengths than H-MP lambs (P , 0.05). Lambs born to ewes offered diet M-MP tended to progress faster to attempting to suckle than H-MP lambs (P 5 0.089). There was an interaction between plane of nutrition in early and mid-pregnancy, whereby the highest number of lambs weaned was a result of diet L-EP followed by diet M-MP. These results indicate that in adult ewes, temporary nutrient restriction during early pregnancy results in better lamb survival; and mild nutrient restriction in mid-pregnancy tends to improve neonatal behaviour and results in lambs with longer skeletal size.