Friesian Steers Research Articles

Effects of castration age, dietary protein level and lysine/methionine ratio on animal performance, carcass and meat quality of Friesian steers intensively reared

The effects of castration age, dietary protein level and the dietary lysine/methionine (lys/met) ratio on animal performance, carcass characteristics and meat quality were studied in 64 intensively reared Friesian steers. Animals underwent castration procedures at 15 days old or at 5 months old. Dietary treatments started at 90 days old, with eight animals from each castration age randomly allocated to each treatment: 14.6% v. 16.8% CP (DM basis), and 3.0 v. 3.4 lys/met, on a 2×2×2 design. The recommended ratio of 3.0 was reached with supplementation of protected methionine. Steers were slaughtered at 443.5±26.2 kg live weight when they reached 12 months old approximately. Average daily gain, cold carcass weight or carcass classification were not affected by any studied effect. Muscle moisture (P=0.024), C18:2n-6 percentage (P=0.047), polyunsaturated fatty acid/saturated fatty acid (P=0.049) and n-6/n-3 (P=0.003) were higher in late castrated animals. Both high levels of dietary protein (P=0.008) and lys/met ratio (P=0.048) increased the percentage of muscle in the carcass. A level of 16.8% of CP in the diet also increased the percentage of monounsaturated fatty acids in the intramuscular fat (P=0.032), whereas a ratio lys/met of 3.4 decreased the percentage of saturated fatty acids (P=0.028). Thus, it is recommended using diets with a high protein level (16.8%) and a high lys/met ratio (3.4) in animals slaughtered at a young age, in order to obtain carcasses with high muscle content without negatively affecting productive traits or intramuscular fat composition.

Effect of Harvesting Gliricidia Sepium at Different Cutting Frequencies on Quantity and Quality of Herbage Biomass for Dairy Cattle Nutrition.

Herbage quantity and quality response of Gliricidia sepium to pruning intervals (1.0 to 6.0 months) was evaluated. Chemical composition of coppice re-growth was estimated and herbage was incubated in three rumen fistulated Friesian steers for 3, 6, 12, 24, 48, 72, 96 and 120 h. Herbage dry matter yield tended to follow linear response (P= 0.0689) with increasing coppice re-growth maturity and ranged between 36.2 tones/ha/year to 49.1 tones/ha/year. Protein content (291 g/ kg DM to 220 g/kg DM) decreased following a quadratic trend. However, fibre content increased following a curvilinear trend as herbage matured but levels of lignification increased linearly with delayed harvesting. Additionally, fraction ‘b’ of dry matter degradability (548 to 716 g/kg DM) decreased linearly with herbage maturity. Herbage potential degradability (a+b) (926 to 785 g/kg CP) was indicative of high protein solubility and rumen degradable protein (RDP) decreased with increasing maturity. Consequently, microbial protein synthesis and net energy of lactation (NEL) decreased linearly while rumen undegradable protein (RUP) and digestible undegradable protein (DUP) increased linearly with increasing herbage maturity. These results are interpreted to mean that G. sepium herbage quantity and quality is influenced by pruning management.

Initial Body Condition Score at the Fattening Affects on the Behavioural and Physiological Responses of Holstein Friesian Steers under Heat Stress

Initial Body Condition Score at the Fattening Affects on the Behavioural and Physiological Responses of Holstein Friesian Steers under Heat Stress

Two drying methods of bovine faeces for estimating n-alkane concentration, intake and digestibility: A comparison

An experiment was completed to evaluate effects of two drying methods applied to faecal and herbage samples on estimation of n-alkane concentration and the calculated dry matter (DM) intake, faecal output (FO) and apparent in vivo DM digestibility (DMD). Four Holstein–Friesian steers (182±12.1kg initial body weight) housed in individual pens were fed at 8:30 and 16:30h with ryegrass (Lolium perenne L.) hay for 18d. Refusals were removed and weighed every day at 8:30h before morning feeding. From days 9 to 18, the steers were dosed twice a day at feeding time, with cellucotton stoppers containing C32 (88.49mg/pellet) and C36 (87.12mg/pellet). During the last 5d of dosing, total collection of faeces was completed using harnesses. For the n-alkane analysis, faecal (n=64) and offered hay (n=4) samples were subdivided into two subsamples and prepared for two alternative drying methods: oven-drying at 60°C (OD) or freeze-drying (FD). The n-alkane profiles of the offered and refused hay oven-dried at 60°C did not differ. In offered hay subsamples, concentrations of n-alkanes were not affected by drying method. In faecal subsamples, drying method affected (P<0.05) concentrations of all n-alkanes, except for C23, C25 and C35, as well as the ratios C32:C31 and C32:C33. There were no differences between estimated and measured values when DM intake and apparent in vivo DMD were estimated based on the ratio C32:C33. In contrast, when the ratio C32:C31 was used, estimated values either differed (P<0.02) or tended to differ (P<00.09) from measured values for OD and FD subsamples, respectively. Estimates of FO from subsamples OD and FD did not differ from measured values. Faecal recovery increased with increasing carbon-chain length in both drying methods. Results show that oven-drying at 60°C could replace freeze-drying for sample dehydration to estimate DM intake and apparent in vivo DMD when ratio C32:C33 was used. However, due to the low number of replicates, further studies should be conducted before use of C32:C33 ratio in oven-dried samples can be recommended.

Ruminal protozoal contribution to the duodenal flow of fatty acids following feeding of steers on forages differing in chloroplast content

Ruminant products are criticised for their SFA content relative to PUFA, although n-6:n-3 PUFA is desirable for human health (<4). Rumen protozoa are rich in unsaturated fatty acids due to engulfment of PUFA-rich chloroplasts. Increasing the chloroplast content of rumen protozoa offers a potentially novel approach to enhance PUFA flow to the duodenum and subsequent incorporation into meat and milk. We evaluated protozoal contribution to duodenal n-3 PUFA flow due to intracellular chloroplast content. A total of six Holstein×Friesian steers were fed, in a two-period changeover design, either straw:concentrate (S:C, 60:40; DM basis; S:C, low chloroplast) or fresh perennial ryegrass (PRG; high chloroplast). Following 12d adaptation to diet, ruminal protozoal and whole duodenal samples were obtained. N and fatty acid content of whole duodenum and rumen protozoal samples were assessed and protozoal 18S rDNA quantitative PCR performed, enabling calculation of protozoal N flow. The ratio of individual fatty acids:N in rumen protozoal samples was calculated to obtain protozoal fatty acid flows. Based on total fatty acid flow, contribution (%) of protozoa to individual fatty acid flows was calculated. Protozoal fatty acid data and microscopical observations revealed that protozoa were enriched with 18:3n-3 following PRG feeding, compared with the S:C diet, due to increased intracellular chloroplast content. However, duodenal protozoal 18S rDNA concentration post PRG feeding was low, indicating rumen retention of the protozoa. Nutrition influences the 18:3n-3 content of protozoa; the challenge is to increase protozoal flow to the small intestine, while maintaining sustainable rumen densities.

Finishing cattle at pasture at 30 months of age or indoors at 25 months of age: Effects on selected carcass and meat quality characteristics

To examine the effect of a modification of a typically Irish dairy calf-to-beef production system, Charolais×Friesian steers were offered a finishing ration of grass silage ad libitum and 5.6kg concentrates daily for 174days prior to slaughter at 25months of age or grass silage ad libitum for 174days, followed by pasture for 167days and slaughter at 30months of age. Finishing at pasture increased carcass weight (376 vs. 342kg) but did not affect intra-muscular lipid concentration (28 vs. 24g/kg). Finishing at pasture decreased Longissimus thoracis et lumborum lightness (35.6 vs. 36.9) and increased shear force of muscle at 2 (8.54 vs 4.32) and 7days (5.21 vs 3.64kg) post-mortem but not at 14days post-mortem (4.45 vs. 3.42kg). Finishing at pasture did not affect the sensory characteristics of tenderness, juiciness, firmness or chewiness and tended (P<0.1) to decrease texture and acceptability. It is concluded that modification of this beef production system as described, had minor effects on beef quality which are unlikely to be of commercial significance.

As yet uncultured bacteria phylogenetically classified as Prevotella, Lachnospiraceae incertae sedis and unclassified Bacteroidales, Clostridiales and Ruminococcaceae may play a predominant role in ruminal biohydrogenation

Microbial biohydrogenation of dietary poly-unsaturated fatty acids (PUFA) to saturated fatty acids (SFA) in the rumen results in the high ratio of SFA/PUFA in ruminant products, such as meat and milk. In vitro, Butyrivibrio proteoclasticus-related bacteria extensively biohydrogenate PUFA to SFA, yet their contribution in the rumen has not been confirmed. The aim of this study was to evaluate the role of Butyrivibrio proteoclasticus group bacteria in ruminal biohydrogenation and to assess the possible role of other bacteria. Fish oil at 0%, 1.5% and 3% dry matter intake was fed to eight Holstein × Friesian steers, in order to elicit changes in the extent of PUFA biohydrogenation. Fatty acid and B. proteoclasticus group 16S rRNA concentrations in rumen digesta were determined. Correlation between digesta 18:0 concentration and B. proteoclasticus group 16S rRNA concentration was low. Terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis (DGGE) coupled with multivariate statistics revealed that many terminal restriction fragments (T-RFs) and DGGE bands were linked to cis-9, trans-11 conjugated linoleic acid (CLA), 18:1 trans-11 and 18:0 ruminal concentrations. MiCA T-RF predictive identification software showed that these linked T-RFs were likely to originate from as yet uncultured bacteria classified as Prevotella, Lachnospiraceae incertae sedis, and unclassified Bacteroidales, Clostridiales and Ruminococcaceae. Sequencing of linked DGGE bands also revealed that as yet uncultured bacteria classified as Prevotella, Anaerovoax (member of the Lachnospiraceae incertae sedis family), and unclassified Clostridiales and Ruminococcaceae may play a role in biohydrogenation.

Rumen protozoa are rich in polyunsaturated fatty acids due to the ingestion of chloroplasts

Within this study, we investigated whether the polyunsaturated fatty acids (PUFA)-rich nature of rumen protozoa is a consequence of ingestion of PUFA-rich chloroplasts. Four Hereford x Friesian steers were offered hay [low 18:3 (n-3) and low chlorophyll concentration] followed by freshly cut perennial ryegrass [high 18:3 (n-3) and high chlorophyll concentration] for 16 days. On the 14th and 16th days, rumen protozoa as well as attached and planktonic bacteria were fractionated 1 h before (-1 h), 2 and 6 h postfeeding, and their fatty acid concentrations determined. Protozoa fractionated from fresh grass-fed steers were richer (P<0.05) in PUFA, except conjugated linoleic acid, for all time points compared with those from hay-fed steers. Protozoal density was higher (P<0.05) for grass compared with hay. Entodinomorphid abundance was 3.4 times higher on fresh grass (P<0.01) compared with hay. Confocal microscopy and transmission electron microscopy confirmed that Epidinium spp. were commonly saturated with intracellular cytoplasmic chloroplasts. These data suggest that engulfment of chloroplasts is a major contributor to the high 18:3 (n-3) concentration of protozoa.

Effect of lipid-rich plant extract on the fatty acids composition and meat quality of Charolais × Friesian steers

Nutrition has a major impact on the fatty acid composition of beef, despite high levels of biohydrogenation of dietary polyunsaturated fatty acids (PUFA) in the rumen (Scollan et al., 2006). The latter may be ameliorated by feeding rumen-protected lipid. Grass relative to concentrate feeding results in beef characterised by a higher content of n-3 PUFA and excellent colour shelf life. This study investigated the effects of including a PUFA-rich lucerne-based plant extract (PX) on the fatty acid composition and meat quality in beef.

Effects of supplementary concentrate level in winter, and subsequent finishing on pasture or indoors, on performance and carcass traits of Holstein–Friesian, Aberdeen Angus × Holstein–Friesian and Belgian Blue × Holstein–Friesian steers

Pure bred Holstein–Friesian (FR) and beef breed × FR male calves are used for beef production in Ireland. Beef breeds used for crossbreeding on FR cows include Aberdeen Angus (AA) and Belgian Blue (BB) which represent extremes in terms of maturity. The objective of this study was to compare spring-born steers of FR, AA and BB breed types, offered two feeding levels in their second winter, and subsequently finished on pasture or on a high concentrate diet indoors. Seventy-two steers (24 per breed type) were managed together to the end of their second grazing season. They were then blocked on weight within breed type and assigned to a 3 (FR, AA and BB breed types) × 2 (winter feeding levels) × 2 (finishing systems) factorial experiment. The two winter feeding levels were grass silage ad libitum plus mean daily concentrate levels of 0.91 (L) or 4.0 (H) kg dry matter for 113 days. The two finishing systems were pasture or concentrates ad libitum for a mean period of 94 days. Mean slaughter and carcass weights for FR, AA and BB were 634, 644 and 642 (s.e. 8.1), and 313, 326 and 340 (s.e. 4.7) kg, respectively. Other than bone proportion which was lower for AA, there were few differences in ribs joint composition or in m. longissimus chemical composition between FR and AA. BB had less fat and more muscle in the ribs joint, and more moisture and protein, and less lipid in m. longissimus than both FR and AA. Compared with L, the H winter feeding level increased slaughter weight and carcass weight by 24 and 15 kg, respectively. Indoor finished animals were 63 kg live weight and 39 kg carcass weight heavier than those finished at pasture. They also had more fat and less muscle and bone in the ribs joint and more lipid and less moisture in m. longissimus. It is concluded that except for BB finished at pasture all carcasses were commercially acceptable. Despite the excellent finishing performance on concentrates, this system is not profitable at current concentrate and beef prices.

Intake, rumen fermentation, degradability and digestion kinetics in beef cattle offered autumn grass herbage differing in regrowth interval

AbstractThe effects of a 10‐d increase in regrowth interval (35 and 45 d) of a predominantly perennial ryegrass sward harvested in two periods in the autumn in Ireland on feed intake, rumen fermentation, in situ degradability and rumen digesta kinetics was examined using six ruminally cannulated Holstein–Friesian steers in three replicates of a 2 × 2 crossover design. The longer regrowth interval had a higher grass dry‐matter (DM) yield of herbage by 615 kg DM ha−1 and a lower crude protein (CP) concentration of herbage by 27 g kg−1 DM. There was no effect of regrowth interval on DM intake, rumen pH, total volatile fatty acid concentration or the molar proportions of acetate, propionate or butyrate in the rumen but the concentration of rumen ammonia (NH3‐N) was lower on the longer regrowth interval. The longer regrowth interval had a lower apparent total tract digestibility of DM, organic matter (OM), N and neutral‐detergent fibre (NDF). There was no effect of regrowth interval on the in situ degradability of DM, OM, N or NDF. The passage rates (kp) of DM and OM were higher while the rate of digestion (kd) of DM and NDF was lower with the longer regrowth interval. The results indicated that, although increasing the regrowth interval by 10 d in autumn reduced the apparent digestibility of the grass herbage, there was no adverse effect on DM intake, rumen fermentation pattern or in situ rumen degradability. The reduction in rumen NH3‐N concentrations, reflecting the lower herbage CP concentration in herbage for the longer regrowth interval, may potentially reduce nitrogen excretion to the environment.

Nitrogen, Phosphorus and Potassium Losses in a Grazing System with Different Stocking Rates in a Volcanic Soil

A B S T R A C T In Chile there is little information on nutrient losses in livestock systems. The experiment was carried out between 2004 and 2006. Two stocking rates (3.5 and 5.0 steers ha -1 ) were tested under rotational grazing with Black and White Friesian steers on a permanent pasture (67.5 kg N and 40 kg P ha -1 yr -1 ). To quantify surface runoff losses (N, P, K), three surface lysimeters (5 x 5 m) per treatment were established. N and K leaching losses were estimated with ceramic cups. Runoff and leachate samples were individually analyzed for available and total N, reactive (RP) and total P, and K. Dissolved organic N (DON) and organic P (OP) were estimated as the difference between total and available forms. The stocking rate did not increase total N, P and K losses (P > 0.05). Losses in surface runoff were < 0.5 kg N, < 0.05 kg P and < 0.6 kg K ha -1 yr -1 , respectively, due to the low amount of runoff measured. Nitrogen leaching losses were high (11 up to 71 kg ha -1 yr -1 ) and K leaching losses were low (3 to 5 kg ha -1 yr -1 ). Nitrogen in runoff was mainly lost as DON (50%). Nitrogen leaching losses were mainly as nitrate (70%). Phosphorus was lost as RP (70%). Thus, stocking rates of 5.0 steers ha -1 are plausible, but fertilizer application should be avoided in rainfall periods during the year to reduce incidental nutrient losses.

Intake, digestibility and rumen characteristics in cattle offered whole-crop wheat or barley silages of contrasting grain to straw ratios

The effects of varying the grain (G) to straw (S) ratio (G:S) of whole-crop wheat and barley silages on intake and digestibility and whole-crop barley silage on rumen fermentation characteristics were examined in two parallel studies. For the intake and digestibility study, eight Aberdeen Angus cross-bred steers (mean bodyweight 407 kg (S.D. 24.2)) were used in two (barley and wheat) 4 × 4 Latin Square designed experiments. The dietary treatments were four G:S ratios: 0:100, 30:70, 60:40 and 90:10. Intake of grain linearly increased ( P<0.001) while that of straw decreased ( P<0.001) as the ratio of G:S increased for both cereals. No effect ( P>0.05) was observed in total dry matter (DM) intake (DMI) or in DMI per kg liveweight. There was a positive linear ( P<0.001) effect on the digestibility of the DM and organic matter (OM) and a negative linear effect on neutral detergent fibre (aNDFom) digestibility ( P<0.01) as the G:S ratio increased for both cereals. Both a positive linear ( P<0.05) and quadratic ( P<0.01) effect were observed for the G:S ratio on nitrogen (N) digestibility of barley and a corresponding positive linear increase ( P<0.01) for wheat. A negative linear effect was found for digestibility of starch ( P<0.01) and a positive linear effect for faecal grain content ( P<0.01) with increasing G:S ratio. Four Holstein–Friesian steers (mean bodyweight 659 kg (S.D. 56.9)) fitted with rumen cannulae were used in the rumen study. A negative linear effect of G:S ratio was found on rumen pH ( P<0.001) while a positive linear effect was found on rumen ammonia ( P<0.001) and total volatile fatty acid (VFA) concentration ( P<0.01) with increasing G:S ratio. A negative linear effect ( P<0.01) was found on the molar proportion of acetic acid. However, this decrease was offset by linear increases in the molar proportions of iso- and n-butyric acid, iso- ( P<0.01) and n- ( P<0.05) valeric acid, and to a lesser extent in propionic acid ( P<0.01). No effect of treatment was found on rumen pool sizes of DM or its constituents. A positive linear effect ( P<0.01) was found on the effective degradability (ED) of the DM, OM, N and starch while it was found to be negative in aNDFom ( P<0.05). No effect ( P>0.05) was found on the fractional clearance rates of DM, OM, aNDFom or starch or on liquid passage rate. It is concluded that increasing the G:S ratio in whole-crop wheat or barley silage linearly increased the intake of digestible nutrients for both wheat and barley and increasing the G:S ratio for whole-crop barley increased the concentration of fermentation products (total VFA, ammonia and the molar proportions of the VFAs, except acetic acid) in the rumen.

Fish Oil Increases the Duodenal Flow of Long Chain Polyunsaturated Fatty Acids andtrans-11 18:1 and Decreases 18:0 in Steers via Changes in the Rumen Bacterial Community ,

Ruminant fat is rich in SFA, partly due to the biohydrogenation of dietary PUFA to SFA in the rumen. This process can be inhibited by the dietary inclusion of fish oil. The only bacteria isolated from the rumen capable of converting PUFA to SFA are closely related to Clostridium proteoclasticum. The aim of this study was to investigate if a correlation could be found in vivo between dietary fish oil inclusions and the composition of the ruminal bacterial community and specifically of C. proteoclasticum. Six Hereford × Friesian steers, prepared with ruminal and duodenal cannulae, received grass silage plus 1 of 3 concentrates resulting in total dietary fish oil contents of 0, 1, or 3% of dry matter. A dual flow marker technique was employed to estimate the relative flow of fatty acids. Steers fed the 3% fish oil diet had 100% increases intrans 18:1 flow, whereas 18:0 flow declined to 39% of steers fed the control diet. 16S ribosomal RNA-based denaturing gradient gel electrophoresis profiles obtained from ruminal digesta showed major changes in the bacterial community within steers fed the 3% fish oil diet. Quantitative PCR indicated only a weak relation between numbers ofC. proteoclasticum and 18:0 flow between treatments and in individual steers (P < 0.05, but the percentage variance accounted for only 22.8) and did not provide unambiguous evidence that numbers ofC. proteoclasticum in the rumen dictate the ratios of SFA:PUFA available for absorption by the animal. Understanding which microbes biohydrogenate PUFA in the rumen is key to developing novel strategies to improve the quality of ruminant products.

Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers fed diets based on different proportions of maize silage and grass silage

Replacing grass silage with maize silage results in a fundamental change in the ratio of structural to non-structural carbohydrates with commensurate changes in rumen fermentation patterns and nutrient utilisation. This study investigated the effects of feeding four forage mixtures, namely grass silage (G); 67 g/100 g grass silage + 33 g/100 g maize silage (GGM); 67 g/100 g maize silage + 33/100 g grass silage (MMG); maize silage (M) to four ruminally and duodenally canulated Holstein Friesian steers. All diets were formulated to be isonitrogenous (22.4 g N/kg DM) using a concentrate mixture. Dietary dry matter (DM) and organic matter (OM) digestibility increased with ascending maize silage inclusion (P < 0.1) whereas starch and neutral detergent fibre digestibility declined (P < 0.05). Ratio of non-glucogenic to glucogenic precursors in the rumen fluid increased with maize silage inclusion (P < 0.01) with a commensurate reduction in rumen pH (P < 0.05). Mean circulating concentrations of insulin were greatest and similar in diets MMG and GGM, lower in diet M and lowest in diet G (P < 0.01). There were no effects of diet on the mean circulating concentration of growth hormone (GH), or the frequency, amplitude and duration of GH pulses, or the mean circulating concentrations of IGF-1. Increasing levels of DM, OM and starch intakes with the substitution of grass silage with maize silage affected overall digestion, nutrient partitioning and subsequent circulating concentrations of insulin.

Intake, rumen fermentation and nutrient flow to the omasum in beef cattle fed grass silage fortified with sucrose and/or supplemented with concentrate

The objective was to determine the relative effects of a specific increase in grass silage sucrose concentration, or a specific supplement of a starch-based concentrate, on rumen fermentation and nutrient supply to the omasum in beef cattle. Four ruminally cannulated Holstein–Friesian steers were fed grass silage only (G), G plus 3 kg concentrates/day (GC), G plus 90 g sucrose/kg dry matter (DM) (GS) and G plus 90 g sucrose/kg DM plus 3 kg concentrates/day (GCS) in a 4 × 4 Latin Square design experiment. Omasal flow was estimated using Co-EDTA, Yb-acetate and indigestible neutral detergent fibre (INDF) as digesta flow markers and purine bases as microbial markers. Concentrate supplementation reduced ( P < 0.01) silage and increased ( P < 0.001) total DM intake whereas sucrose had no effect. There was a sucrose × concentrate interaction ( P < 0.05) for rumen pH whereby addition of sucrose to grass silage alone decreased pH and to grass silage plus concentrate had no effect. Rumen ammonia N ( P < 0.01), total volatile fatty acid (VFA) concentration ( P < 0.05) and the molar proportions of valerate ( P < 0.05) and butyrate ( P < 0.001) increased with concentrate supplementation whereas, sucrose supplementation had no effect on rumen fermentation parameters. Organic matter (OM) intake, omasal OM flow, the quantities of OM apparently (OMAD) and truly digested (OMTD) in the rumen ( P < 0.001) and total tract OM digestibility ( P < 0.01) increased, and apparent and true ruminal OM digestibility decreased ( P < 0.05) with concentrate supplementation. Supplementation with concentrate decreased ( P < 0.05) ruminal neutral detergent fibre (aNDFom) digestibility and increased ( P < 0.05) aNDFom omasal flow. There was a tendency for addition of sucrose to increase ( P < 0.1) ruminal OMAD and OMTD, while there was no effect of sucrose addition on intake or digestion of aNDFom. Concentrate supplementation increased ( P < 0.001) N intake, flows of N, non-ammonia N (NAN), microbial N (MN) ( P < 0.05) and non-ammonia non-microbial N (NANMN) ( P < 0.01) and apparent total tract digestibility of N ( P < 0.01), whereas sucrose reduced ( P < 0.05) N intake and apparent ruminal N digestibility. There was no effect of concentrate or sucrose on N use efficiency or efficiency of microbial protein synthesis. Concentrate supplementation increased ( P < 0.001) plasma β-hydroxybutyrate levels. In comparison to supplementing unwilted, well preserved grass silage of moderate digestibility with 3 kg starch-based concentrate per day, the limited response to the rate of sucrose supplementation employed suggests that increasing the water-soluble carbohydrate (WSC) concentration of grass silage through agronomic and/or ensiling practices will have relatively little effect on intake, rumen digestion or efficiency of microbial N synthesis.

Energy supply patterns for finishing steers: Feed conversion efficiency, components of bodyweight gain and meat quality

The objective was to determine the effect of pre-slaughter growth rate on feed efficiency, components of body growth and on the tenderness of longissimus muscle from steers reared to a common age and carcass weight. Sixty Friesian steers were group-housed and offered grass silage ad libitum and 3.5 kg concentrates per animal daily for 5 months and then 5 kg concentrates and 1 kg grass hay for 1 month before the experiment began. The animals were then weighed and in a randomised block were assigned to one of 5 groups, for slaughter at the beginning of the experiment or to be offered concentrates and hay (900 and 100 g/kg total diet, respectively) to achieve target growths of: 0.72 kg/day continuously for 17 weeks, 0.36 kg/day for the first 8 weeks and 1.08 kg/day for the final 8 weeks (low–high), 1.08 kg/day for the first 8 weeks and 0.36 for the final 8 weeks (high–low) or 0.36 kg/day for the first 2 weeks, 0.72 kg/day during weeks 4 and 14 and 1.08 kg/day for the final 2 weeks (pulse). One week was allowed for transition to the different dietary allowances within each energy supply pattern. The mean age at the beginning and end of the study was 18 and 22.5 months, respectively. After slaughter, the weight of the carcass and kidney + channel fat depot were recorded, the pistola hind quarter was dissected into fat, lean and bone and the tenderness of the m. longissimus thoracis et lumborum (LTM) muscle was measured instrumentally and using a trained taste panel after 2, 7 or 14 days ageing. The pattern of energy supply did not affect carcass weight, fat score or kidney + channel fat weight. The pistola hind quarter from animals offered the low–high energy pattern had a similar composition to the continuously-fed animals but contained more muscle than that from animals offered high–low or pulse energy patterns. After 14 days ageing, LTM from the continuously-fed animals was more tender than that from animals offered the other energy supply patterns but shear force did not differ between supply patterns. The data do not support the hypothesis that pre-slaughter growth rate increases tenderness but suggest that energy supply pattern can influence body composition of finishing cattle.

Phosphorus losses in surface run‐off from grazed permanent pastures on a volcanic soil from Chile

AbstractReactive (RP) and organic phosphorus (OP) losses from grazed paddocks were determined on a volcanic soil during 2004 and 2005. Paddocks were grazed by Holstein Friesian steers (3.5 steers ha−1) and received N (67.5 kg ha−1) and P fertilizer (30 kg P ha−1). Total losses ranged between 4 and 15 g P ha−1 year−1 and were greatly affected by incidental P losses associated with spring P fertilizer application. Reactive P constituted 90% of the total losses on average. Due to the high water infiltration capacity of the soil, run‐off was &lt;1% of total drainage, therefore, phosphorus losses in run‐off were small.

Fatty acid composition of M. Longissimus dorsi from Holstein–Friesian steers of New Zealand and European/American descent and from Belgian Blue × Holstein–Friesian steers, slaughtered at two weights/ages

Our objective was to determine the effect of breed (B) and slaughter age/weight on the fatty acid composition, particularly the conjugated linoleic acid (CLA) concentration of beef. Two strains of a dairy breed [Holstein–Friesian (HF) ( n = 16 steers/strain)] and a late-maturing breed [Belgian Blue × Holstein–Friesian (BB) ( n = 16 steers)] were used. The HF strains were either of New Zealand (NZ) or European–American (EU) descent (selected in a grazed grass or a high concentrate nutritional environment, respectively). Animals were grown from calves to either a light (L; 560 kg) or heavy (H; 630 kg) target slaughter weight. Samples of M. longissimus dorsi were collected post-slaughter, lipids were separated into neutral (NL) and polar (PL) fractions, and fatty acid composition determined by gas-chromatography. The total fatty acid concentration and the concentrations of cis9, trans11 CLA, total CLA, MUFA and SFA in total intramuscular lipids were lower and the P:S ratio higher for BB than NZ or EU which did not differ. These differences largely reflected the changes in NL. The C18 desaturase index was higher for NZ than EU but EU did not differ from BB. Increasing slaughter weight/age increased the total fatty acid concentration and the concentrations cis9, trans11 CLA ( P = 0.06), total CLA ( P = 0.06), trans11 C18:1, MUFA and SFA and the C18 desaturase index and decreased the P:S ratio. The n-6:n-3 PUFA ratio was similar at the lighter slaughter weight/age for the three breeds/strains but increased for NZ and EU with increasing slaughter weight/age but was not affected in BB. It is concluded that the CLA concentration largely reflected muscle fatness but that increasing slaughter weight/age differentially affected the n-6:n-3 PUFA ratio of beef from early and late-maturing cattle.

Effect of repeated regrouping and relocation on behaviour of steers

To investigate the effect of repeated regrouping and relocation (R&R) on behaviour of steers, 72 Holstein–Friesian (14-month-old; 441 ± 3.2 kg) steers were assigned to either control ( n = 30; C) or regrouped ( n = 42; R) treatments and housed six per pen in 12 pens. The R steers were exposed to six R&R over 84 days. New pen cohorts were allowed to stabilise for 14 days and none of the R steers were allowed to share the same pen or pen mates, where or with whom, they were previously housed. Control steers were housed in the same pen with the same pen mates. Each steer was marked on its back with an individual identification code. Twelve cameras were used to observe and record behaviour for each pen allowing observation of all individual steers continuously for a week following each R&R. The following behaviours were recorded for each steer: lying, standing, eating, drinking, head-to-head contact with another animal while not eating, head contact with the body of another animal and bodily contact with none, one, two or three steers. Behaviour was observed by instantaneous scan sampling after each R&R, at 2 min intervals for 2 h on day 1; at further 20 min intervals on days 1 and 2; and at 120 min intervals from day 3 to 7. Where appropriate, the % of time spent in each behaviour was calculated from the data on total counts in each behavioural category. The total count data were analysed by χ 2-statistics for all behavioural categories. Steers were weighed before each R&R. Average daily gain from day 0 to 84 was analysed by ANOVA. During the first 2 h observation period following mixing, R steers displayed a greater ( P < 0.05) % of time standing (following the first to sixth R&R), eating (first to fourth and sixth R&R) and drinking (first, third and fourth R&R) than control steers. In the 20 min observational period, a greater % ( P < 0.05) of time was spent standing, eating and drinking in R than in C steers following each R&R. In the 120 min observation period, R steers spent a greater ( P < 0.05) % of time lying with less body contact behaviours than C steers, and these findings increased in the fourth, fifth and sixth R&R. These data suggest that there was partial adaptation to repeated R&R at the first two R&R followed by complete adaptation at the third and subsequent R&R, with no detrimental effect on animal performance.