Effect of breed and castration on production and carcass traits of male lambs following an intensive finishing period

peer-reviewedThe practice of crossbreeding using a terminal sire and the use of intact rather than castrated animals has the potential to increase the productivity of lambs produced from the hill sheep sector. The objective of this study was to compare the production and carcass characteristics of purebred Scottish Blackface (SB) and Texel cross Scottish Blackface (TXSB) ram and wether lambs fed on a concentrate diet and slaughtered at different ages. Two hundred spring born male lambs (average birth age ±SD 9.53 d) were assigned to a 2 × 2 factorial arrangement with two breeds SB (n=100) and TXSB (n=100)) and two sexes (wether: n=100 and ram: n=100)). Lambs were harvested following a 36 d ad libitum concentrate indoor finishing period. The study was carried out over five harvest batches between October and April. The mean ages of the lambs at harvest (n = 40, 20 TXSB and 20 SB lambs) in October, November, January, March and April were 196, 242, 293, 344 and 385 days, respectively The TXSB lambs were heavier at slaughter than SB lambs (P < 0.001) and ram lambs were heavier at slaughter than wether lambs (P < 0.01). Improved average daily gain (ADG) (P < 0.001), lower feed conversion ratio (FCR) (which was calculated by dividing total feed intake by total weight gain) (P < 0.001) and higher feed intake (P < 0.05) were recorded in TXSB lambs with consistency across the five harvest time points. Rams had greater ADG (P < 0.001) and FCR (P < 0.05) compared to wether lambs and no differences were observed between sexes for feed intake. The TXSB (P < 0.001) lambs had higher (P < 0.001) dressing percentages compared to SB while wether lambs had greater dressing percentages compared to rams. The TXSB lambs had heavier carcass weights (P < 0.001) with higher conformation grades (P < 0.001) and less fat cover (P < 0.001) than SB lambs while ram lambs had heavier (P < 0.001) carcasses than wether lambs. There was greater fat cover on the loin muscles of SB (P < 0.001) and wether (P < 0.001) lambs compared to TXSB and ram lambs, respectively. The results from this study suggest that TXSB lamb’s offer hill sheep farmers a potential strategy for improved lamb production efficiency, while ram lambs offer lamb finishers increased growth rates, higher FCR and produce a more desirable carcass than do wether lambs

Effects of castration and slaughter age on the fatty acid composition of ovine muscle and adipose tissue from two breeds

peer-reviewedFatty acids (g/100 g total fatty acids) in M. longissimus thoracis et lumborum (LTL) and total branched chain fatty acids (μg/g fat) in subcutaneous adipose tissue (SAT) of rams and castrates from Scottish Blackface (SB) or Texel × Scottish Blackface (T × SB) lambs, slaughtered at mean ages of 196, 242, 293, 344 or 385 days were determined. Lambs were fed pasture prior to a 36-day finishing period on a barley/maize-based concentrate ration. The intramuscular fat content (IMF; %) was higher (P < 0.001) in castrates than in rams and in SB compared to T × SB lambs (P < 0.001). The proportions of c9-C18:1 and total monounsaturated fatty acids (MUFA) were higher (P < 0.001) in LTL of castrates than rams. The proportions of C18:2n-6 and total n-6 polyunsaturated fatty acids (PUFA) were lower (P = 0.001) in LTL of castrates compared to rams related to differences in IMF content. The proportions of C14:0, C16:0, c9-C18:1 and total MUFA were higher (P < 0.05), while the proportions of C18:2n-6, C20:4n-6, C20:5n-3, total PUFA, n-6 and n-3 PUFA were lower (P < 0.05), in SB than in T × SB lambs, which was related to differences in IMF content. There was a higher (P < 0.001) proportion of conjugated linoleic acid (CLA) c9,t11-C18:2 in LTL from SB compared to T × SB. The effects of slaughter age on the proportions of fatty acids in LTL did not show a clear trend. The concentration of 4-methylnonanoic acid was higher (P = 0.002) in SAT of rams than castrates, particularly in older lambs. Despite the differences in the muscle fatty acid composition due to gender, slaughter age or breed of lambs, the ratio of n-6/n-3 PUFA (≤3.11) was within the dietary recommendation of <4.0 for human health

Effect of forage to concentrate ratio and duration of feeding on growth and feed conversion efficiency of male lambs

peer-reviewedRations (dry matter basis) for spring born male lambs consisting of concentrates ad libitum (CON), 50:50 (50% concentrate:50% forage) and forage ad libitum (FORG) were evaluated across feeding periods of 3 durations (36 d, 54 d and 72 d). Lambs on CON diets were offered ad libitum access to concentrate along with 400g of fresh weight silage (daily), while 50:50 diets were offered 0.9 kg and 3.0 kg of concentrate and silage, respectively. Lambs on FORG were offered ad libitum access to 25.5% dry matter silage. These rations were fed to 99 spring born male Texel cross Scottish Blackface lambs which were assigned to a 3 × 3 factorial arrangement. Lambs were slaughtered following completion of their respective treatments. Lambs fed CON diets had greater ADG, FCE, and carcass weight (P < 0.001) and carcasses with greater conformation score (P < 0.001) than lambs fed 50:50 or FORG diets. Duration of feeding had no effect on production variables across all three concentrate inclusion levels. It was concluded that the inclusion of concentrates is needed to adequately finish lambs fed indoors. Feeding lamb’s 50:50 diets resulted in modest responses and may be a viable option for finishing lambs or to maintain growth in lambs when the cost of concentrate feed is high relative to the financial return on the lamb meat

Effect of castration and age at slaughter on sensory perception of lamb meat

peer-reviewedThis study assessed the effect of castration and slaughter age (196–385 days old) on sensory quality of lamb meat from two sheep breeds (Scottish Blackface, SB; Texel x Scottish Blackface, TxSB). Results obtained using a trained sensory panel showed small but statistically significant differences due to castration, with rams having higher scores for Intensity of Lamb Aroma, Animal Smell/Farm Smell, Woolly Aroma, Rancid Aroma, Manure/Faecal Aroma, Sweaty Aroma and Off-flavours. SB lamb had higher scores for Intensity of Lamb Aroma, Lamb Flavour, Lamb Aftertaste, Tenderness and Juiciness. Age effects on sensory attributes were not linear and significant age × gender interactions were observed. The number of samples considered “extreme” in undesirable flavour attributes was higher among rams and T × SB animals. The impact of the sensory differences on consumer acceptability of lamb remains to be established

Effect of finishing diet and duration on the sensory quality and volatile profile of lamb meat

peer-reviewedAnimal production factors can affect the sensory quality of lamb meat. The study investigated the effect of diet composition and duration of consumption on the proximate analysis, volatile profile and sensory quality of lamb meat. Ninety-nine male Texel × Scottish Blackface lambs were raised at pasture for 10 months before being assigned in groups of 11 to one of the following treatments: 100% Silage (S) for 36 (S36), 54 (S54) or 72 (S72) days; 50% Silage - 50% Concentrate (SC) for 36 (SC36), 54 (SC54) or 72 (SC72) days; 100% Concentrate (C) for 36 (C36) or 54 (C54) or 72 (C72) days. A trained sensory panel found Intensity of Lamb Aroma, Dry Aftertaste and Astringent Aftertaste to be higher in meat from lambs on the concentrate diet. Discriminant analysis showed that the volatile profile enabled discrimination of lamb based on dietary treatment but the volatile differences were insufficient to impact highly on sensory quality. Muscle from animals in the S54 group had higher Manure/Faecal Aroma and Woolly Aroma than the SC54 and C54 groups, possibly related to higher levels of indole and skatole. Further research is required to establish if these small differences would influence consumer acceptability.The financial support of the Irish Department of Agriculture, Food and the Marine (project 11/SF/310) and of the Teagasc Walsh Fellowship Programme (award 2013058) is gratefully acknowledged

Effect of Alternative Protein Feeds on the Content of Selected Endogenous Bioactive and Flavour-Related Compounds in Chicken Breast Meat

: Currently, soybean meal constitutes the main protein source for poultry production. However, the environmental and social issues related to soybean production are calling for more sustainable protein sources that can offset soybean requirements in animal production. Hermetia illucens larvae and the microalga spirulina (Arthrospira platensis) have proven to be effective alternatives to soybean meal for poultry production. In this study, the effect of 100% replacement of soy with partially defatted Hermetia illucens larvae and spirulina on the contents of selected endogenous bioactive (anserine, creatine and carnosine) and flavour-related (inosine and inosine-5´-monophosphate, IMP) compounds in chicken breast meat was evaluated. The results showed that the spirulina-based diet lowered the levels of anserine, carnosine and creatine compared to the control diet (3.3 vs. 4.1 mg/g, 0.15 vs. 0.72 mg/g and 1.49 vs. 2.49 mg/g, respectively) while IMP levels tended to be higher in spirulina-fed samples. Compared to the control group, Hermetia illucens-fed samples showed a lower content of bioactive peptides (anserine: 3.6 vs. 4.1 mg/g; carnosine: 0.39 vs. 0.72 mg/g; creatine: 2.03 vs. 2.49 mg/g), albeit to a lesser extent than the spirulina treatment group

The Effect of Algae or Insect Supplementation as Alternative Protein Sources on the Volatile Profile of Chicken Meat

: The aim of this study was to investigate the differences in the volatile profile of meat from chickens fed with alternative protein diets (such as algae or insect) through two different trials. In Trial 1, broiler chicken at one day of age were randomly allocated to three experimental groups: a basal control diet (C) and two groups in which the soybean meal was replaced at 75% (in the starter phase) and 50% (in the grower phase) with partially defatted Hermetia illucens (HI) larvae or Arthrospira platensis (SP). In Trial 2, broiler chickens were housed and reared similar to Trial 1, with the exception that the experimental diets replaced soybean meal with either 100% partially defatted HI or 100% SP. In both trials, chickens were slaughtered at day 35. Per group, 10 chickens were submitted to volatile analysis by using solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) analysis. Results in both trials showed that levels of several lipid-derived compounds were found to be lower in chickens fed an HI diet, which could be linked to a possibly lower level of polyunsaturated fatty acid content in HI-fed chicken. In addition, the dietary treatments could be discriminated based on the volatile profile, i.e., the substitution of soy with HI or SP distinctively affected the levels of flavor compounds

The Effect of Algae or Insect Supplementation as Alternative Protein Sources on the Volatile Profile of Chicken Meat

The aim of this study was to investigate the differences in the volatile profile of meat from chickens fed with alternative protein diets (such as algae or insect) through two different trials. In Trial 1, broiler chicken at one day of age were randomly allocated to three experimental groups: a basal control diet (C) and two groups in which the soybean meal was replaced at 75% (in the starter phase) and 50% (in the grower phase) with partially defatted Hermetia illucens (HI) larvae or Arthrospira platensis (SP). In Trial 2, broiler chickens were housed and reared similar to Trial 1, with the exception that the experimental diets replaced soybean meal with either 100% partially defatted HI or 100% SP. In both trials, chickens were slaughtered at day 35. Per group, 10 chickens were submitted to volatile analysis by using solid-phase microextraction (HS-SPME) and gas chromatography&ndash;mass spectrometry (GC-MS) analysis. Results in both trials showed that levels of several lipid-derived compounds were found to be lower in chickens fed an HI diet, which could be linked to a possibly lower level of polyunsaturated fatty acid content in HI-fed chicken. In addition, the dietary treatments could be discriminated based on the volatile profile, i.e., the substitution of soy with HI or SP distinctively affected the levels of flavor compounds

Volatile Profile of Grilled Lamb as Affected by Castration and Age at Slaughter in Two Breeds

The aim of this study was to assess the effect of castration and slaughter age on the volatile profile of cooked meat from Scottish Blackface (SB) and Texel × Scottish Blackface (T × SB) lambs. M. longissimus thoracis et lumborum was sampled at slaughter and subjected to volatile analysis by SPME-GC-MS. Rams had higher relative proportions, expressed as relative abundance (RA), in lipid oxidation products while castrates had higher RA in pyrazines and benzenoid compounds. There was no consistent age effect on the RA of volatiles, although rams in November and January had a different volatile profile to castrates. There were higher proportions of free branched-chain fatty acids in muscle from SB compared to T × SB lambs. Overall, the results showed that production factors affected the volatile profile of cooked lamb meat which may explain differences in lamb flavor. Practical Application: Lamb meat has a characteristic flavor which, according to the evidence to date, may be influenced by farm production factors like gender or slaughter age. Our results showed variations in the proportions of some flavor compounds in cooked lamb between rams and castrated lambs while an increase in slaughter age did not have a consistent effect on proportions of compounds.Department of Agriculture, Food and the MarineTeagas