Search

This study evaluated the carry-over effects of ewe body reserves during early pregnancy on peri-partum adipose tissue metabolism. Forty-nine multiparous ewes were divided in three categories according to their body condition score (BCS) at day 30 of pregnancy (BCS < 3, 2.5-2.75; BCS = 3; BCS > 3, 3.25-3.5). Live-weight (LW) and BCS gains from 1st to 4th month of pregnancy were greater in ewes with BCS < 3 and 3 than in >3 animals. In contrast, in the last month of pregnancy, there was BCS decrease in all groups, although LW continued increasing. There were no differences in LW or BCS across ewe categories during this period. Peripheral leptin levels throughout the three last weeks of pregnancy were greater in ewes with BCS > 3 than in the rest, but this difference did not persist after lambing. Plasma metabolites related to energy metabolism, milk yield and lamb growth were not affected by ewe BCS in early pregnancy. Long-chain saturated milk fatty acids (FA) (C16-C24) were greater in ewes with lowest BCS (<3 and 3). Ewes with greater BCS showed greater monounsaturated and lowest polyunsaturated milk FA content. Ewe post-mating body reserves affect both pre-partum leptinaemia and post-partum milk polyunsaturated fatty acids content, but it had little effect on lamb performance. [ABSTRACT FROM AUTHOR]

Abstract: This study determined whether the rumen fermentation and histology traits may reflect the feeding strategy in light lambs (22–24kg). Thirty-two single Rasa Aragonesa lambs were assigned to one of four treatments in a 2×2 factorial design. The factors were the inclusion of forage in the diet (alfalfa grazing vs. concentrate-fed indoors) and lactation length (weaning at 13kg vs. suckling until slaughter). A multivariate canonical analysis discriminated individuals among feeding strategies. The main function differentiated weaned concentrate-fed lambs from the rest according to dorsal sac papillae height, ventral sac muscular layer thickness and the proportion of rumen valerate. The second function differentiated suckling concentrate-fed lambs from the rest according to plasma urea levels. Lactation length played an important role on rumen histology and protein utilization, especially in concentrate-fed lambs. Alfalfa grazing light lambs had similar rumen morphometric measures and fermentation characteristics, regardless of milk access. [Copyright &y& Elsevier]

This experiment aimed at evaluating the effect of calf management and breed on the metabolic and luteal function of post-partum beef cows fed at maintenance. Fifty multiparous cows, 22 Parda de Montaña (PA) and 28 Pirenaica (PI), were assigned to either suckling once-daily for 30 min (RESTR) or ad libitum (ADLIB) from the day after calving. Blood samples were collected to analyse metabolites [non-esterified fatty acids (NEFA), β-hydroxybutyrate, total protein and urea)], insulin-like growth factor-I (IGF-I) and progesterone (P4) at different intervals. Cows from RESTR maintained their live-weight (LW) over the first 3 months post-partum, whereas ADLIB cows lost nearly 4% LW. Both genotypes showed similar LW gains during this period (p > 0.10). Calf daily gains were lower in RESTR than in ADLIB treatment (p < 0.05), but similar across breeds (p > 0.10). Milk and lactose production were lower in RESTR cows than in ADLIB (p < 0.05). Milk and protein yield were greater in PA than in PI breed (p < 0.05). Serum NEFA, total protein and urea were higher in PI cows suckling ADLIB than in the rest (p < 0.05). Cows from PI breed had greater NEFA values than PA ones on the first week post-partum (p < 0.001). Circulating IGF-I was not affected by suckling frequency, breed nor their interaction (p > 0.10). Suckling frequency, but not breed, affected the interval from calving to first ovulation (p < 0.001), being shorter in RESTR than in ADLIB cows. In conclusion, the ad libitum suckling practice improved cow milk yield and offspring gain compared to once-daily suckling for 30 min from the day after calving, at the expense of impairing the onset of cyclicity. The effect of calf management was confounded with breed on the studied blood biochemical constituents, but any of these metabolites influenced the role of endocrine IGF-I in these genotypes. [ABSTRACT FROM AUTHOR]

Abstract: Nursing restriction and parity might be stressful factors influencing the challenging post-partum period. This experiment aimed to evaluate the effects of nursing frequency (in multiparous dams) and parity on faecal glucocorticoid metabolites after calving in beef cows (n =64). Also, the role of these effects on productive, metabolic and reproductive functions was assessed. From the day after calving, forty-six Parda de Montaña cows were assigned at random to three nursing frequencies: once-daily nursing (1×30min at 0800h) (RESTR1), twice-daily nursing (2×30min at 0800 and 1530h) (RESTR2) and ad libitum nursing (ADLIBC). Eighteen heifers were maintained with free access to their calves as in the ADLIB cow''s group (ADLIBH). Data were analysed through analysis of variance and survival analysis. The faecal glucocorticoid metabolites during the first three days post-partum were not affected by either calf management or parity (P >0.10) but they were greater at 12h post-partum than in subsequent samplings (P <0.05). Cow average daily gain (ADG) was greater in RESTR1 than in RESTR2 and ADLIBC (P <0.05). However, milk yield and calf ADG were lower in RESTR1 than in the rest (P<0.05). These traits did not differ between parities (P >0.10). Serum triglycerides and urea were not affected by calf management or parity (P >0.10). Peripheral cholesterol and IGF-I did not differ among suckling systems (P >0.10), but their mean concentration was lower in ADLIBC than in ADLIBH (P <0.05). Serum NEFA was lower in RESTR1 than in RESTR2 and ADLIBC on weeks 7 and 9 of lactation (P <0.05). Both RESTR1 and RESTR2 treatments showed lower serum NEFA than ADLIBC on week 11 post-partum (P <0.05). Serum NEFA were greater in ADLIBC than in ADLIBH on week 1 and after week 7 of lactation (P <0.05). Serum β-hydroxybutyrate was lower in RESTR1 and RESTR2 than in ADLIBC (P <0.05). Calf management did not affect significantly the interval to first post-partum ovulation or oestrus (P >0.10) but ADLIBC had shorter post-partum intervals to first ovulation than ADLIBH (P <0.05). In conclusion, calf restriction and parity were factors that did not affect cow''s welfare after parturition. Twice-daily and ad libitum suckled cows showed a similar productive and metabolic behaviour which differ from their once-daily suckled counterparts. This response did not trigger remarkable differences in the reproductive parameters of cows. Ad libitum suckled cows had different metabolic traits compared to heifers, as well as a shorter duration of the post-partum anoestrus than ad libitum suckled first-calf dams. [Copyright &y& Elsevier]

Abstract: This experiment was designed to study the effects of avoiding calf contact and genotype on the metabolic, behavioural and reproductive traits of beef cows during lactation. Fifty-two multiparous cows, 25 Parda de Montaña (PA) and 27 Pirenaica (PI), fed at maintenance were assigned from the day after calving to twice-daily nursing (2× 30-min sessions at 0800 and 1600h) either with fence contact with their calves (partial contact, PC) or without visual, tactile and olfactory contact (non-contact, NC) between suckling periods. Blood samples were collected to analyse metabolites (triglycerides, cholesterol, non-esterified fatty acids (NEFA), β-hydroxybutyrate and urea) and progesterone at different intervals. Cow–calf behaviour was monitored on weeks 4, 9 and 15 of lactation. Cow activity at oestrus was recorded through collars. Cows from both treatments and breeds showed similar live-weight gains during the first three months post-partum (P >0.10). Milk yield and calf gains were not affected by treatment (P >0.10) but they were greater in PA than in PI (P <0.05). Plasma triglycerides and urea in the cows were not affected either by calf contact, breed or week post-partum (P >0.10). Plasma cholesterol increased from week 6 post-partum onwards in PA cows (P <0.05) while this rise was delayed to week 7 of lactation in PI breed (P <0.05). Plasma NEFA was greater in blood from PC–PA cows than in the rest of groups (P <0.05), and these metabolites were greater on week 1 and lower on week 11 than in rest of samplings (P <0.05). Plasma β-hydroxybutyrate was not affected by either calf contact or breed (P >0.10), but it was greatest on weeks 1–3 than in the rest of lactation (P <0.05). Cows with PC calves took less time to first contact after they entered the barn than their NC counterparts (P <0.05). Dams from both contact treatments nursed their offspring and remained in close proximity for similar time within suckling periods (P >0.10). PA cows devoted more time than PI ones to lick their young (P <0.001). There were no differences throughout lactation in any of the studied maternal behaviours (P >0.10). Calf contact and breed did not affect the interval to first post-partum ovulation or oestrus in these cows (P >0.10). Under twice-daily nursing conditions, the limitation of visual, tactile and olfactory contact with calves did not trigger different maternal or reproductive traits in these breeds but only a slightly higher mobilisation of body fat substrates in Parda de Montaña compared to Pirenaica. [Copyright &y& Elsevier]

Abstract: The physiological response to concentrate supplementation in low milk potential ewe breeds has been scarcely studied. The aim of this experiment was to evaluate the effects of concentrate inclusion on feed intake, blood metabolites and milk yield and milk fatty acids (FA) composition of ewes raising lambs under forage-based diets. During the last 10 weeks of pregnancy (pre-partum period) and the 6 weeks of lactation (post-partum period), ewes were fed forage hay ad libitum with or without concentrate (inclusion of 300g/day in pre-partum period and 750g/day in post-partum) in a 2×2 factorial arrangement. The inclusion of concentrate did not affect the forage intake in pre-partum period (P>0.05), whereas during the post-partum feed intake was similar between treatments during weeks 1 and 2 of lactation, but thereafter it was greater in ewes receiving concentrate supplementation (P<0.05). The replacement rate was steady during the pre-partum period and it was not affected by concentrate supplementation or the number of carried foetuses (average 9.1±2.0%, P>0.05). During lactation, ewes supplemented with concentrate showed a replacement rate between 16% and 31%, being greatest during the first 3 weeks of lactation than afterwards (P<0.05). Concentrate supplementation during pregnancy did not affect subsequent milk yield (P>0.05) but this practice increased milk yield during lactation (P<0.05). The main milk FA groups did not differ between treatments (P>0.05) except PUFA n-3 content (P<0.001), which was greater in purely forage-fed ewes than in their concentrate-supplemented counterparts especially during early lactation (P<0.05). Likewise, the inclusion of concentrate in the diet hardly affected the blood energy metabolites concentration (P>0.05), except plasma β-hydroxybutyrate during the pre-partum period, which was greater in purely forage-fed ewes (P<0.05). In conclusion, the inclusion of concentrate in forage-based diets fed to unselected sheep breeds hardly affected forage intake but increased milk yield. During the last third of pregnancy, concentrate supplementation (300g/day) improved blood ketone status, whereas concentrate supplement (750g/day) during the 6 weeks of lactation did not improve the ewe nutritional status. A mild decrease in milk polyunsaturated fatty acids n-3 was observed due to concentrate feeding. In this context, concentrate supplementation should only be recommended to improve the nutritional status before lambing but this practice failed to counteract lactation demands during the post-partum period. [Copyright &y& Elsevier]