Laboratory of Nuclear Techniques

Montevideo, Uruguay

Laboratory of Nuclear Techniques

Montevideo, Uruguay
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Meikle A.,Laboratory of Nuclear Techniques | Mattiauda D.A.,Agronomy Faculty | Chilibroste P.,Agronomy Faculty
Animal Feed Science and Technology | Year: 2013

The effect of different sward herbage allowances and a total mixed ration (TMR) management on milk production, body condition, first postpartum ovulation and endocrine/metabolic parameters were investigated. Primiparous Holstein dairy cows ( n=44) were randomly assigned to one of the following grazing treatments ( n=11 each): high (HA, 30. kg), medium (MA, 15. kg) and low (LA, 7.5. kg) estimated grass DM available/cow/d and a TMR group fed ad-lib from calving to 56 days after calving. Body condition score (BCS) was registered every 15 days from one month before to two months after calving. Non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), cholesterol, plasma protein, albumin, urea, insulin, insulin like growth factor-I (IGF-I) and leptin were determined in plasma every 15 days from 15 days before to 56 days after calving. Progesterone was determined 2 times per week after parturition to determine first ovulation. TMR group had higher milk production in the first 56 days in milk than the HA and MA groups (P<0.05) which did not differ, and were in turn greater than LA cows (P<0.01). Overall, the TMR and HA groups had a greater BCS, protein and albumin concentrations than the other groups, suggesting a better energy balance. While HA cows presented a better metabolic status (smaller BCS losses, lower plasma NEFA and greater urea concentrations) than MA cows during the early postpartum period (15-30 days postpartum, dpp, P<0.05), HA cows differed (greater plasma cholesterol, albumin and urea concentrations) from LA cows later on (45-60. dpp, P<0.05). Greater plasma insulin and IGF-I concentrations were found in the TMR group (P<0.05), which is consistent with the higher nutrient density offered to this group. The reinitiation of ovarian cyclicity was delayed in MA cows one month after calving when compared to TMR and HA cows (P<0.05), which is consistent with the greater NEFA and lower urea concentrations in this period. The lowest probability of first ovulation throughout the study was observed in LA cows (P<0.05), which was associated with their endocrine and metabolic profile. In conclusion, sward allowance affects metabolic signals which in turn are associated with a different productive and reproductive performance. © 2013 Elsevier B.V.

Sosa C.,Animal Production and Food Science | Carriquiry M.,Animal and Pastures Production | Chalar C.,Biochemistry | Crespi D.,Animal Reproduction | And 3 more authors.
Animal Reproduction Science | Year: 2010

The growth hormone (GH)-insulin-like growth factor (IGF) system is expressed in bovine uterus during the estrous cycle and early pregnancy and is acknowledged to play an important role in regulating the development of the embryo and uterus. The leptin receptor (LEPR) is also expressed in the bovine uterus although it is not known whether its expression varies during the estrous cycle. In this study, the expression of the IGF-I and -II, the type 1 IGF receptor (IGF-1R), GH receptor (GHR) and LEPR transcripts was determined on endometrial transcervical biopsies collected on days 0 (estrus), 5, 12 and 19 of the cow estrous cycle (n=8). The expression of mRNA was determined by RT real time PCR using ribosomal protein L19 as a housekeeping gene. It has been demonstrated for the first time that LEPR mRNA is expressed in the bovine uterus throughout the estrous cycle and that it presents a cycle-dependent variation, with higher levels observed during the luteal phase. The expression of IGF-I mRNA was greatest at estrus and day 5 (100%), and decreased on days 12 and 19 to 47% and 35% of the initial values. IGF-II mRNA increased on day 12 and decreased sharply thereafter (to one-third of day 12 values). Interestingly, IGF-1R showed the same pattern as IGF-II: increased 50% on day 12 compared to values at estrus and presented a sharp decrease on day 19. The expression of GHR transcript was greatest at estrus and on day 5 and progressively decreased thereafter. These results show that the GH-IGF system components are distinctively regulated during the estrous cycle suggesting that modulation of the IGF system may influence uterine activity during this period. The increase in the uterine sensitivity to IGFs during the late luteal phase - as demonstrated by the increased IGF-1R expression - concomitant with the increased IGF-II mRNA expression may reinforce the role of IGF-II during early pregnancy. Moreover, leptin is also likely to play roles during early embryo development. © 2010 Elsevier B.V.

Guggeri D.,Instituto Nacional Of Investigacion Agropecuaria | Meikle A.,Laboratory of Nuclear Techniques | Carriquiry M.,Animal and Pastures Production | Montossi F.,Instituto Nacional Of Investigacion Agropecuaria | And 2 more authors.
Livestock Science | Year: 2014

This study compared different management systems applied early in life on body development, endocrine parameters and age at puberty in beef heifers grazing Campos grassland, from 75 to 539±1.5 days of age. Calves were allocated to three treatments: (1) Early weaning (EW, n=15) at 75±1.5 days of age; (2) Traditional weaning (TW, n=14) at 158±1.5 days of age; (3) Traditional weaning plus creep feeding (TW+CF, n=17). Early weaned and TW+CF calves received a supplement that supplied 26±1.1% of crude protein and 11.7±0.04. MJ ME/kg DM from 75 to 158±1.5 days. Traditional weaned calves had a greater average daily weight gain (0.86±0.03. kg/day; ADWG) than EW calves (0.75±0.03. kg/day) from 75 to 158±1.5 days, associated with greater IGF-I concentrations at the time of TW (112.9±10.7 and 63.4±10.3. ng/mL respectively; P<0.05) that had no impact on age at puberty. Traditional weaning plus CF calves had a superior ADWG from 75 to 158±1.5 days (1.25±0.03. kg/day; P<0.05), greater concentrations of IGF-I at weaning (185.3±9.6. ng/mL), were heavier and taller (P<0.02) from weaning to 539±1.5 days, and puberty occurred earlier (472±8.0 days of age) than EW (526±7.2 days of age; P<0.05) and tended to occur earlier than TW calves (484±3.4 days of age; P=0.06). We conclude that age at weaning had a short-term impact on body growth and IGF-I concentrations, that had no effects on the age at puberty. However, CF induced a faster body development, which was related to an earlier attainment of puberty. © 2014 Elsevier B.V.

Chilibroste P.,Agronomy Faculty | Mattiauda D.A.,Agronomy Faculty | Bentancur O.,Agronomy Faculty | Soca P.,Agronomy Faculty | Meikle A.,Laboratory of Nuclear Techniques
Animal Feed Science and Technology | Year: 2012

Effects of daily herbage allowance (DHA) on milk production and composition, body condition score (BCS) and grazing behavior of primiparous Holstein cows during early lactation were investigated. Cows were blocked by body weight (BW), age and BCS, and randomly assigned within block to one of three grazing treatments (. n=. 11 cows each) being: high (HA, 30. kg DM/cow/d), medium (MA, 15. kg DM/cow/d) and low (LA, 7.5. kg DM/cow/d) DHA. Cows were grazed in 8 consecutive grazing paddocks (GP) of 7. d of occupation each. The experiment was a completely randomized block design and data were analyzed as repeated measurement in time. Milk production was higher in HA and MA groups than in LA (24.3 and 22.7 vs. 19.2. L, P<0.01 respectively). Milk response to extra DHA was 0.43. L of milk/kg DHA between LA and MA treatments, which dropped to 0.19. L of milk/kg between LA and HA treatments. Cows in the HA treatment had higher BCS than cows in MA and LA treatments (3.18 vs. 3.05 and 3.07; P<0.05). Cows on all treatments mobilized BCS during the first 3 weeks after calving but, while HA cows lost ~0.5 points of BCS, LA cows lost 1 point. The probability of a cow grazing at any time increased (P<0.01) as the experiment progressed, being 54.5, 61.3, 66.8 and 68.7. min/100. min for GP 3, 5, 7 and 8, respectively. Probability of grazing increased linearly for cows receiving HA (0.39. min/100. min/d) and MA (0.44. min/100. min/d) treatments at higher rate than cows receiving LA (0.22. min/100. min/d) treatment. A linear effect of days in milk (DIM) on bite rate as well as an interaction of DIM by treatment occurred. At DIM. =. 0, the mean value for bite rate was ~15. bites/min, and the slope relative to DIM was higher for HA and MA cows (0.54 and 0.69. bites/min/d, respectively) than for LA cows (0.29. bites/min/d). The result of the present experiment evidence the major role of DHA on milk production in primiparous dairy cows during early lactation, being more important at lower levels of DHA. The lack of response on milk production to higher levels of DHA might have been related to the low effective grazing time and bite rate exhibited by early lactation grazing primiparous cows. © 2012 Elsevier B.V..

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