Browsing by Author "López-Villalobos N"
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- Item18O isotopic labelling and soil water content fluctuations validate the hydraulic lift phenomena for C3 grass species in drought conditions(Elsevier B.V., 2024-02-29) Oliveira BA; López IF; Cranston LM; Kemp PD; Donaghy DJ; Dörner J; López-Villalobos N; García-Favre J; Ordóñez IP; Van Hale RHydraulic lift is a functional characteristic observed in some plant species, often associated with their ability to withstand drought conditions. It involves capturing water from deep soil layers and redistributing it to shallower soil layers through the plant's roots. Bromus valdivianus Phil., Dactylis glomerata L., and Lolium perenne L. may perform hydraulic lift at varying rates. Using both direct (isotopic labelling - δ18O) and indirect (soil water content sensors) techniques, the study assessed and validated the hydraulic lift under extreme drought conditions on the soil top layer (below permanent wilting point), maintaining the bottom layer at high (20–25% filed capacity [FC]) and low (80–85% FC) levels of soil water restriction. Above- and below-ground biomass growth and morpho-physiological responses were evaluated. All species displayed some degree of hydraulic lift, with significant differences observed in the isotopic analysis and soil water content (p > 0.05). This illustrates that water was redistributed from the deep to shallower soil layer and validates that the hydraulic lift phenomenon is occurring in these C3 grasses. Bromus valdivianus presented the highest δ18O values (25.05‰) and highest increases in soil water content (µ=0.00626 m3 m−3; five events). Bromus valdivianus had a dry matter ratio of approximately 4:1 (0–20cm:20–40 cm). In contrast, L. perenne and D. glomerata had approximately 6:1 and 5:1, respectively. This difference in root morphology may explain the higher rate of hydraulic lift observed in B. valdivianus relative to L. perenne and D. glomerata. This paper validates the occurrence and provides initial insights into the hydraulic lift process occurrence of temperature grass species.
- ItemLow Birthweight Beef Bulls Compared with Jersey Bulls Do Not Impact First Lactation and Rebreeding of First-Calving Dairy Heifers—A Case Study in New Zealand(MDPI (Basel, Switzerland), 2022-03) Coleman L; Martín N; Back P; Blair H; López-Villalobos N; Hickson R; Bittante G; Mantovani RDairy heifers in New Zealand are typically naturally mated by Jersey bulls to produce low-value non-replacement offspring sold for slaughter a few days after birth. Producing a beef-sired calf from a dairy heifer will increase the value of these calves for beef production but may compromise the subsequent career of the animals, in terms of milk production, rebreeding success, health, or survival of the heifer. This study aimed to determine the impact of low birthweight Angus and Hereford bulls versus breed-average Jersey bulls on the reproduction and production traits of first-calving dairy heifers. The experiment included 304 heifer-calf pairs over 2 years. Calves sired by Angus and Hereford bulls were 3.5–4.4 kg and 3.7–6.8 kg heavier than Jersey-sired calves and had a 4.2% and 9.3% incidence of assistance at birth for normally presented calves over the 2 years, respectively. No normally presented Jersey-sired calves were assisted. There was no difference in body condition score, pre-calving live weight, milk production, pregnancy rate, inter-calving interval, re-calving day, and 21-day re-calving rate of heifers mated to the different breeds of bulls. The results indicate that the Angus and Hereford bulls with low birthweight and high direct calving ease estimated breeding values (EBV) can be used to produce calves of greater value than Jersey-sired calves without impacting dairy heifer production. However, a small increase in assistance at calving could be expected.
- ItemPhenotypic correlations of milk urea and the efficiency of crude protein utilization with milk yield traits and cow performance in two contrasting dairy systems in New Zealand(NZSAP, 2018-06-13) Correa-Luna M; López-Villalobos N; Almeida Jr GA; Donaghy DJ; Kemp PDThe objectives of the present study were to investigate phenotypic correlations of milk urea (MU) and efficiency of crude protein utilization (ECPU) with milk production and cow parameters in two contrasting herds. Between July 2016 and May 2017, 210 cows were milked twice daily with high supplementary feed inclusion (HS) and 258 cows were milked once daily with low supplementary feed inclusion (LS). In early, mid and late lactation, milk samples were collected to measure MU. At every herdtest date, ECPU was calculated as protein yield (PY) divided by crude protein intake (CPI); this last variable derived from intake estimations of metabolizable energy requirements. Positive correlations between milk yield (MY) and both dry matter intake (DMI) and CPI were observed in LS and HS. The ECPU only correlated positively with MY traits in LS, and there was no correlation of CPI with MU in either herd. A moderate negative correlation of ECPU with live weight (LW) was observed in both herds, but it was stronger in LS. By suppressing MY due to the reduced milking frequency of cows fed LS, these cows gained LW, had higher body condition score and CPI, and lower PY, reducing the ECPU. No correlation between ECPU and MU was detected.
- ItemProductivity, profitability and nitrogen utilisation efficiency of two pasture-based milk production systems differing in the milking frequency and feeding level(2/02/2021) Correa-Luna M; Donaghy D; Kemp P; Shalloo L; Ruelle E; Hennessy D; López-Villalobos NThe aim of this study was to model the productivity, profitability and the nitrogen (N) utilisation efficiency (NUE) of two spring-calving pasture-based milk production systems differing in milking frequency and intensification levels in New Zealand. For this purpose, physical performance data from a low-intensity production system where cows were milked once per day (OAD-LI) and from a high-intensity production system where cows were milked twice per day (TAD-HI) were employed. OAD-LI cows were milked once-daily with a stocking rate (SR) of 2.1 cows/ha and fed diets with low supplementation (304 kg pasture silage/cow) with applications of 134 kg N fertiliser/ha and TAD-HI cows were milked twice-daily with a SR of 2.8 cows/ha and fed diets of higher supplementation (429 kg pasture silage and 1695 kg concentrate/cow) with applications of 87 kg N fertiliser/ha. The Moorepark Dairy System Model was used to evaluate production, economic performance and N balance on an annual basis. Despite the higher feed costs of TAD-HI as more supplementation was utilised, profitability per hectare was 16% higher because more cows were milked with a higher milk yield per cow (milking frequency) when compared to OAD-LI. At the cow level, the NUE was higher in TAD-HI (30% vs. 27%) reflecting the better balanced diet for energy and crude protein and higher milk yields as a result of milking frequency. At the farm scale the NUE was higher (38% vs. 26%) in the TAD-HI due to the losses associated with the imported feed being excluded and higher N captured in milk. These results suggest that milking frequency, the use of feed supplementation and application of N fertiliser as management tools on grazing dairy systems affect productivity, profitability and N balance. Further studies are required to find optimal stocking rates in combination with the use of supplementary feed and N fertiliser application that maximize milk production and profitability for OAD and TAD milking production systems but minimize N losses.
- ItemService Sire Effects on Body Condition Score, Milk Production, and Rebreeding of Mixed-Aged Dairy Cows Bred to Angus and Hereford Bulls—A Case Study in New Zealand(MDPI (Basel, Switzerland), 2021-12-01) Coleman L; Back P; Blair H; López-Villalobos N; Hickson R; Meyer UBeef-breed bulls are used in dairy herds to produce a calf of greater value for finishing than calves sired by dairy bulls. There is limited research about which beef-breed bulls are most appropriate, and whether any negative impact on cow performance in terms of milk production and rebreeding should be considered. The aim of this case study was to compare the body condition score, milk production, and rebreeding performance of mixed-aged dairy cows bred to a selection of Angus and Hereford beef-breed bulls. Body condition score, post-calving live weight, milk production, rebreeding performance, and survival of 952 mixed-aged dairy cows artificially bred to 65 Angus and Hereford bulls were compared. There was no effect of service sire on post-calving live weight, days in milk, milk production, or inter-calving intervals of mixed-aged cows. Service sire had an effect on the calving day due to differences in gestation length (p < 0.001), although this did not translate into an effect on days in milk. A longer gestation length negatively influenced pregnancy rates, and greater birth weight of the calf negatively influenced survival to rebreeding (p < 0.05), indicating the potential for an effect of service sire. Selection of beef-breed service sires for dairy cows should include emphasis on lighter calves and shorter gestation lengths. The general absence of the service sire effect on the parameters measured in this study indicated that any of the service sires used in this experiment would be appropriate for use over dairy cows.
- ItemSire Effects on Birth Weight, Gestation Length, and Pre-Weaning Growth of Beef-Cross-Dairy Calves: A Case Study in New Zealand(MDPI (Basel, Switzerland), 2021-09-01) Coleman L; Back P; Blair H; López-Villalobos N; Hickson R; Meyer UProduction of beef-cross-dairy calves from dairy cows increases the value of non-replacement calves born to the dairy herd. The use of beef-breed sires may impact on calf birth weight, gestation length and pre-weaning growth rate of calves, which in turn influences the profitability of the dairy farm. The aim of this case study was to compare the birth weight, gestation length, and pre-weaning growth of progeny born to mixed-aged dairy cows on a single farm which were artificially bred to a selection of Angus and Hereford bulls, typical of those used over dairy herds in New Zealand. The birth weight, gestation length and pre-weaning growth of 980 calves sired by 65 sires were compared. Mean progeny birth weight (range 33.3–41.4 kg), gestation length (range 276.1–288.6 days), age at weaning (range 70.3–88.3 days) and pre-weaning ADG (range 0.63–0.76 kg/d) differed among sires (p < 0.001). There was a negative genetic correlation (−0.31) and positive phenotypic correlation (0.36) between gestation length and birth weight. Age at weaning was negatively correlated with birth weight (genetic: −0.56, phenotypic: −0.57). Bulls used in this study, and other bulls with similar genetic merit for birth weight and gestation length would be suitable for mating mixed-aged dairy cows in New Zealand.
- ItemThe Season and Decade of Birth Affect Dairy Cow Longevity(MDPI (Basel, Switzerland), 2024-03-01) Bobadilla PE; López-Villalobos N; Sotelo F; Damián JP; Meyer UDairy cow longevity is associated with three key areas: animal welfare, the economy, and the environment. In pastoral dairy systems, cows are exposed to environmental hardships and variations in feed supply associated with the seasonal growth of pastures. The objectives of this study were to generate base parameters for longevity and evaluate the effect of season and decade of birth on herd life (HL) and length of productive life (LPL) for dairy cows in pasture-based production. Records from the Dairy Herd Improvement Database at the Instituto Nacional para el Control y Mejoramiento Lechero (Uruguay) were extracted. The dataset contained 313,146 cows born between 1 January 2000 and 31 December 2019, classified by decade and season of birth. HL and LPL were calculated for each cow. The effects of season of birth, decade of birth, and the interaction between them on HL and LPL were evaluated using a generalized mixed model. The mean HL was 73.4 and mean LPL was 42.0 months. Cows born in spring had longer LPL and HL (p < 0.001). Cows born in the 2010s had significantly shorter HL (12.8 months) and LPL (9.14 months) (p < 0.001). In conclusion, the season and decade of birth have an impact on the longevity of cows in pastoral-based systems. This study is the first to demonstrate the effect of season of birth on long-term longevity.
