Effects of postgrazing sward height on individual and per-hectare milk production of supplemented high-producing dairy cows
Notice bibliographique
Résumé
Residual sward height management is a key factor influencing milk production and grazed forage utilization per cow and per hectare in pasture-based dairy systems. This study evaluated the effects of postgrazing sward height on forage growth rate and DMI, milk production, and BCS in supplemented, high-producing dairy cows. The study captured cumulative treatment effects on animal performance across nearly an entire lactation, as well as sward dynamics over most of the tall fescue growing season. Thirty-two multiparous Holstein cows were assigned to 2 treatments: the control treatment, with a postgrazing sward height of 5.0 to 7.0 cm (CT), and the high treatment, with a postgrazing sward height of 12.0 to 15.0 cm (HI). The study spanned 215 d of grazing on a Lolium arundinaceum sward in a randomized complete block design, with 4 blocks, each measuring 3.2 ha, and consisted of 2 paddocks, each measuring 1.6 ha. Cows had one grazing session between milkings and were supplemented with a mixed ration in the opposite session. Rotational grazing was employed, with new strips allocated once the postgrazing sward height for each treatment was achieved. A new grazing cycle was initiated when plants reached the 2.5 to 3.0-leaf phenological state. Any extra or unused areas within a grazing cycle were always recorded. The postgrazing sward heights were 7.7 and 14.4 cm for the CT and HI treatment, respectively. Forage growth rate tended to be 21% higher in the HI treatment (40 vs. 33 kg DM/ha per day), and cows stayed longer per strip (3.9 vs. 2.9 d) and had 2.5 times more grazing cycles (8.3 vs. 3.3). Total forage disappearance was similar between treatments. Cows in the HI treatment had greater individual grazed forage DMI (+2.0 kg/cow) and BCS throughout lactation compared with CT cows. The HI treatment also increased the individual milk production by 10% (31.5 vs. 34.5 kg milk/d) while reducing concentrate intake per unit of milk by 10%, resulting in a tendency for higher income over feed costs at cow level. However, although we observed a tendency for a higher forage growth rate, this approach required a larger grazing area (1.18 vs. 1.60 ha/4 cows), leading to a trend toward 21% lower milk output per hectare (23,598 vs. 18,528 kg milk/ha). In contrast, the CT treatment supported a higher stocking rate but resulted in lower grazed forage DMI, higher supplemental feed input per hectare and slower BCS recovery. These findings highlight the importance of aligning grazing strategies with system-specific goals. Farmers seeking to maximize land productivity may favor lower postgrazing sward heights, although these must be managed carefully to prevent adverse effects on animal health, reproduction, and long-term productivity due to slower BCS recovery during lactation and lower BCS at the onset of dry off. Conversely, systems aiming to reduce feed costs may benefit from a higher residual sward height, which enhances individual cow performance and BCS while decreasing reliance on supplemental feed.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».